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Saturday, September 6, 2008

Pics Of Parts, and Progress

I'm still working out a few things, but today's post includes pics of progress on the recumbent-from-scrap bike, as well as pics of donor frames/etc similar to what I used to build it (since I did actually forget to take pics of them before cutting up).

First up is a side view and front/rear views of the parts so far completed:

It's propped up on bricks at the shock-hinge point, with just a rusty old spring in the approximate spot where the actual shock will go. The seat frame is only set on top of it, as there are as yet no mounts for it. Those still have to be designed and made, since I'm trying to come up with a decent vibration-absorbing mount (the shock probably won't take up enough of the vibration for my liking--the one on my Columbia's seatpost sure doesn't).

It's kind of long, but not as long as I had been afraid it would end up, partly because I am going to mount the rear shock alongside the frame, rather than between the former seatpost and back of the seat. That gives me back 8 inches of clearance, as now I only need to allow for frame movment space rather than that *plus* the actual shock hardware and mounting points.

This is a pic of it laying on it's side, in better light.

These are the wheels off the red 20" frame in a later pic. They're both aluminum rims, which will help with weight. The rear wheel in this (on the left) has two things I really want to use: a tubeless foamcore tire (no worries about front flats, thus no need to carry that second spare tube I'd otherwise have to have), and a single-gear reversible freewheel, which I need for the motor's freewheel. I just have to get both of them off the existing wheel, which is proving quite difficult, as I don't want to damage any of the three things. :-(

These are some possible cranks and chainrings I could use for the pedals up front:

I will most likely opt for the longest cranks (one of the middle two) and the smallest of the single chainrings (on the upper left), as that gives me the best initial torque on my drivetrain, which I'll need for hill climbing, as there's no standing-on-the-pedals to get that with a recumbent, or at least not with this design.

There won't be but one chainring on the pedals, since I don't want to put the derailers/shifters up there for a few reasons. First, it precludes my anti-theft idea of quick-removable cranks. Second, it adds complexity in an area up front that would be "first contact" in the event of a front-impact, causing less likelihood of riding away from a minor crash (something I expect during self-training on this bike, in non-trafficked areas and paths). Third, it's uglier with more stuff up there--I'd like a cleaner look wherever possible. :-)

So the other chainrings might be used, but they'll be down underneath (where yeah, there's less ground clearance for them, but more place for me to put stuff out of my way), at the first or more likely second power-transfer point. Probably the one just in front of the rear wheels, just under the shock-pivot. I'll probably use the common three-ring design, as most of my shifters for the handlebars were made for that number.

The 20" wheel vs 24" shock fork dilemma produced the following solution:

The left pic shows the light blue 20" fork I wanted to use, but which is A) broken inside where I can't get in to fix it right now, and B) at least a whole pound heavier than the 24" fork that works fine (and has more shock travel to boot), in about the position it would be if it were there instead of the 24" one, which is the darker blue one.

The middle pic is a closer shot of just the 24" fork and wheel, with my modification. I cut the rear wheel mounting tabs off of what was left of the light blue donor frame (the one that provided the curved down tube plus headstock), which were similarly made as the ones in the pic on the right of another small 20" frame.

Then I put both tabs in my vise (which happens to have the threading bolt between grip halves that exactly match the axle groove in the tabs) and clamped them together such that the axle grooves were perfectly aligned. I ground the outside edges of the tabs down to be perfectly parallel wherever they weren't yet (symmetrically manufactured these were not!), both for looks and for ease of parallel mounting on the 24" fork.

I scraped and sanded the paint off the front edge of the 24" fork to provide a clean surface to weld the tabs to.

I put the 20" wheel in the tabs and hand-tightened the nuts to clamp the tabs as parallel as I could to each other, then held the wheel into the 24" fork so that the wheel's rim lined up with the brake pads on that fork, temporarily super-gluing the tabs to that spot at each end of the tab--the glue will hold it just long enough to tack weld it.

Once tack welded, I made *sure* that the wheel was as perfectly parallel as possible to the forks, so the brake pads would line up and whatnot, and it would steer straight (there is some adjustment play in either one without a great deal of trouble, so it did not have to be absolutely perfect), then took the wheel itself off, and fully welded the tabs to the fork.

Now I have a way to use a 20" wheel on my 24" fork without having to modify the shock portion of the fork, and the shocks still work like they did before. The center of thrust and the trail of the fork/wheel combo is of course different, but it still operates more than well enough for what I wanted. I still wish I could mount it more straight-up-and-down, but there are a number of reasons I can't, with the parts I have available, with the design goals I have in mind. I could do *some* cutting-and-rewelding such as on the headstock to change it's angle, but I don't want to do that unless it's absolutely necessary, as I'm sure my welds are not as good as the originals, even on the cheap junky frame I'm using as a donor in this case. There's not really anything I can do on the shock fork itself to make it shorter than it already is, to allow a steeper angle, without way more work than I think I can safely do to it (which is part of the reason i wished I could use the 20" shock fork to start with).

Now for some pics of donor bikes similar to what I've used:

The lefthand pic is of 3 20" bikes that have most features in common with each other and certain parts I used already or will use later. The red bike will donate it's seat tube and bottom bracket as the front pedal-mount tube and bracket for my removable/adjustable pedals. One of the long seat tubes and some other seat-mounting pivot hardware, along with a quick-release seattube bolt will mount it all to the headstock up front. It will also donate it's headstock to the actual steering handlebar mount for under the seat. That headstock will be mounted as vertically as possible in the "U" formed at the front of the pink ex-front-fork that's under the seat of the recumbent. It's likely that some of the thin rear triangle tubing from it will become parts of the seat mounts.

The middle pic shows a silver and purple 24" very similar to the brown metallic one I used for the rear-triangle of my recumbent. This silver/purple one also donated it's front shock fork. The one on the brown bike was bent up and all but destroyed on the righthand side, though the left side is possible usable separately (and may become part of the rear shock system).

The righthand pic shows a Huffy 24" almost exactly like the ones that provided the pink and the purple U-shaped forks forming the middle of my recumbent. The two donor bikes also gave their rear triangles to make the sides of that cargo trailer in earlier blog posts, and I've used most of their other parts here and there along the way, too. Their down tubes are almost all that's left, and those will likely become parts of the seat mounting system on this recumbent, and possible parts of the rear shock.

Pics of other assorted parts:

The left pic is a bunch of handlebars, some forks, a rearview mirror that was in a bag of stuff I got last week, etc. Parts of a couple of those handlebars will be put together (probably have to cut and weld) to make my under seat steering bars and grips.

The fork on the left side of the righhand pic is the upper remains of the wrecked brown bike mentioned above. There is only one spring, as the other was damaged along with the outer casing. The fenders and chainguard might end up on this bike; I am pretty sure I'll need them. THey came off a pretty old Huffy Sportsman frame that looked unsafe to actually restore to use.

So there's this week's eye-candy, with enough verbiage to spoil it for you. :-)

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