HELP!!! I'm pretty new to being my own mechanic here, but I have so many awesome older bikes and I just want to start using them or making them usable for someone else. This drivetrain isn't widely discussed on how-to sites and I was wondering if anyone has dealt with this situation before... feel free to IM me too if you're into that AIM: annieknowby

They will not make a fixey,the cogs are not really fixed and will turn with good pressure.

With the freewheel in the bottom bracket, I don't see how this could work as a fixie. At least not as easily as replacing with a standard BB, which I've done.

The rear hub is not solidly fixed, as frameteam2003 has said.

HELP!!! I'm pretty new to being my own mechanic here, but I have so many awesome older bikes and I just want to start using them or making them usable for someone else. This drivetrain isn't widely discussed on how-to sites and I was wondering if anyone has dealt with this situation before... feel free to IM me too if you're into that AIM: annieknowby

I was a shop mehanic for 10 years and am a certified fixed gear addict as well as a fan of the late Sheldon Brown, so I like to make things like 160-speed bikes and tall-offroad-track-tandems and hence feel qualified to answer your question:
The other fellow was correct in that FF systems have a "safety" feature that allows the cogset to freewheel if your shoelaces or pantsleg gets caught in the chainrings. I have welded freewheels on to make multispeed fixies, but don't like backlash , as the whole beauty of fixedgear is the precise control you have in traffic--besides, its hell on the rear derailleur.
There are many better ways to have multispeed capability with a fixed gear.

The best thing you an do for a Shimano FF bike is to wrap all your Shimano Positron(Positrash) derailleur parts around it, add all the Shimano RapidRise (viagra competition?) derailleurs you an find, weld on a few dozen pounds of BioPace chainrings and throw the whol offensive mess as far as you can into very, very deep saltwater or an active volcano. Many a mechanic will thank you.

on that note, I have an entire ff system in a box downstairs that I haven't brought myself to throw out yet.
Anyone want it?

...kind of.

http://www.bikeforums.net/attachment.php?attachmentid=80642&stc=1&d=1220989274