I'm sure this has been asked before, but is it possible to convert a stock single-speed (like a cruiser or bmx) to fixed gear, without rebuilding the rear wheel around a new hub? Something you can add or remove to make it not spin?

Thanks.

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It is highly ill advised to mess about trying to convert a FW hub to a FG, this is known as a "Suicide Hub" for good reasons. Using a Track-style hub w/ the FG cog prevented from backing off by the reverse thread lockring is the only safe set-up. Proper FG rear wheels are inexpensive, and impressively so compared to massive dental re-construction or a stay in the ICU.

-Bandera

That's a front wheel.

You can use a bottom bracket lockring on a hub. It works as long as you keep in mind it is right hand threaded just like the cog. If you try to skid, you will probably unscrew both and be in "neutral". Don't do this if you plan to ride brake-less! My first fix gear wheel was a standard 5-speed freewheel wheel with the cog and the BB lockring screwed on. It worked well enough that when I tried to coast, I got shot into the air and dumped unceremoniously on the road. Bike was fine. I never did unscrew that cog and rode that wheel several years. But I always had and used brakes. Skidding to stop was a foreign concept then. We rode fix gears for 1) winter training and 2) winter riding because they were superior in snow, not for showing off.

If you have a single speed wheel, check that you have enough threads for both the cog and the lockring before you do this. I never tried that, just went straight from the road 5-speed freewheel hub to a fix gear hub

Ben

You most definitely can. Application is key though. If you're Jonny from Jonny Cycles and can rip a skid over 200 feet then I wouldn't recommend it. But for every day use, with occasional skip stops and skids, it's ok. I have built many many conversions over the years spinning on a fixed cog without concern. Mind, I clean/degrease/alcohol/acetone the threads of both* very well, use Red Loc-Tite and either Rotafix or use a very long handle(d) chainwhip.** If folks tell you it can't be done safely they are dead wrong. I have had grocery bikes, commuters, fixed MTN bikes, fixed trainers, etc. all with spun on fixed cogs and never had a problem. The first one that ever broke loose was one that my 200 pound skidding brother cracked free after over 2 years of hard use. BTW, when we race up at the track, you can take a gander and see how many of the P/1/2's have lockrings on our rear wheels. You'd be surprised at the lack of them. In over 12 years of racing, I've never seen a problem. Money is hard to come by these days. Forget the new fixed rear wheel/hub. Save some green and buy your Mom/Dad/Dog/Cat/Iguana/Girlfriend/Boyfriend/Spiritual Advisor/Grandma*** a nice Holiday gift.




*hub and cog
**with proper pipe strength of course
***grandpa's have a tendency to hoard, so pass that one up