Old 06-23-10, 06:35 PM
Charles Wahl
Disraeli Gears
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I have a bike with 126 mm rear spacing and SR RD, and originally built it with Suntour Ultra-7. No cog clearance problem, but my stays have a flat on the side facing the cogset, too. Shifted fine, but that was when I used a Sedisport chain. Having replaced that with an SRAM PC 58 or 870 (which I like because it's easy to break the chain for cleaning), it has a sort of “hitch” on the middle cog that bugged me, so I've replaced it with a Suntour 6-speed. Shifting is really good, slightly better than the Ultra-7 I think, and no more hitch. I don't know whether the new FW is Ultra-6, or not, but the spacing of the middle cogs is just slightly larger than on the Ultra-7. I was tempted to try a Wipperman chain on the Ultra-7, but they're more expensive, so maybe some other time.

Largest cog on either FW is 26, and the RD has no problem at all moving smartly onto that, so I'd bet that 28 would be no problem. Of course, upper cog capability also has to do somewhat with the height of the dropout offset, and where, exactly, the axle is WRT the RD mounting hole.
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