Wheel = Fail
July 19, 2008 2:07 PM   Subscribe

Why did my bicycle wheel flop about?

Well, I ended up getting a racing bike after posting this question - for various reasons (mainly cost), and I'm loving it!

However, the front wheel is radially spoked. This causes some spokes to loosen off on occasion, so I did some research and discovered that Sheldon Brown recommends using threadlocker. So, today I re-trued the wheel, using 1342 from ThreeBond. Bad mistake! I set off for the Dunwich Dynamo tonight, and a minute after some heavy braking, the spokes all loosened, to the extent that the rim started flopping about. No ride tonight then.

So was the great Sheldon wrong? Doeas anyone else have recommendations on how to fix this? I've previously built and trued wheels, with no problems at all. The only difference is they've not been radially spoked and I've always used lube instead of threadlocker.

I can only guess that the braking warmed the rim and spoke nipples, causing the threadlocker to re-liquefy.
posted by Kiwi to Sports, Hobbies, & Recreation (6 answers total)
 
Hmm, there are versions of threadlock suited for automotive (high-heat) applications, so I wouldn't assume that the threadlock heated up to the point of liquification.
posted by zippy at 2:23 PM on July 19, 2008


Did you relieve the stress on the wheel after you trued it? Tightening the spokes makes then want to twist. After you build a wheel, you need to relieve the spoke tension; the most common method is by laying the wheel on its side and pressing hard on the edges of the rim. You'll hear it creak and pop; that's the spokes "de-rotating".

No amount of loctite will prevent the spokes from loosening if they're under the twisty tension (I don't know the technical term for this).

Did your bike come with the Khamsin wheelset, or a different one? The Khamsins are decent training wheels. You say you've built wheels before, so I'm guessing you know what you're doing, but if this happens again I'd drop the wheel off at the shop and have a second opinion.

Good luck, and let us know what the problem was when you've got it sorted out.
posted by spikeleemajortomdickandharryconnickjrmints at 2:34 PM on July 19, 2008


What's the curing time? It wouldn't surprise me if they recommended 24 hours (in fact it is 24 hours, according to the FAQ).. Also, I expect the thread locker needs to penetrate the thread very deeply to be effective, and I'm not sure how you do that with spoke nipples - you really don't want to completely loosen a spoke in a completed wheel, and putting the thread locker on initially would cause trouble for final adjustments unless it cures very slowly indeed.

Wild speculation.. I wonder if some thread lockers just don't grip certain substrates very well.. Or, maybe the thread locker doesn't like a lubricant that was previously on the spokes.


I think your talking about two different things spike-y-mints..

To eliminate the tendency for spokes to spring back under rotational tension, you should over adjust and then back off a little. Leaning on the rim is probably a stress relieving step. Basically, when the spokes have been adjusted, they'll need a chance to settle into their new arrangement. So, best to give a wheel some serious push in various directions to get it to settle in while it's still in the shop. Followed by further adjustments as needed.
posted by Chuckles at 3:24 PM on July 19, 2008


Also, the threads on your spoke nipples might have had some grease applied to help reduce their tendency to twist the spoke when being tightened.

Use a degreaser rag/toothbrush and clean off your spoke threads next time? Just don't expect to be able to easily adjust your wheels ever again...
posted by anthill at 3:49 PM on July 19, 2008


or: yeah, what chuckles said.
posted by anthill at 3:49 PM on July 19, 2008


Still not sure what caused the original problem, but on reflection the whole enterprise was a bit of a botch, involving:

Dirty (possibly oily) spoke threads,
Insufficient curing time (well spotted Chuckles),
Insufficiently tightened spokes.

I was worried about over-tightening the spokes as I have had problems with doing this before; I was over-reliant on the threadlock compound to hold it all together.

Yesterday I burnt off all the threadlock over a flame, re-built the wheel with no threadlock or oil, and frequently relieving the spoke tension while truing. Made sure it was nice and tight. It seems to be holding up...
posted by Kiwi at 2:43 AM on July 21, 2008


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