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Friday, September 25, 2009

Technical Difficulties, Please Ride By

The technical problems mentioned in the previous post about coastdown testing was that somehow the righthand nut on the rear axle had been very very slightly loose, but I was unable to tell that due to the placement of the bottom cargo rail plus the derailer. I thought I had it as tight as possible, but actually the wrench was hitting the derailer's swivel point and resisting, so I thought the nut was tight when it really had at least a half turn or more. With the cargo rail on there, the wrench would push against the rail and the derailer's swivel point, start to turn then slowly get resistance as the derailer spring compressed, then feel snug. With the cargo pod in the way, I can't really see that happening, so I thought I had it. :(

The effect was that the left front sidewall would rub on the frame, and because there is extra room behind the leftside axle in the dropout (since no derailer is behind it to stop it sliding up) I *thought* that the left side was loosening because of all the weight on it and slowly sliding up the open dropout, since it seemed to be happening after I hit bumps and whatnot.

After each test I went home to change the wheel/tire, and I had the problem with both the 24's, after swapping out the 26". The 26" had not had a problem, because I had put it on *before* I put the cargo rail on, last time I was working on stuff, and without the rail there the wrench can be placed on the nut differently and there is no problem with this kind of thing. But I did not realize that was what was causing it until too late....

I only had to "fix" it once on the 24" MTB/road hybrid test. I had to do it a couple of times on the 24" gray test, and it got worse faster (because I had probably been in a hurry changing it out). Then when I was done with the tests because it was getting dark, I went up to the store to get 40lbs of dog food, loaded 20lbs into containers in each cargo pod, and went home (about 6 miles total), planning to go somewhere else when I got the dog food unloaded at home.

So as I rode I kept fixing it, and the fixes became more frequent as I rode on, even though I deliberately shifted into lower gears and rode slower. That was my mistake.

Shifting into lower gears put more torque and pull on the chain on the right side, which was the loose side, so it kept pulling farther and farther forward. Each time I "fixed" the left side, I was moving it forward in the dropout just a hair, closer and closer to not being *in* the dropout anymore. But it was already dark, and I did not really notice that. Each stop I had to carefully tilt the bike onto it's side and try not to spill any dog food (the containers are closed and latching, but not spillproof if you suddenly tip them over; they're cheap), and I was paying a lot more attention to not losing my cargo than fixing the bike.

Bad idea. Plus I was getting frustrated that it was even happening, because I couldn't figure out how it could possibly work it's way loose like that.

I was about half a mile from home when I stopped the last time to fix it, and loosened the left nut to "fix" it again, and the wheel came out of the dropouts on *both* sides!

Suddenly I realized what the problem was, why it was happening, and that there was no way I could fix it till I got home and got my cargo out, because I'd have to take the rightside cargo pod off to take the rail off to reach the right nut properly. Wow.

I got it back together well enough to walk it home, but even just activating the motor on the teensiest amount of throttle to let it help me push the bike along (it's really heavy, about 180-190 pounds including that dog food and the containers and stuff I had with me right then!). If I did that, it immediately pulled the right side loose again, though at this point knowing what was wrong I was able to use a screwdriver and wrench as spike and hammer to push against the axle nut to get the wheel back in place. Then I walked it home that half mile or so. Yuck.

So major design flaw is revealed. As someone that came by as I was fixing it the last time pointed out, it's like the car you have to take the passenger wheel off to take out the battery (don't know if there is actually a car like that, but that was his phrase). Seriously hampers fixing stuff on the road, since while it can be done, it is a major operation and will take a lot more time than it should, just to tighten that nut.

Oddly, I did not have this problem before changing the central frame, so something in the angles of frames must have changed slightly despite me trying to keep that from happening, leaving me less space for the wrench, plus the newer derailer is a different shape and closer to the wheel nut than the old one was.

Two possible fixes:

--One is to carve out a bit of the bottom edge of the rail, so that a socket wrench can fit thru it to tighten the nut. However, that would still require loosening the bottom bolts of the cargo pod to get the socket onto the nut, unless I also drill a hole in the cargo pod that lines up with that nut and is large enough for the socket and extender. Plus I have to then carry a socket wrench, extender, and socket for those nuts, none of which I have to have right now. That is another couple of pounds or more to the bike weight.

--Two is to remount the rail itself higher, to give full clearance for the regular open-ended box wrench i already carry for this. But it would have to go at least two inches or so higher, to be able to reach it. I'm not sure how well it would really support the bottom of the pod at that point, since it would be near the middle of it.

For now, I don't actually have to do anything, because as long as I tighten it without the rail on there when installing the wheel, it should be fine. But should I ever have to fix the tire on the road, it'd end up being a major operation to do, and I really really don't like that idea. If I am riding in the daytime, it'll be hot and melty while I do it, and if I am riding at night (much more common) I risk getting stuck on some poorly lit area with who knows what kind of people waiting for just such a sucker as me to be stuck there as their prey. If the wheel is messed up as it was tonight, I can't even walk it home, since the sidewall rubs so hard against the frame that I can't push the bike against it!

So...somethings gotta change; I just haven't decided what yet. Probably it'll be option one, because it's simplest to do with the least consequences structurally.

I also need to change out the tires to the new slicks, and finish the testing.


  1. Yuck. My rack mounts slightly interfere with me tightening wheel nuts. I think you at least don't get flats anymore.

  2. So far, but eventually something will happen on the road that requires me to take the wheel out. When it does, I need to be able to do it without spending two hours at it, and looking like a junkyard exploded on the side of the road. ;-)


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