On Friday, 13 August 2021 at 5:19:50 am UTC+10 Matthew P wrote: > Ignoring Sram because I am unfamiliar, and a road vs. mtb/mtn difference, > lets say within Shimano mtb/mtn freehub bodies and cassettes, the widths > are the same 8 speed through 12 speed. Double check me here: > https://www.sheldonbrown.com/speeds.html So a rear derailer has to travel > the same distance inboard-outboard-wise for 8-12 speeds, staying within the > confines of friction shifting.
Actually, no. The Shimano MTB freehub body ramains the same width, but from 11s onwards the cassette is 1.85mm wider - the largest cog on a 11-speed MTB cassette overhangs on the inside so that it can fit on the shorter body. So the derailleur has to be able to travel that extra 1.85mm sideways to shift across an 11s cassette. Shimano 11s road hubs have a freehub body with splines that are 1.85mm longer than their 11-speed MTB hubs - because the smaller largest cog on most road cassettes doesn't allow the cassette to overhang on the inside without the derailleur fouling the spokes in the smallest gear. The exception on their 11s road cassettes are the HG-800 and HG-700 11-34 cassettes, where the largest cog is big enough that it can overhang ok, so those cassettes will fit on an 8/9/10 freehub. Not that the extra throw required causes a problem in real life. I've used a Deore XT 7s RD on a 9s cassette, and 9/10s RDs with 11s cassettes, and they've had no problem shifting across the entire cassette. And on the SRAM side, it's their 10s MTB derailleurs (usually labelled "Exact Actuation") that are compatible with their 11s road shifters, if you want to run 11s indexed on a drop bar bike with a wide range cassette. Nick -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/81e5c35a-513f-4785-87d4-4382de8bc95cn%40googlegroups.com.
