Road Bike, Cycling Forums banner

1 - 9 of 9 Posts

·
Causeway Commuter
Joined
·
6 Posts
Discussion Starter #1
I know it's cheap. I know that the cog can unscrew from the hub (it did once. I stopped by using these things left on my bike from the last person who had it. Back in the day I think they called them "brakes.")

But seriously. I put the setup on my normally singlespeed conversion and rode it around the block a few times fixed. I had not ridden a fixed gear bike since 1968. It seemed fun, so I now I'm rebuilding the wheel. When I got the bike (free from a person who had it hanging in their garage for 15 years) it had a bent back wheel and a good front wheel. I had an extra wheelset, so I made a cassette singlespeed and put the wheels on the bike. To make it fixed gear, I'm taking the good front rim and building it onto the old freewheel hub.

When I first screwed the cog onto the wheel, and rode it I attempted to stop using my pedals. The cog started to unscrew. I screwed it back on, rode a bit more and gave it as much torque as I could while riding. The cog stayed put the next few times I tried stopping. So far so good.

So if I'm keeping the brakes on the bike (I'm cheap, but not crazy) is there a big problem with using the old threaded hub when I want to ride fixed (I'll still have the wheel with the cassette hub when I want singlespeed).

And finally, should I use locktite when I screw the cog on. If I do, will I ever get it off?
 

·
Registered
Joined
·
2,633 Posts
I ride as you described without problems.

I use brakes and the cog has spun off once in 3 years. I started using Loctite after that and have removed the cog by holding the wheel upright and carefully stomping on the chain whip.
 

·
Registered
Joined
·
5,524 Posts
Shimano-Campy

After the brakes/no brakes thread, this thread is the next-closest fixie equivalent to the Shimano-Campy "debate." You know the risks. It could work just fine if you're careful and you use blue loctite, but there's a chance that your cog will come off, throw your chain, and send you into a hard crash. Religiously using the brakes will help reduce that risk.

Loctite is working for RUSA. For me, it's worth spending the small amount of money on a new hub and lockring to reduce the risk of spending a huge amount of money on a new set of front teeth... but that's just my take on the risk-to-benefit balance. Enjoy your fixie and ride safe.
 

·
Causeway Commuter
Joined
·
6 Posts
Discussion Starter #4
This might sound like a really dumb question, but how does throwing my chain cause me to crash if I have brakes?
 

·
Registered
Joined
·
14,713 Posts
Not a dumb question

If the cog unscrews at high speed, the cog and chain can jam, locking up the rear wheel and causing an uncontrollable skid that will result in a crash, regardless of brake use. Using the brakes rather than back-pressure to stop will make the whole scenario less likely, but the brakes won't help if you do throw it.

PdxMark is right about this being an endlessly debated topic. Personally, I'm with RUSA (actually, I ride with him occasionally) -- my fixies have regular freewheel hubs. I clean the threads well, use lots of Loctite, and thread the cog on very tight. I've never had a cog loosen. But I use my front brake for any major braking effort.
 

·
duh...
Joined
·
9,658 Posts
I've done it, with red loctite and a BB lockring. Got all anal and marked a line on the cog and ring with a sharpie, so I could easily check if there was any movement. In the end, couldn't stand the insecurity of knowing that it *might* someday loosen, and got a real track wheel.
 

·
Arrogant roadie.....
Joined
·
4,232 Posts
Here's an idea somebody else came up with-use a snotload of Loctite 680 (nothing weaker, has to be 680), but mount it on the left side, switch your cranks (use loctite 242 on the pedals if needed). That way, you'll only ever spin your cog off when pedalling. Much safer this way.

Or better yet, build a wheel...
 

·
Steaming piles of opinion
Joined
·
10,503 Posts
With brakes and a converted freewheel hub, there's not much threat to a cog unthreading. You'll know the instant it pops loose, and can get the legs going forward before the wheel takes the six turns or so it will take to get it free. At the same time, you can brake or move on as the situation warrants.

The time for fear is when using a flip-flop hub with a fixed cog on the non-lockring side. Then there's not enough clearance, and the unscrewing cog will jam into the stays to a very bad result. On a converted freewheel hub there's more clearance to the stays, and generally more threads on the hub. So you have more of a chance to catch it before it unscrews, zero chance of it screwing into the stays, and lower chances of a jam-up if it does spin free. In summary:

Stupid no matter what: Fixed cog on freewheel side of a flip-flop. Lockup in waiting.
Fair if using brake(s): A converted freewheel hub. Not great, carries some risk, but not a death trap, either.
Best: A proper hub with a reverse-thread lockring, then no worries.
 

·
Registered
Joined
·
2,633 Posts
When my cog unscrewed...

the chain came off the cog and rattled around between the spokes and the chain stays but didn't lock anything up. I was able to stop the bike in a straight line with the front brake. This is not to say that it's impossible to for the chain to jam the back wheel, just saying that it is not inevitable either. A converted road bike with a 130mm rear axle leaves room for less disastrous results.
 
1 - 9 of 9 Posts
Top