Singlespeed & Fixed Gear - Project Bike
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07-16-03, 06:14 AM
I just thought I'd post a pic of my project bike before I get started on it. I'm going to build this bike up as a single speed or fixed gear, I'm not sure which yet.
It has a 6 speed freewheel on it now, is it possible to convert the freewheel into a fixed gear?
Regarding cranks, I assume you use a standard double crank and leave the outer ring off?
(sorry if these questions have been asked and answered before, I guess I'd better go read through the previous posts).
07-16-03, 07:50 AM
You can use the existing crank, just use the inner cr and get some bmx cr bolts.
I would take the freewheel off and then put a track cog on with a bb lockring and locktite. I have never done this but many very informative people from this forum swear by this.
Most of these questions and more are archived at this site.
I have been looking for a frame with a 650 front wheel for a fixed project. I would go fixed and not ss. with a frame like that but good luck with whatever you decide.
07-16-03, 07:54 AM
Have you read Sheldon Brown's articles on fixed gear? There have been some more or less successful modifications of freewheels to fixed by welding the pawls or something. I'm not sure why anyone would want to go to the trouble. What you can do is take off the freewheel, screw on your track cog, then use a standard bottom bracket lockring to lock it down. A number of people use this setup successfully, but it has to be done carefully. A real fixed gear hub has standard clockwise threads for threading on the cog then outer counter-clockwise (left hand) threading for a track lockring. When slowing down a fixie by resisting the forward motion of the cranks you put tremendous "backward" or counter-clockwise stress on the cog. A left hand track lockring prevents the cog from unscrewing because this backward stress actually tends to tighten the lockring. When using on bb lockring on standard freewheel threads, there must be VERY good lockup to prevent the whole setup from unthreading. This does not mean screwing both cog and lockring down as tightly as possible, but screwing the cog on good and tight then the lockring then tightening the two against each other. Sorry if this is embarassingly elementary since this is how all lockrings and locknuts work, but I'm never sure if everyone quite understands this concept since one can often get away with simply tightening the first cup or nut down tight then tightening down the locknut/ring. I sometimes wonder if this is why some people seem to have trouble with headsets, hubs, or bb's regularly getting out of adjustment. On these parts the problem is just one of adjustment. Failure to achieve a good lockup on a fixed gear can result an a sudden unthreading of lockring and cog - not a good thing.
With regard to cranks, yes, you can just use one ring on a double crank, but you need to get a set of short stack crank bolts because regular crank bolts will be too long when you remove a ring.
Hope this helps,
07-16-03, 08:10 AM
Couple of thoughts: bigger wheel on the front, shorter cranks. These both allow for more pedal clearance as you have to pedal around corners.
07-16-03, 10:16 PM
Is that a GT, old schooly? Freakish...
Not sure a larger diameter tire can go up front. Check out that headtube angle
07-17-03, 01:21 AM
it looks like it's either a nishiki or a shogun TT bike with a 24 inch front wheel and not a 650. putting a larger front wheel on would seriously hurt the steering. assuming that the front wheel and fork are what was originally on the frame, any normal sized crank should be fine as the frame builder most likely accounted for the smaller front wheel (note that the head tube angle looks to be at about the same angle as a normal road bike).
Zack, do yourself a favor and get a real track hub if you're going to go fixed on it. i did the cog/bb lockring thing for a while and it worked, but i also was running front and rear brakes the whole time and was using a 52:16 ratio. needless to say, i wasn't leg-locking. of you decide to run brakes, be careful you don't flip the bike over by grabbing the front too hard. and maybe go for riser bars and maybe a different if you plan on riding that for more than a few hours at a time. that bike looks pretty sick, by the way, and pursuits are fun to ride.
07-17-03, 02:51 AM
Good point 165, I wasn't looking closely enough. Chain-stay angle also points to a fairly high BB. I'd still put 165mm cranks on for fixed street riding.
07-17-03, 06:08 AM
Guys, thanks for all of the great info you've provided. The bike is a Nishiki TT bike from the mid 80's running 700c on the rear and 24" up front. I saw a link for a single speed shop in NYC that seems to have all of the bits and pieces I'd need to make the conversion.
As far as the amount of time I'd ride it, I don't think I'd ride it more than an hour or two at the most. Probably my first purchase will be a flip flop rear wheel. I'm going to strip and repaint the frame before building it up.
I'll keep you all posted on my progress.
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