Today I spent entirely working on the drivetrain for the motor, since that part has to be finished before the pedal drivetrain can be setup, both for clearance reasons, and because the pedal's freewheel/receiver-chainring will attach to the outside of the motor's receiver chainring.
I did get it working, as this video shows. The bike is upside down so I could run the wheel without touching the ground, and so I could see and adjust things better. I need to make a teststand or kickstand that will keep the rear wheel off the ground and hold the bike vertically straight.
There's an extra roller in this video I had to use for now, because the small 1/2" ScootNGo chain used for the motor's final reduction stage is ten links too long for this application, and I don't have a safe method to shorten it, since the bike-chain tool I have doesn't work on links this small. The roller is the serpentine-belt tensioner from the dead '85 Ford LTD, as it is metal and won't wear the way any of the other potential tensioners I could make would during these tests. It's also already on a sturdy right-angle bracket, which made it extremely easy to securely clamp to the white ex-fork used for the rear interframe support bracket. Tensioning just means loosening the two radiator-hose clamps (also from the LTD) and scooting it up the tube, then retightening the clamps. Same way I tension the belt for the motor, by sliding the motor along the bottom tubes of the Magna's rear triangle.
It's running on only 24volts, from two of the car batteries, with no controller (just direct power). The reason it's in the gear it's in is that I have no cables connected to the derailers yet, so the rear one is in the default highest gear, and the unadjusted front derailer falls on the middle chainring there (I think the bike that derailer came from originally only had two front chainrings, but I can't really remember). Since each front gear gives about the same change from each other as two rear gears do, then if I were to shift into the largest chainring on the front, it would be about like shifting two more gears up in back, if they existed.
Unfortunatley, the drivetrain broke not long after this, as I was testing the bike's rear brakes with the motor running (to see if they would stop it even if the motor was going, in case of emergency on the road if the motor controller fails to "full on"--unlikely but possible). I was so absorbed in thinking how to fix it and improve it that I forgot to take any further pics today. :-(
The part that broke was the threading for the orange chainring's spotwelded-on nut, which both holds it onto the former pedal-axle and transmits it's energy into that axle. The nut's threading stripped out, as it was too soft a metal. The threading on the axle was fine. I had only gone with the hex nut because I found that using the part I'd intended to before would end up with the chainring too far out of line with the driving chainring in front of it.
Since all the thin hex nuts I have for this reverse-threaded shaft are essentially identical, all coming from scrapped cheap kid's bikes and the like, I decided to change how I would do this. The part I was going to use before is the much harder bearing ring, which is threaded onto that shaft just inside of the hex nut on a normal bike with one-piece cranks. I didn't use it until now because it's about 3 times as thick as the hex nut, causing the chainline problem mentioned above. But it also has 3 times the number of threads on it, and is very much harder metal (since it has to stand up to bearings rolling across one of it's surfaces under the pressure of pedalling's downstrokes).
In order to use it, I would have to bore out the hole in the center of the chainring's mounting plate so that it would allow the core of the bearing ring to fit thru it, so I could then weld them together. The lathe comes to the rescue again, since I don't have an actual drill press. I chucked up the mounting plate in the lathe's head, then put my largest Unibit into a lathe-mountable drill chuck, in the tailstock of the lathe. A few minutes' work later, I had a hole large enough for the core of the bearing ring to tightly fit into.
I clamped the two parts together and welded them. When I was done, I found that something in the heating/clamping process had severely warped the plate, to the point I could *see* the curve in it. It was not curved at the center, where it was welded to the ring, only as it got towards the outer edges. Rather like an old vinyl record left in sunlight, but without the small wavy warps in it. The only fix I had was to hammer it as flat as possible, which unfortunately isn't very--perhaps at least 1/16" in either direction from a flat plane.
Now, it was already warped a little bit even when it was on the exercycle, to the point of causing part of the wobble you see in the orange chainring in the video above, but I didn't think it would get so bad that it could vary more than 1/8" in either direction from a flat plane, just from the welding/clamping process. It didn't change noticeably from the spotwelding of the hex nut, but it was not heated nearly as much for that, either.
Even with the warping, the chain doesn't come off, which is good. I will still need to replace the mounting plate with something much better for actual use, though, since I don't like the way it feels or sounds this way. Not only that, but when I get the excess links out of the chain, it will then be problematic, as it won't have the tensioner in it anymore, and the chain is likely to come off if a bump is hit while it's in the looser positions during the wobble.
The bad news is that the threads broke again--this time not on the nut, but on the shaft itself. The particular bearing ring I picked was chosen for it's apparent hardness being greater than that of any of the others (using the lathe's toolbit to try to scratch the non-bearing surfaces). It is apparently harder than the actual crankshaft it would have been mounted on, as when I stalled the system again by braking with the rear wheel rim brakes, it sheared thru the threads on the shaft.
This is a real problem, as I don't have any shafts that appear to be harder than this one, and I have no way to put threads on anything this size, much less of a metal hard enough to be useful.
I can weld the nut to the shaft for more testing, but I will need a repairable drivetrain with removable parts eventually, so I now have to think of another way to build this part which is sturdy and disassemblable. I already have a bunch of ideas from before I did this one, but don't have all the parts needed to build any of them (which is why I went with this version), so I'll have to think of a different idea using only the parts I do have.
One possibility is a rear hub, using the freewheel cassette as the front gearset (in place of the simple triple-ring it has now). This complicates things some in that I would have to weld dropout tabs onto the bottom bracket area of the Roadmaster frame, to give a place for the hub axle to bolt to. It also means boring out the holes in at least the larger two chainrings so they will fit on the freewheel, and bolting them to existing sprockets there. The very largest sprocket, which is on the inside anyway, would become the granny ring, as it is of the same or similar size.
Hopefully I can still use the standard front derailer, as long as the hub is mounted in-line with the seattube, and I can slide the derailer down far enough to still reach the chainrings correctly. If not, I'll need to either add another section of seattube somewhere for it, or I will have to try to adapt a rear derailer to do this job (I'm not sure it can, because of the very large difference in sizes between the three rings).
I'm still left with the problem of adding the leftside pedal-drivetrain freewheel, which should go on this section--I had a nice workable idea for the one-piece crankshaft setup, but that won't work at all for a hub-based one. I still have some other ideas left but they're not yet explored in any detail, and may be unworkable.
It is a little disappointing that such a major part failed so simple a test in this way, but I'd certainly rather have it all happen now than later on the road. I suppose this is one of the problems with essentially an improvise-as-you-go design. :-) It's still fun coming up with solutions, especially adapting things never meant for this into something very functional and useful.
One other issue I need to deal with is the motor's belt system. Despite using the lathe to do it, the plastic receiver pulley's inner hole is not perfectly centered. I'm not sure how I managed that, but I did, so I need to re-lathe it out a bit to make it perfectly centered, as it is causing a significant wobble in on the freewheel, which at high motor speeds shakes the whole bike a little bit, as if I was going over a roughly paved road. That also means the belt is being stretched and loosened a little bit each time it goes around, and will wear it out faster, and cause slippage, losing some motor power when that happens.
It may also cause other damage, such as bearing problems or even shaft problems in the motor itself, long-term. A similar issue with my friction drive, where the rear wheel was not exactly the same thickness all the way around, eventually helped cause the shaft failure of one of the two fan motors (documented in a previous post, if interested). I doubt the shaft will break on this treadmill motor, as it's much thicker, but it will wear the bearings faster than normal.
Gotta work tomorrow (and probably the next day), so probably no more blog entries for the next few days.
Friday, January 30, 2009
Today I spent entirely working on the drivetrain for the motor, since that part has to be finished before the pedal drivetrain can be setup, both for clearance reasons, and because the pedal's freewheel/receiver-chainring will attach to the outside of the motor's receiver chainring.
Today I didn't have much time to work on the bike, so all I really got done was trying out some various mockups of chainlines and whatnot for the pedal part of the drivetrain, and getting a final method for attaching the motor chainwheel without wasting a freewheel doing it.
This is the chainline I will probably end up with, using a derailer fixed in one position to tension the chain and hold it up out of the frame/etc.
I chose small chainrings for both ends of the pedal drivetrain mostly because it keeps the chain in a smaller line, making less objects for me to have to keep it out of the way of. I may yet change the chainrings, but right now the front will be 18T, and the rear 16T, not because I wanted them different, but because I don't have a 16T that fits right on the pedal axle, but I do have an 18T off a kid's bike. The 16T rear is because that's what the fixed-gear freewheel has built into it. I might be able to bolt on an 18T chainring to the freewheel, or figure out a mounting method for a 16T cassette chainring to the pedal axle, to make them 1:1 ratio again, but 1.25:1 is not far from that, and it gives me a bit more power in the low-end range of pedalling than the 1:1 would.
I might end up flipping the derailer vertically, and using a mounting point on the rear triangle of the Magna instead of where it currently is clamped to. This will let the tensioner actually do it's job automatically, instead of having to be manually set by the angle of the derailer.
If it can work automatically, then it means I can attach a lever arm to it to rotate a potentiometer, or a magnet for a hall sensor, etc, and use it to measure the tension on the chain as I pedal. That will then be able to control the throttle of the motor--if I'm having to pedal too hard, it'll give the motor more power, so I can stay in my comfortable range without hurting my knees or other joints. (I suspect just having the different seat and pedal position will help that anyway).
This is the freewheel/receiver chainring for the pedals. It's just hanging by the chain in front of where it will be mounted, as a mockup, but you get the idea. The freewheel allows the pedals to not be turned by the motor's input to the wheel, if it's faster than my pedalling. (If the throttle system works correctly, that shouldn't happen very often, except when I use the override throttle on the handlebars).
The orange chainring is the motor's receiver chainring, which is directly mounted to the power-transfer axle, so the motor turning that chainring will drive the rightside normal rear-end chainline/chainrings/wheel.
The adapter plate (silver) behind the orange chainring is off the exercycle, formerly to adapt *it's* huge chainring to the pedals. Unfortunately it's centerhole was too small to fit the shaft here, so initially I was not going to use it. But I finally just got out the big Unibit and drilled out the hole to one size larger. The four mounting holes for the chainring itself don't line up, though, so I had to drill out a new set of holes in the adapter plate just inside the circumference of the original holes. Now I just need to find thinner-headed bolts and nuts to use, without just grinding down the ones I have on it (which I'll do if I have to), so I can more easily fit the pedal receiver chainring's freewheel on here.
The black hex nut you see will not be needed later, because the adapter plate will be welded to a retainer/bearing nut from a similar one-piece crank set, so that threading the chainring on will tighten it as the motor runs, rather than loosen it or potentially spin it.
I will do the same thing for the pedal freewheel, but first I have to extend the threaded portion of the crank's shaft--this means welding a second crankshaft onto the end of the first, which is going to be difficult. I can't just bolt one on, because I have no way to make the counter-clockwise threads needed to keep it all from unscrewing itself as it is used. There's a few steps to that.
First, I took the cut crankshaft I already had and chucked it up in the lathe, machining away at the face of the shaft's end until it was perfectly flat and perpendicular to the shaft. That gives me a much better chance of getting the shafts lined up right. Next I will do the same thing to the shorter cut piece of a second one-piece shaft, which will only be the smaller threaded portion from the left side of the crankshaft. After they're both finished properly, they should mate to give a straight shaft. I'll then clamp them together end-to-end, and weld them together between the threaded sections. This weld will be critical to get right, as it will be taking the load from all the pedalling I do. It won't have to support the motor load, too, fortunately, which means that even if the pedal weld fails at some point, I could in theory limp home on motor only if I had to. I might (for testing stages) make up a second of these shafts, and keep it with me just in case. :)
Once that's done, I'll be able to thread on the pedal freewheel with it's retainer/bearing-nut, which again will just tighten with use rather than unscrew.
More soon, once I get all this drivetrain stuff finished--then I can put the chains on it, setup cabling and brakes and shifters, adjust them all, then try riding it. Then I'll know if it really sucks or if it's actually rideable.
Posted by M.E. at 1/30/2009 12:20:00 AM
Wednesday, January 28, 2009
I finally decided on the white fork as the rear-frame-connection brace, and did a little grinding on it's former headstock-end, so I could fit it more perfectly into the triangle formed by the Roadmaster seatstays and brake bridge.
Once it fit correctly I then bolted it to the Magna frame's dropout tabs, in the little open triangle above and forward of the actual dropout slots.
After verifying the frames were aligned and centered like this, I welded the Roadmaster end of things, and left it all assembled, where it shouldn't need to be taken apart again, hopefully. At least, not until I have to break it down for storage, etc. It's very stiff, and doesn't appear to flex at all in handling. The real test will be on the road, of course.
I have been needing to remove some of the fixed-gear freewheels from smaller bike wheels for a while, but didn't have (and can't currently afford) the correct tool to do this. Since one of the more common versions I find of these freewheels is a four-position recessed-square-hole drive, I decided to take one of the wrenches I have duplicates of, and turn it into one of these tools.
I welded two tall bumps at the correct spacing, then immediately quenched it in cold water, to harden the metal more than it would be if it cooled slowly. Then I ground and filed away at the bumps until they were close enough to square to fit in the freewheel drive slots, and correctly mate the side faces together tightly. I quenched it again after the high-speed angle-grinder was used (I don't know if that makes as much difference as the quenching after welding does).
To use it, I just fit it onto the freewheel with the axle bolt still on the hub, and cover it with a large thick washer. I put the axle bolt's retainer nut on and hand-tighten down until the whole thing is snug, so the wrench can't pop out of the drive holes. Then I use it the same way as a regular freewheel remover (like the one for my Shimano style multigear freewheels), and turn it counterclockwise with the wheel rim clamped down between two pieces of wood, or if it's really tough, tap it hard with a hammer to turn it. The one in the picture didn't hardly need any coaxing, and came off pretty easily. Another one took the hammer to get off.
Now that I know the method works, I'll be making another tool similar to it to remove the 2-slot freewheels, which are a different spacing from the 4-slot ones. I have one of those right now. I also have an old Suntour multigear hub I'd like to remove from it's hub (the wheel around it wasn't even there when it was given to me, just some twisted spokes!), but it has yet another type of 2-slot drive, requiring yet another tool to be made.
I needed to find a mounting method for the motor drivetrain's rearmost chainring, which is the 60T from the old electric scooter carcass, to the pedal-axle I'm using at the Roadmaster's BB. Since I don't have any convienently-sized adapter plates already made to take the freewheel-sized hole in the chainring and convert that to the pedal-axle size, other than some larger-than-this-chainring chainrings I'd have to cut down in size, or scrap metal I'd have to lathe and drill out, I decided to just use a freewheel.
I don't actually need a freewheel in this location, but it doesn't hurt anything to have it here (other than it's small rotational mass), and the teeth conveniently line up to match the 4 bolt holes in the chainring. I'd prefer to use the actual freewheel that it came from (which has a 4-hole mounting ring integrated into it), on the old ScootNGo, but I still cannot get it off the wheel, until I make the correct freewheel remover tool. Also, the freewheel I'm using happens to have it's 4 drive-slots match up with the hex nut on the pedal-axle bolt, to allow it to drive the axle, once it's clamped in place.
On the outside (left end) of the pedal-axle, I'll have the receiver chainring for the pedal drivetrain, which I do need a freewheel for. I'd prefer it be bolted in via hole drilled in the pedal-axle and tapped for threads--unfortunately the only threads I can make are clockwise, which means that by itself, it will come unscrewed as I pedal along. So I'll have to secure it some other way, most likely by welds across the inner edge of the freewheel to the pedal axle. This means I will be damaging the freewheel in a way that makes it unusable on a regular hub again, which I don't want to do, but seems unavoidable at the moment.
Since I won't be able to tighten it down any other way, I'll use a large washer on the outer (left) side of the motor drivetrain chainring, welding the washer to the pedal axle. I'll also be welding some extra grip surfaces (just like I did with my freewheel remover) on the pedal axle's hex retainer nut to fully engage all four of the removal-drive slots. If possible, I'll do this in a way that leaves it still removable from the axle, but if not, so be it.
Last post I mentioned using a standard socket wrench's drive socket to hold the small chainring for the motor drivetrain, onto the belt-to-chainring device. This is the socket and the chainring:
They'll slip over the axle something like this:
where I have a piece of hub core tube on the left end of the axle, then the socket and the chainring slipped into it. Farther down the right are some brass-bushing/plastic spacer bits from the exercycle the chainring originally came from, which should serve to keep the chainring away from the dropout tabs, and line it up with the rear (larger) chainring. I have not yet cut the hub itself that I currently have the device assembled onto, because I am still trying to find the hub I cut apart before. I'd rather destroy as few things as possible, so I can still use them for other projects (and regular bikes) when needed. Anything that doesn't require modification is better, for that reason and because it's less work. :-)
I decided on and finished a testable version of the remote steering, via push/pull rod. Since I don't have actual Rod End Bearings available other than whatever giant ones might be in the Ford, I used 1" diameter eyehooks (salvaged some years back from someone's scrapped porch swing in an alley, I think), with washers stacked inside the hole just a bit taller than the actual eyehook, to be able to shift around a little bit during pivot, as if it were a bearing.
To make the rod itself, I simply welded the nuts for the eyehooks to thick washers, then welded the washers on each end of a small steel tube, formerly part of the handle of someone's discarded weedeater. The nut is on the inside of the tube, so it will look neater later on, after I file off the ugly extra bits of my welding job.
Then I just threaded the eyehooks thru the nuts until I had about the right distance from each part of the steering setup--the remote handlebar stem and the actual front fork stem. Each eye was bolted to it's respective pivot point as described above, and verified that the whole thing pivots as it should.
It doesn't have a huge range of motion compared to regular direct steering, but it is better than the chain steering would have been, and is both easier to fix on the road if need be, and less likely to have to do so. I haven't measured the steering angles but they are equal both left and right, and appears to be sufficient to steer normally. I get more steering range with this than the old dead Honda gas scooter has even with it's direct steering, and I doubt I will need more than this. I'll find out during testing, once I have a drivetrain working (either motor or pedals).
Posted by M.E. at 1/28/2009 11:50:00 PM
Tuesday, January 27, 2009
Today was the first of four days off in a row; ideal time (and weather) for doing as much work as I can on this project, perhaps even getting it to a road-testable stage.
I finally figured a way to connect the two frames strongly, but I cannot do it with the parts I have available without welding a few things. :-( I had really hoped to be able to do so without that, but I'd have to either go buy things or I'd have to wait until I found them, and neither of those is a good alternative, since I already have everything I need to weld the parts together. It will still be able to disassemble relatively quickly into two halves, which was part of my no-weld goal, though the welding means it will be more difficult for someone else to replicate, if they don't have a welder handy (though I imagine if they could build this, they could come up with a DIY welder easily enough).
The first thing needed was to add a long seatpost fixed to the front edge of the headstock tube on the Roadmaster frame. To do that, a filler had to be added between the bearing cups so the frame is taking the load, not the cups--those cups are meant to take only a vertical load, and don't have enough inserted metal into the frame to actually hold together, and would probably just rip out of the ends of the tube with these loads over time. The best place to get a filler was some more bike frame tube, in a diameter just a shade larger than the existing headstock tube. Part of the front of the old wrecked Schwinn 24" that I used the rear triangle of for the Original Recumbent (OR) has elliptical tubing with the dimensions I needed, so I clamped it down and cut a short length from it, split down the center across the short axis.
This will fit on the headstock tube so that the new tube section has it's long axis protruding beyond the bearing cup circumference, so the seatpost can be welded to the new tubing without doing anything to the cups, and potentially causing problems later with steering.
After cutting out the section above, I verified it's fit and ground off the paint around the weld area:
Then just to be sure before welding, I set all the parts in place flat on the ground, to check that the frames would then sit where I needed them to, with the right spacing down between the various sprockets and belt pulleys, to prevent interference during a ride:
Then I tackwelded the tube half onto the headstock, then clamped the seatpost to the modified headstock's front edge, ensured alignment was as perfect as I could make it, and tackwelded the post on. I rechecked the fit, and it all lined up as intended the first time. I fully welded the parts together, then reassembled as below:
The idea is that this seatpost goes down at least as far into the seattube of the Magna frame as it is welded onto the headstock of the Roadmaster frame, and clamped into place by the seatpost clamp built into the Magna frame. I may add a second clamp between where the seatstays and the toptube connect to the seattube if I feel any issues during testing, but I don't think it will be needed.
Now, the steering was something I had been toying with various ideas for, and the chain-sprocket steering was what I wanted to do just to see how well it would work. But because of spacing and body-length issues, as well as strength of joins, etc, I didn't want to move the Roadmaster headstock back too far from the Magna seattube. That meant I wouldn't have room for a full-circumference sprocket on the bottom of the headstock, which is the only place it would easily line up with the top of the Magna headstock. This would severely limit my possible steering angle, by the amount of sprocket I could leave intact (the chain must remain fully on sprocket at all times or it will become detensioned and come off, leaving me with no steering!)
So I decided a rod-steering would be better, and looked around for various things to use for the rod. I have a number of things I can use, and one of the ones I decided against (but was nearly perfect in every way except being too soft a metal) is pictured above.
An aluminum stem from the old 70's Schwinn 10-speed I would have used for CrazyBike1.0's front frame will probably become the front steerer tie point, as it is at perfect right-angles where the clampscrew goes thru the bar clamp, and all I need do is add a bit of tubing around the screw itself for whatever steering rod I use to ride against, rather than the threads of the screw. Even a rollerskate bearing will work, if needed, as it's height and diameter are right for going between the open ends of the clamp.
Installing the stem at right-angles to the frame/wheel should give me enough torque to steer with. If not, installing it normally and clamping tubing into the frame that then has the steering-rod connection/bearing at it's farthest end will definitely give me whatever torque I need, depending on the length of tube I use (as short as possible to get the desired result).
Mounting at the handlebar end will probably be done via a clamp on the bars themselves, whichever clamp I find works best for the arrangement I end up with in the front, that won't interfere with the usual bar stuff (brakes, shifters, etc).
The last major structural decision is how to brace the rear portion of the Magna frame against sidesway and vertical movement vs. the Roadmaster's center portion. My original quick-made idea was to use a block of wood and clamps, but that will not last very long, as the wood crushes between the frames during use, and if the wood splintered it would probably cause the frame to come apart. Very bad on a ride, especially with the load on this frame from the motor and whatever batteries I end up with.
Below is the frame without any rear support, and just the seat-mockup to show about where it might go (actually farther forward and down, in front of the seattube), with a set of bars inserted on the steering headstock in the middle:
Next shows a black U-fork set into place approximately where it would be welded to the Roadmaster frame (at the center of the upside-down U, to the meeting of seattube and toptube), and bolted to the very rear of the Magna frame, just above the dropouts.
The version I will probably go with is this one, however, because this white fork is actually lighter than the black one by a few ounces, even though it is longer. I think it's probably better steel, too, given that it's just as hard for me to bend it (to spread the ends for meeting up with the Magna frame's triangle) as it is to do for the black frame, which is heavier and thus thicker metal to get the same strength.
This one will be mounted to a much more secure place on the Roadmaster frame--the unused caliper-brake bridge on the seatstays. It curves over the whole chainring area, which looks nice as well as being helpful in keeping me from contacting those (I can easily hang coroplast sheets from it to cover them, for instance). Again it will be bolted to the Magna frame just above the dropouts, and the triangle it forms from those two points to the Roadmaster's brake bridge should be sufficient stiffening to keep the chainlines from shifting (across the gap from Magna to Roadmaster frame).
Since there are two chainlines, that's pretty important. One is for the motor, and the other for pedals.
Another new thing is I am considering changing the device used to get beltpower converted to chainpower, so that it uses a very small chainring (14Tooth and 1/4" chain) instead of the 18Tooth 1/2" chain it currently would use, because it also means I can go from a 50Tooth chainring to an 80Tooth chainring with a slightly smaller diameter. That gives me a much better reduction of 5.7:1 instead of about 2.7:1, getting me closer to 90RPM (max) at the main input to the rear drivetrain to match my average pedal cadence. I'd need 7:1 at 36V or 4.7:1 at 24V to do it; this puts me somewhere between those, which I can deal with a lot better than 2.7:1 (which only really works at around 12V, which the motor does not get enough torque from to be useful, I expect, but haven't fully tested).
To do this, I will have to cut the hub used for the device in half (but not the axle), and use only the freewheel half. On the left side will be some nuts and spacer tubes, then in the middle will be the hexagonally-bodied 14T sprocket that came from the exercycle's "resistance wheel/fan". It conveniently already has a roller-bearing inside it that exactly fits the bike-rear-axle I'm using in this device (remember what I said about coincidences in a previous post?).
Since I don't want to weld to the sprocket or it's body directly (might need it intact for something else later), then I will slip over the 3/4" hexagon a 1/4" drive socket with a 3/4" hex head. The 1/4" drive hole means it fits perfectly over the axle, too, just outside of rubbing on it. That will be welded to the remaining half of the hub's center tube, to transfer the rotation of the freewheeled belt-pulley to the sprocket. (Years ago, I bought a barely-liftable giant bag of assorted sockets from Deseret Industries thrift store for a few dollars, so I have a *lot* of some sizes, certainly enough to use for things like this).
The bearing for the left side against the frame itself will be the cup and ring normally used inside the hub, but modified down to only the bare minimum, so the sprocket will end up in as perfect a chainline as I can achieve to the rear section. It's going to take some fiddling around to figure out exactly how to make it work, but I already have most of the idea in place, and will have the rest before I start cutting into the hub. What bothers me is that I already *have* a hub I cut in half around a year ago for one of the first motorization experiments, that came off the same white bike as the front fork to be used as the rear frame-join on this CrazyBike, but I can't find either half *anywhere* now.
Time to reorganize so all the bike parts are in sorted-out boxes of just one kind of part. :-)
Friday, January 23, 2009
First some full-bike pics of the frame with wheels (no seat or bars), with the motor and some sprockets/etc mounted, to give an idea of size. Front and back are both 24" wheels.
Pics are at twilight, so the camera did some funky stuff with the auto settings again, even though the flash was on for both pics.
I did a bit of digging and found a bent up rear wheel that I could pull the hub out of, to use for the belt-to-chain transfer freewheel device, in place of the orange one in the last post. Still using the same freewheel and axle and bearings, just changing the hub for a couple of reasons. First was because the orange hub still had the remnants of the JBWelded-on sprockets, which would take time and care to remove. Second was that the orang hub is a larger diameter core, whereas the hub out of the bent wheel is a very small diameter, not much bigger than the axle bolt itself. This saves a little weight, but mostly it gives me more clearance for anything that might have to go near the hub (between the frames).
I wanted to use the 14tooth sprocket from one of the cassettes, but neither that nor the 16tooth sprocket were large enough inside diameter to clear the spoke holes on the hub, which are what I need to use to clamp the sprocket down (using small screws and nuts salvaged from one of the ex-10BT racks that contributed to the most recent cargo pod/rack unit). So I had to use the 18tooth sprocket, which means I won't get as good a reduction ratio from that to the rear transfer sprocket, which is a 50-tooth at the moment (largest I can fit without problems hitting the 18 tooth sprocket itself).
The serpentine-style belt from the treadmill that I'm using for the first motor reduction stage is about 3.3:1, taking the ~2100RPM @36V and reducing it to ~636RPM. If I could get a 7:1 reduction to take that to ~90RPM, it'd be ideal. With 24V, I get about 1400RPM, reduced to 424RPM, which would only need about 4.7:1 reduction to get to 90RPM.
Because of noise and such, what I'd ideally like to do is use a belt from one to the other,
or failing that, a much smaller chain type, like that from the old electric scooter, or from a scrapped exercycle-type machine I got from Mark, but I don't have any low-tooth sprockets for that kind that will fit on the hub--the largest of the two I have is barely big enough to fit over the axle bolt, and the smaller (from the scooter motor) is too small even for that, perhaps a tad over 1/4" center hole diameter. That only leaves the two very large sprockets, one of which is over 6" in diameter and the other is around 9 or 10" in diameter. There's nowhere to put both of them, which I'd have to do--the smaller on the motor side, and the larger on the crank/wheel side. If I could somehow fit one of the smaller sprockets on the motor-side hub, then I could get about 7 or 8 to 1 ratio using the smaller of the two large sprockets on the wheel-side of things. That would actually be just about right with max output on a 36volt system to get about 90ish RPM at the crank/wheel end of the motor drivetrain, to match my approximate pedalling cadence. Then that would be processed thru the regular shifting drivetrain just like my pedalling is, to drive the rear wheel at whatever speeds.
I have no other belts that will work, or pulleys, with the right ratios, though I could get about 3:1 using the two serpentine-belt pulleys I took off the Ford a few days ago. I just don't have a belt I could use on those pulleys. I do have a number of V-belts, and some pulleys, but the pulleys are all about the same size, and so useless for any reduction work. I suppose I could lathe a very small one just for the hub end, but V-belts slip when wet, and this system is going to get wet.
So I am using regular bike sprockets, since I do have those in sizes that will fit the shafts I have to use, even though they're not the ideal ratios. It might work out better that way, since it means I will not run at full throttle to get equivalent motor power to my pedalling, so I will have that reserve of 1/3 to 1/2 of full power for emergency speed should it be required (I hope not!).
Anyhow, after reassembling that hub into the device, I mounted it in the Magna frame's dropouts as it will be used. Then I attached the treadmill motor as described in the last post, and adjusted the belt tension via sliding the motor forward and tightening all four radiator hose clamps (which came from the heater hose on the '85 Ford LTD). It holds very well, and does not move when I try to grab it and wiggle it around.
This is the motor and the device with receiver pulley and 18tooth sender sprocket, from right and left sides, with belt installed and tensioned. The frame is laying on it's side, with a spacer between the Magna frame and the Roadmaster frame to hold them about where they will need to be for clearance of the hub. Some later pictures I took show this is insufficient, and you'll see how little clearance there is for the rear-frame sprockets and chain.
More pics of the mounted motor and device, from the front/sides and rear/sides
These show the sprocket alignment between the motor's belt-to-sprocket device and the rear transfer sprocket.
Here you can see I had to increase the spacing betwen the two frames to ensure the very large rear sprockets clear everything on the device. I wish I could use smaller sprockets here, but the ratios I need preclude that on the left side (orange sprocket), and while I could probably use smaller sprockets on the right side (I won't need great speed from this bike, just a lot of pulling power), I don't actually have a smaller three-sprocket set that will work on the one-piece type crankshafts, which is what I used (with cranks cut off) for this.
The black set is the one that will share chain with the rear wheel cassette, actually taking the power transferred by all the previous stages and driving the wheel.
The orange one will take the motor power and transfer it to the black set. There will be another sprocket on the outer end of the shaft there, for receiving the pedal power and transferring it to the black set, but I have to first chuck up the crankshaft in the lathe and drill a hole down the center to tap thread into, to be able to bolt it on. I might end up doing a tackweld on both chainrings on that side, to keep them from loosening with use, as there is no retaining pin to prevent that (unlike on the right side), and the shaft is round unlike removable-crank shafts , so nothing to grab to. I might be able to just flatten or square the shaft instead, and bolt a squared-hole plate to each sprocket, but given the low surface area of the edge against that flat I'm not sure how durable that would be.
Now, it's been a while since I last had a video for you, so here are three!
The first is of the 24 volt power test, using two of the three car batteries:
There's no narration, because I forgot to say anything on any of the videos. ;) They all sound a lot louder than they really are, because the camera has a non-disableable automatic level control that loudens up all quiet sounds and quiets all loud sounds, and there weren't any really loud sounds so the camera basically turned up the volume on everything. Pardon all the neighborhood sounds. You can hear the fan noise, and compare it to the 3rd video at 36 volts, where it changes pitch as well as volume level, to something that sounds more like a familiar sound from under the car hood. :-) But considering that you can clearly hear bird sounds from a distance away mixed in with the motor sounds, the motor isn't really all that loud.
I have some ideas for quieting it down, though. I think some of the mechanical noise is vibration from a problem in the freewheel itself, and I will need to check the other freewheels I have to see if they do it too, or if it's just this one being damaged or worn causing it. When I enclose the fan blades in a guard, I will probably line it with something that should help absorb noise, like the liner under the carpet in the Ford. I'm not aiming for silent, but I do want it to be quieter than my previous setup, which was not very (surprising given that it was rubber rollers directly transferring to the wheel, but then again the motors were very noisy on their own, unlike this one).
This is a torque test for the 24 volt speed. I just took a 2x2 soft pine board and slowly fed it into the 18 tooth chainwheel, from a direction that wouldn't kick it back at me.
The idea was to see how much drag I could put on it like this before the motor stalled. Well, I couldn't stall it at all--it just chewed thru the wood, even if I crammed it between the sprocket and the frame. Slowed it down a lot, as you see, but never stopped. Current draw spiked from about 2 amps unloaded to 6 amps, on up to a bit over 8 amps when I had it between the sprocket and frame. :-) Since it's a 21-amp-capable motor, I don't think I have to worry about overloading it just yet.
The good news is that if it will put out this much torque at 24V, I may not even need the 36V setup at all, which is good because it means I can get away with less batteries. It might even work for just me (no cargo) on the flats with just 12V. I have not done a 12V torque test yet, but I expect I could probably stall it on that, at only 1/10 of it's rated operating voltage.
If it works at 12V, then I can actually run it off of one car battery for what would likely be quite a distance. Or I could parallel the SLAs I have and get more range out of them, but I still don't think they'll last more than a few minutes, at best, and probably not even that, due to their age.
This is a 36 volt test, no load, no torque test. If it doesn't stop at 24 volts, it isn't going to at 36!
As expected, it was noisier, but not intolerably so. I am almost afraid to see how it works at higher voltages, even given that it was designed to run at 120VDC, for 7000RPM total, including the belt and pulleys I'm using on it (which came from the treadmill with it).
Thursday, January 22, 2009
About two weeks before all the bike ideas in the last two posts started coming into my head, I had another flash of inspiration regarding the motor system, with the treadmill motor and belt drive, to get a freewheel between the belt and the rearwheel chain, so that pedalling without motor power would not force me to be pedalling against the motor's friction, but still allow the motor to drive the wheel even if I am pedalling, with no intervention on my part.
I checked the inside of the plastic belt-drive pulley the treadmill had used on the end of one of the treadmill main belt rollers, and found that it was almost exactly the same diameter as the Shimano freewheels I have several of, and also a bit narrower in width. Below are two freewheels still on their hubs, one Suntour 6-sprocket to the left, and one Shimano 6-sprocket to the right. Between them is the pulley, and behind them is the treadmill motor. In front of each are the sprockets and spacers that came off of them.
The orange hub still has some other sprockets (off an old Murray) JBWelded on from one of the first failed experiments at motorizing the Columbia with the old scooter motor. They'll have to be removed, as they aren't going to hold up for long with any serious load on them--they'll just shear right off the hub.
I will likely use several of the sprockets here for various things on the CrazyBike, potentially including steering-by-chain (one each of the same tooth-count on steerer and fork tubes), and one each of whatever tooth count is necessary for the receiver sprockets on the transfer axle of the rear frame's last drivetrain segment. Probably I'll use the sprockets that have holes already in them, as that makes it fairly simple to bolt them onto whatever I need to use them for.
If I get bored, I can also take out bike-stealing pirates with them, as ninja sprocket throwing stars. :-P
I considered both of the freewheels before choosing the Shimano, which I picked pretty much solely because it would take very little material removal from the pulley to make it fit, whereas it would have required removing almost all of the inner ring of the pulley to get it on the Suntour freewheel, due to the raised ridges it uses to engage the sprockets' tabs (the Shimano simply uses indentations on the freewheel, and tabs on the sprockets).
I lathed out about a millimeter from the inside of the pulley, and now it friction-fits perfectly (and tightly) onto one of the freewheels, with all the sprockets removed. Since it's a typical older freewheel, it has the last two small sprockets threaded on, so I used the smallest outer one of those to tighten against the outer face of the pulley, making it even more secure. I don't think I'm going to need to glue or bolt the pulley to the freewheel. It might be necessary eventually to install some bolts thru the pulley, across the lip of the sprocket's chain teeth and the lip of the back of the freewheel, but I may not need to, depending on the torque it will take as it is.
The way this works is the same way the rear wheel would normally work: as the pulley on the freewheel turns clockwise from motor power it will rotate the hub on it's axle, which will also rotate the sprocket that will be bolted to the left end of the hub, which will drive the rear chainsets that go to the wheel. But if the sprocket is rotated clockwise by the chain moving from pedalling, and the motor isn't running, the pulley will freewheel and not add the motor to the pedalling load. This means regen braking isn't possible, nor would recharging the battery by pedalling, but neither of those things would net me enough power to be worth *having* to do it all the time. Thus, the freewheel.
If the possibility of pulley slippage becomes reality, and I can't fix it by tightening the threaded sprocket, I might go ahead and notch out the inside surface of the pulley to match the Suntour freewheel's ridges, because that would definitely prevent any slippage. However, it may also weaken the pulley structurally to a point it could crack apart under load.
While I was at the lathe, I also cut the cast-iron pulley/flywheel assembly so that only the small-diameter pulley is left, leaving the flywheel portion off (if I want to smooth the acceleration, I'll do that via the throttle, rather than waste power driving the flywheel, especially given that it weighs as much as the whole motor!).
Since the flywheel that had slight vanes built into it was no longer there to do any air cooling of the open-cage motor. The label states that external cooling is required, at least for operation near it's specifications--I won't even be using it at 1/3 of that rating, but it will still get hot. I proved that by doing a rundown test on the new battery I had gotten last week (on the trip with the trailer and the canal and the rescue...)--hooking all three car batteries in series for 36V (38.5 under the motor's load, actually) and running the motor with no load other than it's metal pulley attached let the motor get pretty warm in the ~70°F weather, after about two and a half hours of running. Not too hot to touch or even uncomfortable to hold, but pretty warm. I did not measure the case temperature, but would guess at over 100°F. I'm sure it was hotter inside, at the coils and shaft. Since the motor was only drawing about 800mA at this mechanical load, that's not bad.
So I looked around for a fan solution that would be simple to set up, and a quick trip to the dead '85 Ford LTD in the driveway netted me the alternator fan (and a couple of the smaller and lighter serpentine belt pulleys), which has a hole for a shaft exactly the same size as my motor shaft. Odd, but I suppose a majority of this project is built upon the coincidences of fit of the parts I find. A couple of washers to keep the fan from touching the front housing of the motor, which press against the inner ring of the shaft bearing, and thus spin with the shaft and not rub on the motor itself anywhere, along with a hard rubber ring (originally intended as a garden hose gasket) placed between the fan and the back of the pulley, and then simply screwing the pulley down tight (it threads on counterclockwise, so the clockwise rotation of the motor holds it on, just like freewheels and such on bike hubs) holds the fan tight enough to spin with the shaft, no slippage I can see.
Now, this is a *metal* fan, and will be going about 2000+ RPM at 36V full throttle, so it's going to be kind of nasty if anything catches in it. I'll need to make a shroud to go around it to protect anything from hitting it, especially given where it will be mounted on the CrazyBike v2.0, under the frame nearish the ground. One of the reasons I did not try to find a way to actually fix the fan to the shaft, and instead used washers and the rubber ring, is that I would like it to not yank the motor to a grinding halt if it does somehow catch in something--instead it will just spin on the shaft, inducing some friction, but not stopping it entirely.
The motor was still almost as warm as when I'd stopped it to put the fan on, so I ran it again, and in about 5 minutes when I checked it it was very cool to the touch--no different than any other piece of metal laying about. That fan definitely does it's job, and while it is a bit noisy, it is not that bad, considering how well it works. It does add a significant mechanical load to the motor, almost doubling it's current draw to ~1.5A. Since the motor is capable of handling 21A at it's rated 120VDC, that's still not a problem, but it does mean I'm using significant power just to cool the motor. If I think of a simpler foolproof (and weatherproof!) solution that uses significantly less power, I'll change it out, but till then it's the best I've got.
Here's a temporary photo-mockup of part of the drivetrain using this setup:
The motor is slung underneath the frame on this bike (would be within the triangle if there was room, but the belt I have is not long enough, and I don't want to buy a new one till I have to, as this one is perfectly good, just very short). The belt tension is adjusted via moving the motor forwards or backwards along the chainstay tubes--most likely I will first use radiator hose clamps thru slits cut in the base plate of the motor mount to clamp the motor to the tubes, though a better clamping solution is on the drawing board. The pulley/freewheel/sprocket device is mounted in the former rear-wheel dropouts of the front frame. The belt from the motor drives the pulley which drives the chain, and chain tension is adjusted via the axle's position in the dropouts.
I'll have to wait and see how well this performs once I get the mechanics built enough to do a test. I can use the dying SLAs for short tests on the road, and in-house stand tests can be done with the car batteries, probably for hours. (I ran the motor without load other than fan and pulley for more than half a day without making much of a dent in the battery voltage, drawing ~1.5A the entire time).
The hardtail version I more or less came up with by accident, simply by seeing these two frames near each other when I spread all my frames out on the ground to ponder about. Again, it's just friction fit (and zip-tied) together, as a photo-mockup, to work out ideas with:
A 20" frame in front, the Magna, has the cranks down below as usual but much higher off the ground, because I have a 24" front fork in the headstock with 24" wheel. It doesn't really change the angle the fork would be at because the rear is also about the same amount higher off the ground, clamped to the down tube of the 24" Roadmaster frame.
The headstock of the Roadmaster fits over the seatpost/seattube of the Magna, in this position, and exactly aligns with it angle-wise. Because of this, it also aligns with the headstock of the Magna. That means that if I properly connect the frames so the headstock of the Roadmaster is kept empty and clears the Magna's seattube, I can use a piece of front fork steering tube inside it (already have one cut for the original recumbent [OR]) to mount the handlebars right in front of me, and not have to use absurdly-long rearward-facing ones as on the V1.0. These 'bars would hook up to a steering rod that ties to a stem mounted sideways on the front fork, and do my steering "remotely".
Since the angles of both tubes are the same, and line up from the bottom of one to the top of the other, I could also use the sprocket-and-chain method I wanted to use on the OR, but ended up not being able to due to the angle differences between my fork and my under-seat-steering tube. This would probably be even simpler to make from scrap than the tie-rod, but would probably be heavier (due to the chain).
As there are no worries about swivel and chainlength changing with the hardtail, I can more easily do the motorization, and I can incorporate many of the ideas for this I would have used for the OR, including using one drivetrain at the rear wheel for both motor and pedals, enabling me to shift gears for both, making them more efficient.
The way this drivetrain works is the cranks (on the bottom bracket of the Magna frame) have a single chainring on the LEFT side instead of the right, driving a chain that goes back to the bottom bracket of the Roadmaster frame, which will have two small chainrings from a rear cassette mounted to a shaft thru the bottom bracket shell. That shaft I've not yet decided what to make from, but most probably will be a one-piece crankshaft with the cranks cut off. The right side of that shaft will have the standard pair or trio of chainrings on it, with shifter, which will have it's chain going to the rear wheel.
The motor's belt goes thru a device explained in the next post that freewheels the belt pulley during pedalling-only modes, but otherwise passes motor power thru to a chainring, then via chain to the second of the two chainrings on that shaft described above. Thus both pedal and motor power go thru both the shiftable sets of chainrings, giving me the same range of gears for both, and the whole machine more efficient.
The motor itself hangs from the bottom of the Magna frame's rear triangle. The belt/chainring freewheel is bolted into the rear dropouts of this frame. The batteries, if I had the ones I want, would easily fit in some of the space of that rear triangle, with room for a toolkit bag, etc.
Unfortunately, since I still don't have anything of high capacity that is also even remotely small except my old nearly-useless SLAs, I may have to temporarily resort to using a pair of car batteries. :-( These could bolt in place of the cargo pods on the frame between the rear wheel and my legs, on either side of the motor system. They are VERY heavy, however, so I do not know if I can manufacture a casing that will hold them to the bike frame without damaging it--I seriously doubt either of these frames was designed to carry anywhere near that kind of load. A very small trailer just for the batteries might be necessary, but given the length of this bike is already almost a wheel longer than my Columbia, I'd really like to avoid that. If I did have to have a trailer anyway, it would allow me to expand the pair of batteries to a trio, and increase the power/speed available.
Still, even if I don't have batteries to properly run it from yet, I'm going to design this particular bike with the motor as part of it, and simply not bolt the motor on until I have a battery solution.
As long as I don't have to use the car batteries, I can also use longer cargo pods on this bike, as with CrazyBike V1.0.
The seat won't be the actual seat you see in the images, but one more like a narrow chair seat with back. There's a metal plate zip tied to the back of the seat in the images, just to show how it might appear. I'll probably make it out of wood, as that's easier to work with than any of the metal stuff I have without welding anything. If I had a pipe bender, I'd use a curved-pipe frame for the seat instead.
I'll have springs under the seat, made from a couple of saddle spring sets, because my shock-absorbing seat post is too large diameter to fit into the seattube of the Roadmaster frame. It should all mount normally to the seat tube via a standard seatpost.
Since I'm looking for the right scrap items to build the several subsystems (especially steering) I need to make my first recumbent bike idea actually rideable, I thought of another way to make a semi-recumbent without even welding anything. I'm still working on the concept to see if it can be done with only existing bike parts, without modifying any of them beyond what commonly available tools would do, just to see if I can actually do it.
So far, the most daunting part is the seat mount, and trying to decide if I want to make a hardtail or use a shock-absorbing rear wheel holder of some type. Hardtail is much simpler, but nowhere near as comfy to ride on our potholed streets. :) At the moment, I have a base idea for each type.
This is one idea for the shock-absorbing version, temporarily bolted and friction-fit together, to see what it looks like:
The idea is that the orange frame is hinged to the gray one at the bottom where they meet, and the seatpost you see at an angle from the front of the orange frame to the middle of the gray one is a shock-absorbing seatpost, spring-loaded inside, which would help absorb small bumps the rear wheel hits on the ride.
The hinging is done via the first method I'd used on the original recumbent idea (in this case bolting the crankshaft to the gray frame's rear dropouts), before I came up with the U-bracket mount. I'm not using the U-bracket idea simply because I wouldn't be putting the big motor and drivetrain on this version, just pedal power and cargo pods. The U-bracket also requires a hard plate to bolt the U-bolts onto, that rests against the bottom bracket shell of the orange rear triangle, and I would have to fabricate something (probably requiring welding) to bolt onto the gray frame without welding to it. Perhaps later I would install a version of the fan-motor friction-drive I had on the Columbia in the summer/fall.
Unfortunately that particular spring is not resistive enough, and fully compresses when I just lean on the bike, so I'll have to find a much harder spring-loaded tube. I've got to look up the shock loading for the old '85 Ford LTD in my driveway, and see if one of those is too hard for this use (probably is). If so, I'll have to keep looking. Perhaps a series of seat-bottom springs inside a metal tube, compressed by a smaller-diameter tube? Dunno, it's going to take some experimenting, which is the fun part. :)
The pedals will still go in the usual place in the middle of the gray frame, they're just removed in the pic because I have the bearings and axle for them soaking in oil to remove any rust, since the bike had been tossed out by someone because it is an old 1970s Schwinn bike, but it was one of the pretty good ones, with a very light brazed-together frame and all aluminum Suntour accessories, etc. Almost all I'm using from it is the frame itself, and the front derailer, and the pedal-axle/bearings.
A possible option is to use a bottom bracket plus a bit of seatpost and rear triangle, just enough to clamp securely to the top tube of the gray frame about halfway between seattube and headstock tube, and put the pedals up there, to get an even more reclined position. That increases the chainline length even more, and to ensure no chain-jumping might be better to run a chain on the left to the bottom bracket of the gray frame, thru it to the right side, then back to the rear wheel. That would also allow me to keep the shifting equipment in it's usual place, and have only a single small-diameter chainring on the actual cranks, with the shiftable pair or trio of chainrings on the main bottom bracket as usual, just with no cranks on them. This is much more engineering work to do, though, so wouldn't be done unless necessary.
The seat is going to make it a very different bike from what you're used to seeing, though--the seat will be a narrow but normal chair-type seat, leaned back a bit (at least 30°) down in between the two frames, in that "V". Just high enough and far enough back that at full extension my legs just reach the far end of the pedal stroke--this will make my riding position more aerodynamic than the upright position, but not be quite as laid back as a full recumbent, and not as low to the ground, either. The seat would be mounted to the gray frame, so it gets the benefits of whatever shock absorption system I can come up with.
The chain has to be about twice as long, and so with the shock absorbing movable rear frame also needs a tensioner on top as well as the normal bottom one, but it's still a shorter chain by far than my other recumbent would have been.
Steering for the simple version is just long-stemmed handlebars that go quite far back from the normal front steering stem, but that's not all that desirable, because it means my arms have to move in a much larger arc (farther sideways) than with normal handlebars right over the stem.
So I have an idea that puts a non-load-bearing steering stem down the seattube of the gray frame, right in front of where the seat will be, and so much more like the usual bike steering in feel. That stem goes down to just above where the front derailer clamps on, then a slit is cut in the side of the gray frame for a bolt to go into a pre-tapped hole in the end of the stem inside the tube, and that bolt also goes thru a rod outside the frame to a connecting swivel point on the front fork, above the wheel but below the frame, so that turning this new set of more-rearward-handlebars steers the front wheel. It's enough more complicated that I'm not doing it unless the other way is really uncomfortable or unworkable for some reason, but I expect it to turn out that way, so I'm preparing the idea just in case. :)
Since I am having trouble finding a spring that will have enough resistance to do shock absorption but not be *too* stiff, I thought of one more way to do it--hang the rear triangle upside down, so the swivel point is on top, and the spring is *stretched* from the bottom rather than compressed at the top, but this adds a number of complications and may be heavier. I do however already have a handful of springs that could work for this kind of thing, including some old hood springs. It's not likely I'll build it, but it is a possible alternative to think about.
Another possible method involves a pulley and cable from the top of a washing machine's tub (the part that keeps it in balance as it spins) and a spring (stretched again, rather than compressed) suspended from a piece of front frame sticking out behind the top of the rear frame. This one I really am not sure about, but it popped into my head while riding (as did most of the other variations), and I managed to remember it long enough to write it down.
All of these versions, due to their extra rear length, have more space for cargo pod up in front of the rear axle, which means I have to worry less about overhanging the axle point and tipping the bike backwards with heavier loads while going uphill or on certain kinds of turn. Also, if using the shock-absorbing rear wheel systems, if the cargo pods are all mounted on the main frame, any cargo in them won't get rattled around as much as it does now on my hardtail Columbia.
Saturday, January 17, 2009
I had thought the Tuesday of the previous blog post was bad, but today was much worse: I had to fish my trailer out of the canal. :( In the dark. :(
That was due in small part to my untested new hitch design, and not having a lock-nut on the bolt that held the pitch-swivel joint together. Easily fixed, and I even happened to have the parts necessary *with me* on the road, by chance. But I didn't notice the single nut holding the bolt in place was working loose, as I had many things on my mind from other prior adventures during the trip, and didn't think to check it on the return trip (loaded with stuff), though I *had* checked it on the outbound trip (empty trailer).
But the larger part of the problem was due to a jerk that PUSHED MY TRAILER INTO THE CANAL after it came off while I was riding on the gravel canal bike path. I'm not sure if it was just one or two of them, as it was already completely dark, with only my helmet light to see by.
The path alongside the canal in the area goes up and down a bit, so there are some decent grades for short lengths of path. I had just come up a "hill" and started to go down when it came off, but because I was going down I didn't really notice, and thought it was the mass in the trailer pushing me downhill, rather than a lack of mass OF the trailer keeping me from pedalling faster (it felt the same as it had on earlier hills). Only when I started up the next hill and didn't feel any drag did I realize something was wrong and looked back to see...nothing. :(
I immediately turned around and rode back, but the couple of people I'd passed after unknowingly losing the trailer had already passed where the trailer had gone missing, and were laughing really loudly, and sounded like they were running. I couldn't see them except vaguely, even with my headlight and helmet light, and nothing else was on the path at all, but then I saw my trailer floating in the canal.
I'm not sure if you can imagine how I felt at that moment--relief that it was floating, horror that it was in the canal, fear that I was going to be there in the dark all alone trying to fish it out, probably unsuccessfully, anger that someone would be so mean as to push it in to the canal, and a whole range of other things, all in just that moment.
I know the trailer did not go off into the canal on it's own, because in looking for a way down to the water, I quickly found the spot in the gravel where it had nosedived into the gravel and stopped, with the shape of the front of the trailer dug into a small pit of gravel right in the center of the very wide path where I'd been riding, obliterating my tire tracks, then sideways drag marks from there to the canal edge, which is a steep dropoff one cannot just walk down to water's edge from. At this area, it was somewhere around 4 vertical feet from water level to path level, on average.
The miracle was that it was floating, and that was ONLY because I had as usual strapped a big styrofoam cooler to it to hold the main cargo (the car battery), and any small loose stuff I couldn't just strap down to it. If it were not for that, I would never have seen it again, as even with just the trailer's weight, it would have sunk quickly, and with the large car battery I'd picked up (the whole purpose of the trip) it'd've just gone straight down. The cooler, being strapped down, had held most of the air inside it, too, which helped even more. The battery inside the cooler helped keep the whole thing not only upright, but with the back end hanging a bit lower in the water, which eventually helped me get it back up onto the path.
Now here I have to acknowledge that not all people are evil, unthinking, stupid jerks. I was near the Biltmore Hotel and golf course (located along either side of the canal), and had seen security/etc driving around in electric golf carts on my way down there earlier, and I was lucky enough to quickly find someone still doing this, on his rounds, I suppose. I flagged him down, and he was VERY helpful, much more than I would have expected.
I had already failed to lasso the trailer with my makeshift hook-and-cable (a metal-hooked bungee cord tied in the middle to a roll of nice tough ex-military parachute cord I carry with me to tie cargo down with), and with him there I did manage to snag it, and he tried to pull it out with his golf cart, but the bungee hook bent and came off the wheel spoke it had snagged, because trying to drag it sideways up the steep rough concrete was too much pull in the wrong direction--if we could have snagged the hitch end it'd be easy to roll up the slope. He bravely scrambled down the slope to some steps a few hundred feet downstream (the trailer was moving at a brisk walking pace in the water's current, fortunatley very close to "shore"), and grabbed hold of the trailer's railing, somehow managing to not fall in the cold water. I had not risked trying that myself because I was certain I'd end up in there with it, and be unable to get back out. However, it kept stubbornly refusing to pull straight up, with the current rotating it every time I got it almost right.
After a few minutes of this, I realized he really should be getting back to whatever job he had to do, and that he had already done so very much for me that he didn't have to do at all, so I thanked him profusely and let him go on. I kept trying, and eventually after another 15 or maybe 20 minutes, at a guess, I lined it up correctly and got it to the position I could pull it up the slope. But I was too tired to actually pull hard enough to lift it at all, and even at the best I'm not sure I could have--the trailer weighs by itself perhaps 30 pounds or so, maybe a bit less, and the car battery weighs a lot more than I like to think about, being mostly lead and watery acid. Then there is the water that had pooled inside the cooler, which while not a lot compared to the cooler's volume was still at least a couple of gallons, which is another 16 pounds. Add another 20 pounds for the rest of the junk I had on the trailer at that point. Ugh.
I was REALLY tempted to just let it go, go home, and build another trailer someday when I felt less depressed about it. But my bike's rear light module was on the trailer, because I always mount it on there so people can see the turn signals and such on the road no matter what cargo I might have that would block their view of them if the signals were on the bike's rear rack as usual. Not only would I need to buy more red LEDs I don't have the money for, but I would have a lot more work wiring them up and building them into a case, compared to just building a new trailer out of random junk like this one was.
So I stood there for a while holding the trailer in position and thinking, coming up all nothing, when two women come jogging down the path, and ask me jokingly how big the fish is. I was too tired to feel much of anything, but I just replied that it was my bike trailer someone had pushed into the canal, and I couldn't lift it out, and they quickly jogged over and grabbed the line with me and we all pulled, which got it out pretty fast. I thanked them even more profusely (if that's possible) than the first person, they started back on their way, and I was left with a wet trailer and having to fix a hitch that I didn't even know I had the parts to fix, yet.
I just got lucky on that, that I had several nuts the right size for the bolt, and that I paint my bike stuff dayglo colors, including the boltheads, which let me quickly happen upon the bolt itself near where the trailer had come loose, back before I had tried lassoing it. (My 8-white-LED helmet light is pretty bright flashlight at 120,000mcd and puts out some UV, so dayglo objects also fluoresce under it's illumination, which let me spot the bolthead easily against the random gravel colors and shapes, even though I didn't see the metal-colored parts of the bolt at all).
I decided not to trust the bolt alone, and tied both the bent-up bungee cord and some parachute cord between the bike's end of the hitch (fixed to the bike frame stiffly) and the trailer's front stem (which is welded to the trailer), so that even if the bolt broke or the nuts somehow came off again, I'd not lose the trailer. I really don't want to go thru that again. Nor do I want it to come loose in traffic, which would probably be even worse. I'm sure I couldn't afford to fix whatever vehicle damage would be caused by someone hitting it with their car. :(
With very little incident, I made it back home just fine after that, though I'm completely exhausted, and only sitting here typing this because despite being so tired that I can barely move my fingers, I can't get my mind to shut down and let me sleep. I can't even hold my head up--I'm using a stack of pillows to do that. :(