If your 126 mm frame is carbon fiber or held together by glue, you probably shouldn’t try to spread it. That still doesn’t mean that you’re stuck with 7-speeds!
Any 7-speed Shimano Hyperglide Freehub will actually work with 8 sprockets, without any modification! What you need to do is to use 8 of the sprockets from a 9-speed cassette, with the 9-speed spacers.
To make this work, you’ll also need to use a 9-speed chain and shifters. Your old 7-speed derailer should work OK if it isn’t too badly worn. The limit stops on the derailer will cause the useless 9th position on the shifters to be locked out, so this will work as a perfectly normal 8-speed rig.[/quote]
Any of you guys actually done this, or seen it done? I am going to run this on my Black Lightning.
As posted before, I’ve done 7 of 8 on a 7sp freehub. Works great. I did it because I have a CF 126mm spaced frame and I received free 8sp brifters. I just removed 1 cog and 1 spacer (I pulled the 13T on a 12-23 cassette) and the resulting cassette was just the right size for the hyperglide lockring to hold it tight. I actually emailed back and forth with Sheldon about this. It was a while ago.
My old boss at Georges believes you should be able to replace the 7sp freehub body with an 8/9/10 freehub, respace the hub and run a modern set up on there. The clearances on my frame are so tight that I hesitate. The chain on mine barely misses the seat stay when I’m in the smallest cog and I’m worried it’ll be too close with the bigger freehub body. Might be fine for you to do that though zombie.
I’ve heard that some 7 speed Shimano 600 shifters will also index with 8. I have tricolor-era downtube shifters. Anybody know?[/quote]
How? All indexed shifters that I’ve seen come with a set number of clicks built in. I have some 6-speed Shimano 600 indexed downtube shifters on my Miyata that I run in friction mode because I use a 7-speed cassette. It isn’t really necessary, but if I could run them in indexed mode, that would be fun.
Anyways, I think it’s the correct part. My hub might be spaced at 120 right now, actually. I think I’ll have to redish and space it before it I get this bike rolling.
At home now. Definitely the right part. You might be buying a longer axle too, but you can get away with a lot in that regard (see Sheldons story about using an axle that didn’t engage the dropout)
