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Sunday, January 3, 2010

Chainrings Are All Evil

Actually, not so much evil, as just insufficient to handle the job on this bike. :( But first, some info and pics of the things I did to fix recent problems....

Considering what I started with, I decided to use an older less damaged wheel to redo. The pic below is of the one damaged almost three weeks ago. The bent axle is pretty clear

and you can even still see the rim bending a little, though I straightened it A LOT just to get it round and flat enough to roll down the road to get home.

The spoke hole damage is what forces me to change rims entirely:

Its' very bad, and holes all around the rim on the drive side are like that

where they started out flat/flush. None was actually pulled *out* of the rim, nor were any broken, but it's bad. I have not taken the cassette off to examine the hub. I just went ahead and redid the wheel using the old Roadmaster wheel that was last bent by a pothole (I think), and replaced it's bent axle with one from one of the Christmas parts bikes, and used a cassette from the other one.

An overview pic of the repaired bike (after today's failures but you can't see them in this pic):

I rode around the neighborhood for around 4 miles testing stuff out without any problems, coming back to the house after every little loop to check things, tie wires down, etc, as I made sure each thing worked.

The newly built wheel, using the stainless spokes. They seem to be doing better than previous ones, as I do not get the wheel flex I used to with the old thinner (and probably cheap steel) spokes that had been in that rim, when I turn, etc.

After a few miles the wheel needs semifinal truing (and will probably need it once more after a few more miles, as the spokes settle in).

The tire is not yet aired up in the pics above, which were taken with the bike upside down but camera held that way, too. :)

This is a chain deflector made to help hold the pedal chain about a millimeter away from the motor chain, as it intersects with it near the receiver rings, so they don't rub anymore.

It's made of a piece of my sister's discarded plastic cutting board (either teflon or nylon, don't know which but it works either way).

The clearance is VERY narrow.

I also decided to do the same where the pedal chain crosses under the motor hub axle, as sometimes in left turns the chain would rub and even catch.

Now it is MUCH quieter, meaning that it was rubbing against the motor chain a little bit even when it did not seem to be, and now is rubbing against the plastic but not making the little ticking sounds I could sometimes hear.

The clearance is a couple of millimeters.

The front brake really wasn't sufficient before, or wasnt' working well, not sure which. It had been a linear side-pull style, with the little metal noodle and all to redirect it to vertical. Now it is a set of center-pull, again off one of those parts bikes.

They're cheap brakes and I don't like them much. But they work better. Not good enough, but better. The hard part was that they require something external to the brake unit to push the cable housing against. Normally, that is a bracket that is part of the U of the fork, but that wasn't possible on this shock fork, or else pulling the brakes just compresses the shock, rather than braking!

The shock fork on that other bike has the bit built as part of the U, but that whole fork is flimsy--I can twist it with my hand, unlike this one, so I don't trust it on this heavy bike.

So I took a little black steel rackmount ear tab and bolted it to the brakemount/reflector hole on the U, then used a seatpost-mount tab for this style of brake off another bike, bolted sideways thru the rackmount ear upper hole. The bike cable housing is then pushing against the fork thru this, and it works very well with no visible flex.

It is still not enough braking power, and I still need something like disc brakes (possibly in addition to the rim brakes), once I can figure out how to design some, if I don't run across any on something scrapped out.

Another addition is a Stanley Tripod Flashlight. It's a Freecycle find, and was described as not working. Indeed it did not, when I got it, but a quick check inside found that one of the power wires to the LED board was never even soldered. The wire ran thru the hole, and there was hotglue from the factory to hold the wires down, but they missed soldering this one. Easily fixed, and voila!

For now it's just zip tied to my existing light.

It was daylight when I took the pics (noonish), so I don't yet have pics of it in the dark. I will have a separate post for it later. But it has a very good beam, though not nearly bright enough for most street use. For canal path or unlit roads, it would be fine, but where there are other light sources shutting down my eyes' ability to open up the iris, it's not enough to help very far away.

It lights up street signs EXCELLENTLY, though, when it is aimed high. Aimed normally, it'll show me the holes in the road fairly well at 20-30 feet.

Don't know battery life yet; it runs on 3AA batteries, and can have a set in each leg. Right now I have two sets of NiMH in there in parallel, one 2000mAh and one 2300mAh. The third leg holds a set of regular Duracell AAAs, with a piece of plastic keeping them from being used at the same time as the much lower voltage NiMHs. If the others die, I can take one out of each leg and pull the plastic out of the Duracell leg, and use them. Only doing this now because I don't know the lifespan of the light yet, and don't want it to suddenly die on me.

Once I figure out what the electronics driving the LED are, I may change it out for a brighter one I have, if they will handle the current it needs to draw and can be modified to do so.

As the Curtis is a 48V capable controller, I decided to also add the fourth battery:

For now it's just secured in the righthand cargo pod, until I can tell if it makes a difference. I have not yet wired in the chargers. This battery is wired in as the "top" of the pack.

While I was at it, I also wired the lights into the monitoring circuit, so the Turnigy meter can tell me about their usage. So far it takes about 350mA to run the CFLs at 48V, including the laptop adapter used as a DC-DC converter. It's only a little less on 36V. Turn signals take the same 2A-ish peak, dropping way down pretty quickly as they blink each time. The LED brake light is about 300mA by itself.

The curtis itself is mounted on the side. Even during a test where I put the front of the bike against a wall, and ran the motor at about half throttle, hard enough to spin the wheel in the dirt if I didn't lean on the bike, it didn't get even warm for the few minutes of the test. The motor itself warmed up quite a bit.

So either the Curtis is holding the heat inside due to the electrically-insulative pad it uses between the inside heatsinks and the case, or it simply isn't getting warm enough to notice.

The main keyswitch is this:

glued down into the top of the steering tube the handlebars mount to. Horizontal is off, and vertical is on. Have to turn it off to take the key out.

Since things fail, and I might need to reach it fast, I also wired this in series with the keyswitch:

It's the run switch from the old Honda scooter. I left the handgrip (throttle) off of the assembly, and just used it for the knob and the brake handle (and built-in weatherproof brake light switch).

Center is run, and up or down turns it off. Can be flicked with my thumb if needed.

Ideally I'd like to take the brake switches and wire them to a DPDT relay. One pole would be NC for the motor run line, in series with the keyswitch and the run/stop switch. The other would be NO for the brake lights themselves. It's just something I have to "get around to".

Mounted on the bottom/inside of that is the throttle pot. It's shown without the lever here for reasons best explained in a picture farther down.

Until I fab the other metal bracket for it, it's screwed in securely to the grip body on one end, and ziptie-clamped to the handlebars on the other end. It won't move in normal operation.

The lever runs parallel to the grip, so I can push it down with my thumb. To fully grab the brake handle requires letting go of the throttle, making it not quite impossible to power the motor while brakes are on, at least with the front brake and this hand. I could still do it using the rear brake and my left hand, of course, which is why I want to do the brake-cut-off relay.

But first, I have to makea new throttle pot clamp:

It's metal, not plastic, but it broke like plastic.

I can only assume I must have somehow tightened the set screws on it too much, although I am not sure how that would break it like this, something did. It came apart as I lightly pressed on it after I got home, so at least it didn't cause me a problem on the road. Since the spring return is done by pressing against this black piece, if it had happened on the road it would have left the throttle "stuck" in the last position, requiring that I manually grip the shaft and turn it.

Now for the ugly part. :(

Less than a mile or so into my trip, another of those half-second-to-destroy-things failures happened, again with the chain derailing, but this one was caused by my fiddling with what had been perfect alignment, in order to fix the pedal speed problem (having to pedal really painfully fast to help the motor at any high speeds), and the pedal-chain looseness problem due to being a half-link too long or short, because of tooth count on the pedal chainring.

I thought it was perfect this time, but apparently not. What basically happened was the motor chain derailed to the left of the motor receiver ring, got caught between the ring and the outer guard of the ring, which being not only metal but actually part of the crank spider meant that it was strong enough to then force the ring inward slightly.

The teeth on that ring must've caught the outer edge of the pedal chain, which then was pulled onto it, bending it in even further since like the motor chain it has no slack.

Then it bent the pedal ring outward, and the bike STOPPED. That all happened so fast I didnt' have time to prevent it, just like the other disasters of this type.

Fortunately the pedal ring is a 3-ring set now, so I was able to take the extra link back out of the pedal chain, put it on the middle ring, bend the motor ring back out of the way, set the rear drivetrain to the front granny ring, and pedal my way the rest of the way to work and then home later.

So I guess it's time to

A) make solid steel chainrings to use with the spiders (have to find some of my scrap plate steel of the right thickness, print a drill pattern from the computer and glue it on, then drill it out, file it, and then harden it somehow).


B) find a way to ensure perfect alignment. I don't really know how to do that, as I was SURE it was aligned already, and it worked for almost 5 miles with zero problems, then suddenly BLAM.

Nothing shifted around or is loose, either, even under motor tension, that I can see, but I know conditions while moving on the road are different.

Either way, I'm guessing it's getting time for CrazyBike3, 1000-mile mark or not. :(

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