Hey Jeff, thanks for the information. I'm guessing the frame is 120mm OLD since it had a 5-speed freewheel as original equipment. I can't measure it right now since it's hooked up to the xtracycle free radical. A 126mm hub might squeeze in there or the frame could be tweaked a little, but if I'm going to go to 126mm, and I have to re-space and re-dish I might as well get a 7-speed hyperglide freewheel at that point. Do you think I'm right in thinking that the 6-speed SiS XT thumbie I have would index that with the "phantom" click?
Thanks for the link to the IRD site, those look like nice units with hyperglide style ramps. A little spendy but if it's my only outlay to do this upgrade not too bad. Hey look what they say about stack height - 5-spd: 29.2mm, 6-spd: 31.5mm, 7-spd: 34.1mm
That 6-spd is pretty close to the 5-spd, so I'm guessing it's using the tighter 7-spd cog spacing? If that 2mm is the only additional width, I'm sure that would squeeze into my drop-outs and no worries about re-dishing. And it would probably work with my 6-speed XT thumbie?
Guess there's only one way to find out.
BTW I have the old wheel from the bike the XT thumbies came off, so I thought about using it, but the cogs are pretty worn and finding 6-speed Uniglide cassettes seems difficult these days. Also the hub bearings sound and feel horrible so I'm afraid the races may be shot. And I kinda want to keep the original rear wheel from the bike going as it matches the front and is in good condition. (even though it would have a non-original rear deraileur and thumb shifter).