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Earlier this month I had a issue with a broken axle. It was the original that was sold with the bike and lasted around 5,000 miles. I went to my LBS and bought a new axle (unbranded, labeled, etc, paid $13, came with cones, spacers, and hardware). I did the install myself and had everything adjusted nicely. The next time I rode it was on my commute to work, but I didn't get 4 miles into it when I found that I bent the axle.

I took the wheel to the shop but they wouldn't do anything about it since I didn't have them do the work. However, I figured this was a fluke and asked them for a new axle and to true the wheel. Once again I did the install of the axle and only got 15 miles out of it this time before bending it. Before I got home I felt the wheel get stiff, but it stayed true.

The question is what will be a cause of bending 2 axles in 20 miles?

I think the guy at the shop said it was a cro-moly axle (while talking to another person today at the shop, these may not be), and he couldn't believe that I bent it. If so, where would such an axle fall in the quality hierarchy?

Or is my hub toast?

While the wheel was being repaired, I swapped to a new original wheel for about 2 weeks. I have not had any issues with it, but I wanted to keep it as new as possible.

Reading other questions I saw a comment that said not to use a hub where the bearing was catching. I did have one in this wheel but I figured since it is a cheap wheel I would just burn it up and move on to a better one. Besides, it has lasted 5k miles without issue to this point.

The bike in question is a 2008 Schwinn High Timber with Joytech freewheel hubs. I do use a trailer with this bike using a Burley axle hitch. While I had the hitch installed on both axles I bent, I did not have either trailer hooked up to them.

Something I would like to note is that when I removed the first bent axle (axle #2) that the cones on it had a wavy bearing track. I didn't think too much of it, and I put them on axle #3. Only having a few miles on them shouldn't have made a difference?

  • Um, how should i put this... are you fat? – Batman Aug 29 '14 at 1:20
  • I'm currently 86kg, this being my low for a some months. My heaviest was 106kg. Average would be 92kg. While I may have some belly left to loose, the answer is going to be a no (I don't think so). – BPugh Aug 29 '14 at 1:31
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    Most likely cause is the QR is not done up tight enough. – mattnz Aug 29 '14 at 1:35
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    @mattnz, nutted axle in this case. The bend is happening inside the hub which is causing the bearings to tighten. I have other wheels that use QR, so I know how tight to make them. – BPugh Aug 29 '14 at 1:38
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    I would bet that the right-side cone is screwing itself on tight because the lock nut was not tightened against the cone well enough. When this happens the bearings lock and exceptional force is placed on the axle, possibly enough to break it if you continue riding after you feel the wheel lock. By now the hub races may be damaged. – Daniel R Hicks Aug 29 '14 at 2:39
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The reason for the bent axles is primarily due to your riding a bike with a freewheel. Freewheels (as opposed to a freehub) have a length of unsupported axle on the drive side of the bike that is vulnerable to bending. That is the primary reason why freehubs were invented. As the bike industry moved more and more gear sprockets (6, 7, 8) this meant a wider cog and longer unsupported length of axle. It is amazing how many cheap modern bikes (Schwinn sold out their name for use on low quality bikes long long ago) are still using freewheels which are an obsolete technology at this point. http://sheldonbrown.com/freewheels.html

Improperly adjusted or worn bearings are not considered a major factor in having a bent axle unless the bearings are very destroyed and the wheel is not working normally. Bent axles are due to load. So, you using a heavy trailer and being a larger than average rider, the axle is more likely to bend.

Get a strong well build wheel with a freehub. If you want an axle of CrMo then make sure you are getting it. There are OK inexpensive wheels for $40 so at $15 per axle replacement (excluding labour) it really makes more sense to not be replacing axles. Joytech is a cheap hub. Buy a good quality wheel that is worth >~$100 and you will save time and money in the long run.

I'm curious what you mean by "bearing was catching...just burn it up" That sounds like you may not be adjusting things properly. Maybe review some insructions on doing a hub overhaul or go down to your local recycle a bike shop for some hands on learning?

I'm also curious how you could tell specifically by the mile when your axle bent? Normally a bent axle is hard to notice unless the wheel is removed.

I find that rear wheel axles even of freehubs can be hard to keep straight. My old parallax hub with an 8spd freehub would always have a slight bend when I took it off to examine it and this resulted in uneven bearing wear. Probably due to me carrying very heavy trailer loads, passengers etc. North American bikes are often designed for sport rather than long term utility so even a tall person may be outside of the design for the bike. My solution was to get an old new XTR titanium axle that was laying around in a parts bin at a shop I did business with. Since then my rear wheel hub has stayed well adjusted :-)

  • Freewheel hubs were used for decades, on all kinds of bikes, and bent axles were not a serious problem with them. – Daniel R Hicks Aug 30 '14 at 12:29
  • "bearing was catching...just burn it up" What I mean by this was that after I got he wheel back together and gave it a spin, I could feel a spot where bearings was catching something and transferring motion through to the axle. I figured that since it was a cheap wheel I wouldn't worry too much about it and just use it up. As for telling what mile when the axle bent? I have put thousands of miles on it, so I know quickly when something is off. When the axles bend, they happened to move the cone on the one side and squeeze the bearings. This had the same effect as applying breaks. – BPugh Sep 1 '14 at 6:06
  • All that you (and Brown) have said about freewheels make since, and I have some new modern wheels picked out should I have to, but I'm also suspecting that the switch to freehubs has allowed axle suppliers to tweak their metallurgy with side-effects. Unfortunately I have lost a ball when trying to install the chro-moly axle, so I can't tell you if it is the case. However, I have 2 OEM axles: one that broke at 5k miles (with the fatter me using it the most), and another that has served me well this whole month. The bent ones so far haven't had a chance to be abused at all, just babied. – BPugh Sep 1 '14 at 6:26
  • @BPugh - Balls are cheap to replace, and any decent bike shop sells them. You just need to replace all at once, if the bearing has any sort of miles on it. – Daniel R Hicks Sep 29 '14 at 12:27

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