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My fixed gear bike has a track fork with a chain tensioner, and uses Pitlock's solid axle nuts to secure the wheel in the dropout, though I had similar issues with the stock nuts.

After tightening the nuts with a torque wrench to the 260-390 inch-pounds recommended by Park Tools, the wheel appears secure, and will typically be fine for weeks at a time.

Inevitably however, the rear wheel slips forward on the drive side, perhaps by 0.5-1cm. This produces considerable slack in the chain, though it's usually still ridable in the short term.

My guess is that this is happening under sudden braking, which I've heard can cause slippage when the nuts are insufficiently tight. Indeed, I usually notice it after having to stop sharply somewhere along the ride.

Is this normal, or an indication that the torque specification I'm following is incorrect? If normal, is this preventable with some maintenance (for instance, is it caused by gradual slippage?). If it's not normal, what's the cause? Are there perhaps different torque specs for a fixed gear bike?

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3 Answers 3

This can be a fairly common occurrence with a fixed wheel bike. It may depend on a few different things, ie what sort of nuts you are using, how tight they are, what style of dropouts, and what the dropouts are made of.

A different sort of nuts may help. eg something with serrated nuts or washers could grip better. Also you may be able to tighten the nuts more, maybe a bit higher than what Park recommend.

Probably the best option is to use chaintugs. These fit on the dropouts, and have some sort of screw to hold them in place. So this stops the axle from moving forward. Usually you only need one, on the drive-side dropout, though you can use one on each side if you want.

One example is the Surly Tuggnut.


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Interesting point about only using one, on the drive side. But that seems like you are just asking for trouble without any benefit. (You only should brush the teeth you care about, right?) –  David James Nov 10 '13 at 5:23
Seconded about the chain tug but agree you only need one, the drive side is the only side under tension directly from the chain, obviously. One each side looks prettier though... :-) –  user8565 Nov 10 '13 at 8:48
Interesting. By chain tensioner though, I meant that I already have tuggnuts. Possibly I'm using them incorrectly however. Is the idea to tension the chain with the nut, and then tighten down the main nuts, or is a different procedure needed? –  John Doucette Nov 10 '13 at 14:09
A chain tensioner normally refers to a sprung jockey wheel thing used to take slack out of the chain (it wouldn't help here and isn't recommended with fixed gears anyway). If you have chain tugs though, figure out how they're slipping, because they shouldn't. –  Useless Nov 13 '13 at 0:44

Another potential cause of your problem might be your axle being wider than your frame.

I had that with an old steel framed road bike and a new wheel and it was subtle enough that I didn't notice, but my LBS pointed it out when I complained of a similar phenomenon. If that's the case you may be able to cut the axle down to fit.

I actually avoided that and simply found a different skewer since this was a QR axle that seemed to be able to cope better with the frame/axle.

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It's not clear that this would be a problem for a solid axle, since the retaining nuts are threaded on (vs using a skewer) and there can be inches of axle sticking out without affecting the holding power of the nuts. –  Daniel R Hicks Nov 12 '13 at 13:29

I suggest that you recheck the torque at regular intervals. If the torque is less than it should be then the nut is working loose somehow. This could be due to vibration, dropout material expanding/contracting with heat/cold, meddlesome kids, etc.

One solution might be to use a threadlocker - a weak glue to stop parts from vibrating loose. The recommended type for bicycle use is blue. I believe you can also get a red type which is stronger, but it might mean you need power tools to undo the thing.

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