fixed gear freewheel conversion
Got an old Atala 960'S or 70's) bike with 3 bolt crankset, Regina Corsa SICC 2 prong 5 speed freewheel on Super Iris wheel with the dimpled brake surface. I've read Sheldon's piece on conversion but still a bit confused. Particularly with the using the original rear hub part.
Not sure if this is the forum or I should go to the mechanics forum but will try here first.
Once the freewheel is removed (if at all possible), I can thread on a fixed sprocket. I have to adjust the existing spacers (on either side of the wheel on the axle?) to eyeball the chain line. Then re-dish the wheel.
The questions are:
Do I need to buy additional spacers and washers to supplement what's already on the wheel?
If more spacers are needed, what diameter should they be, do they go between the sprocket and the wheel or outside the sprocket?
Do I have to buy the fixed sprocket to thread on or it can be taken off the Regina freewheel or some other freewheel?
If the sprockets have to be purchased, does it matter whether it's left or right hand thread?
The English BB lock ring is the last thing before the dropouts?
Quick release can be used on the rear wheel?
Last edited by cyclingd; 08-31-10 at 03:51 PM.
You cannot turn your old multi geared freeweel hub into a fixed gear, you need a fixed gear specific hub.
You could turn it into a singlespeed by threading on a single speed freewheel rather than the 6? speed freewheel you are going to take off.
Per Sheldon Brown:
The cheapest way to convert a multi-speed bicycle into a fixed gear is to use the original rear hub, assuming that it is made for a conventional threaded freewheel. A fixed sprocket will thread right on, but there is no provision for a left threaded lock ring.
So I thought it would be possible - just the instructions weren't too clear.
Yes it is possible. You just have to make sure it's on tight! I find rotafixing works very well: http://en.wikipedia.org/wiki/Rotafix
Once you get your freewheel removed (your LBS can do this if you don't have the proper tool) you can just thread on the cog of your choice. If your chainline is not straight, you will need to rearrange the spacers on your axle. You seemed a little confused on the whole sprocket/spacer thing so I'll try and explain that. Your axle is separate and doesn't have anything to do with your freewheel/cog. Once you remove your freewheel you'll see this. The axle has spacers on it that can be moved around. Once you move them around to get your chainline correct you will have to have a bike shop re-dish your wheel so it's still centered in the frame.
So to answer your questions:
1. No, you don't need additional spacers (unless you can't rearrange them enough to straighten your chain.)
2. Any washer that fits around your axle will work fine. They don't need to be bike specific.
3. Buying a track cog is the easiest way to go. Make sure it has the correct teeth for the chain you'll be using! It must be right-hand threaded.
4. Your hub probably won't have enough threads for the lock ring. But if it does, it will need the same threading as your cog.
Yes, it is possible -- just search on "suicide hub" on these fora.
Originally Posted by cyclingd
That said, and as Sheldon notes, there is no provision for a lockring on a standard freewheel hub. This means that using your legs as brakes -- skidding, for example -- will tend to unscrew the cog from the hub. Once this happens you lose the ability to brake with your legs, which can be worrisome in an urgent situation.
If you decide to install a track cog onto your freewheel hub, avoid using your legs to brake and install at least a front caliper brake (preferably front *AND* rear) as well to control your speed. Otherwise you're asking for trouble.
Or just buy/ build a proper rear wheel and do it safely rather than trying to rig something together that may or may not work.
There's nothing rigged up about it. If you're doing it on a budget, run both brakes and it'll be just as safe as a new wheel with a lockring.