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I just recently got a single speed with a flipflop hub and got the bike shop to switch it to the fixed cog. While riding around, the gear came loose on the back hub and almost flung me off so I had to bring it back to the shop to get them to tighten it.

Does anyone use any thread locking fluid on the rear wheel gear to keep it from slipping on the hub or will tension from the lockring keep it secure enough?

And if anyone has used thread locking fluid, did they have any problems getting a polymerization reaction to occur due to a low electrochemically in the hub/cog due it being made from aluminum or some other lightweight material?

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Does your hub have two threads (one righthand for the sprocket, and one lefthand, smaller diameter, for the lockring), or is it a freehub - only one thread - adapted for fixie using the "suicidal" configuration already mentioned? –  heltonbiker Mar 29 '12 at 20:49
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3 Answers

up vote 4 down vote accepted

If you have a fixed gear type hub, not a dual freewheel flip flop hub, and a lockring which is properly installed, there is no benefit to using threadlock on a fixie hub.

Thread lock works just fine on aluminum, although it tends to cause stripped fasteners because it requires more torque than most aluminum fasteners can handle. With a fixie lockring, though, there aren't enough threads (surface area) to really benefit from a threadlocker.

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I suspect the issue is that he's using a suicide hub without a lockring. –  Stephen Touset Mar 29 '12 at 19:16
    
You mean running a fixed/free flipflop with fixed cogs on both sides? Ow. They make fixed/fixed flip-flop hubs. I suggest buying one. –  Kohi Mar 29 '12 at 23:36
    
That is possible, and to be honest it was my first thought. But the OP does mention a lockring specifically. A suicide hub wouldn't have one, would it? –  zenbike Mar 30 '12 at 4:59
    
@zenbike I think they call it suicide hub even if it has a lockring, and even if it is glued, because there is no real "mechanical" locking action, only friction between materials, since there is only thread in one direction. That would mean a force large enough will unscrew everything out. What people manage to do (myself included) is to have enough friction to hold it in place for a given use, but it is never 100% sure it won't come out... –  heltonbiker Mar 30 '12 at 13:43
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My fixie was bought second hand, with this configuration:

  1. Regular threaded hub for freewheel (only one thread);
  2. "Glued" sprocket;
  3. "Glued" lockring, probably taken from a bottom bracket, a headset, or something similar.

That is, the suicide hub already mentioned...

I tend not to skid, but I use the "deccelerating" function of the fixie a lot, and it never came out. I guess who mounted the kit (probably some acquaintance of the guy who sold me the bike) made it right, with lots of torque on either the sprocket and the lockring, and enough amount of good quality locking glue over clean surfaces (by the way, steel cog, steel lockring, aluminum hub).

I had a broken spoke on the drive-side (cannot insert another, cog gets in the way), and I think I will not risk disassembling and reassembling this glued configuration, because I think it is too risky.

I am only riding it yet because, I think, if it is not broken, don't fix it (pun intended).

So, answering you question: yes, I use such a hub, ride daily with a bit of "emotion", and it is working great, never came loose. But I plan to switch to a better quality hub, assembled the right way, very very soon. Piece of mind.

(by the way, since I have a relatively firm double-wall semi-aero rim, I keep riding even with one less spoke. Actually, it is wrapped around other spokes. Thank God centrifugal force exists!)

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If you have a broken spoke, then "It's broke. Fix it." –  zenbike Mar 30 '12 at 5:03
    
@zenbike You're absolutely right. I'm going to buy a new hub, indeed. –  heltonbiker Mar 30 '12 at 13:39
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A better solution if you're using a suicide hub configuration (a freewheel hub with a fixed cog) is to use an old-school bottom bracket lockring to hold the cog in place. It's not ideal, as the lockring threads aren't reversed, but it's better than nothing.

Even with this setup, I'd still recommend re-tightening frequently.

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If it's glued then every time you tighten it you're breaking the glue and hoping it reseals. I'd be more inclined to pedal backwards firmly before I started riding anywhere in the hope that if it was going to break it'd break then when I'm stationary with my other foot on the ground. Develop that as a habit and it's marginally less unsafe than just hoping for the best. –  Kohi Mar 29 '12 at 23:34
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