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Rear Axle Bent Yet Again
#1
I had a bent rear axle and replaced it with a standard steel axle. Now I find about a week after I did that, that this one I have now is bent.
I was wondering if anyone had some enlightenment on what could be causing it (I am a Clyde rider, so that could be it, along with the numerous hills I have to climb here). Both axles were bent at the start of the threads on the freewheel (drive) side.

More important, any enlightenment on what I need to be ordering to solve this problem? I.e. a rear axle that isn't such crap?

Edit: Added a picture of the axle if that helps.
[attachment=52]
Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
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#2
No ideas? I thought of another possibility today. It turns out I got a new axle off of a salvage bike and put it on and noticed that I had to wedge it in. I replaced the locknut of one of the cones with a thinner one, it popped right in there tight (no play between the frame and the locknuts) and it seems to be fine (so far). Positive thing out of it is if this one fails I know what will have caused it.

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
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#3
It turns out I got a new axle off of a salvage bike and put it on and noticed that I had to wedge it in.
Which was discovered to be bent when I pulled the wheel promptly after a ride on it.
So probably not the axle itself, since this is now the third axle that's turned up bent? I know the frame on this bike has been abused. So could this be that the part of the frame where this axle goes in is bent? Or another possibility?

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
Reply
#4
Is it a quick release? Doesn't look like it, but if it was, switching to a solid axle should help.
Based on where it bent, I'm assuming you have a freewheel. One solution is to switch to a cassette hub. Cassettes have the drive side bearings out much closer to the end than freewheel wheels do. So there's less distance between the frame and the stress point, so much less likely to bend.
Or a bigger rear tire to soak up more of the road impact.
Any downhill mtn riders out there know if they make heavy duty axles for downhill bikes? I think a higher end chromoly axle will be stronger than a cheapo plain steel one.
I doubt the dropouts would cause this, though they may have gotten bent some each time the axle bends. I'd check/straighten next time you have the wheel off.

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#5
Quote:Is it a quick release?
No.
Quote:Based on where it bent, I'm assuming you have a freewheel.
Yes. But I'm not sure that's part of the issue. At least not yet.
Quote:Or a bigger rear tire to soak up more of the road impact.
As I said in another thread here, the tires this bike is running is .45" bigger than the rim. I'd think that'd cause more issues than it would solve?
Quote:I think a higher end chromoly axle will be stronger than a cheapo plain steel one.
I saw that, but if I went that route, I'd want to make 100% sure that it would fix it. Especially since there's quite a monetary difference between the two.
Quote:I doubt the dropouts would cause this, though they may have gotten bent some each time the axle bends. I'd check/straighten next time you have the wheel off.
I did check this and found the drive side drop-out to be rather bent. I used a 3/8 bolt with nut on each side to check, and bent the drive side back with a pair of pliers so the ends of the bolts would rub together and the dropouts would be relatively level with the frame. I don't know how reliable this method is, but it was the best way I could think to check it. The turning of the wheel was rather bumpy and the freewheel visibly shifts back and forth, so I'm thinking that might be close - just need to get hold of that axle to be able to check more.
The derailleur mount turned out to be loose when I got that back on, but it doesn't look like there was ever much to hold that on anyway (a screw with a slot nut designed to go into the drive side dropout) . Any thoughts on that would be much appreciated.

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
Reply
#6
Based on where it bent, I'm assuming you have a freewheel.
Yes. But I'm not sure that's part of the issue. At least not yet.

I can't promise it will fix it, but it would help. On a freewheel hub, the right side bearings are farther away from the frame than on a cassette hub. So your weight bears down on the axle closer to the center, so it is easier to bend it. But this is a pretty expensive fix.
A bigger tire MAY soak up more shock than a smaller one (all other things being equal). Ultimately, your weight is the same, but the tire does absorb some impact so I would think a bigger/lower pressure tire would protect the axle somewhat from spikes in force. But it will also affect other aspects of ride quality.
It sounds like you did a good job on the dropout. I'm sure it's best for these to be straight, but I doubt it caused the axle to bend. The axle is stronger than the dropout and I'm guessing the dropout bent when the axle bent. The derailleur mount just has to hold it in place until the axle nuts clamp everything down.
Not sure what you mean by the wheel rotation being "bumpy". If the bearings are rough, they may be damaged as well. I'd inspect and change out when you do the axle. Note that if the cups in the hub shell are damaged, you usually have to change the hub anyway.
I'd try a stronger axle first. No guarantee it's going to fix it, but the root of the problem is that you're putting more force on the axle than it can hold without bending. I'd think a stronger axle should help.

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#7
The derailleur mount just has to hold it in place until the axle nuts clamp everything down.
Actually it's not even doing that. That's why I was asking about it. I didn't find anything good on search to describe how it's supposed to mount. It seems the nut was stripped, but I want to be sure that I'm trying to mount it right before I try to track down a replacement.

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
Reply
#8
Be easier if you had a picture, but most of these derailleur hangers are fairly simple. There's the larger C shaped plate that goes on the outside of the dropout. A bolt goes through it to a smaller piece that fits into the dropout from the back. The smaller plate often has a step in it made so it fits partially into the dropout's cut out to "lock" it in place and prevent rotation. If the bolt is stripped, it makes putting the wheel on more of a hassle. But it is the axle nut that is really holding everything together. You would just have to get the derailleur lined up where it's supposed to be while doing the same thing with the wheel and then tighten everything down.

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#9
It was indeed a stripped out "C shaped plate" or "nut". Getting a new one fixed it. Thanks for your time.

Why is it that they make adult bikes that'll generally work for 5'9" or above, yet when you pedal these same bikes they only work for someone who is 5'4" or so?
Reply


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