This forum seems like a logical place for this question - since I assume people here know how to make and alter things very well. If I'm out of place here - sorry about that ..
I'd like to retrofit an old road bike with a fixed-gear flywheel (in place of the rear wheel ) to use as an indoor trainer. Most of the commercial indoor cycles I've seen have anywhere from a 32 to a 60 pound fylwheel. I'll set up some means of resistance - most probably large felt pads actuated by a brake caliper. Has anyone ever done something similar to this? If so - what advice can you provide? Where can one get a suitable flywheel that allows attachment of a fixed gear and lock-ring? I plan to either use an existing rear-wheel-type trainer to support this bike - or possibly consruct a support frame from the readily-available extruded-aluminum industrial-erector-set type sections available.