Sram Force Double FD vs. Shimano Triple Crank = Trouble?
08-30-10, 11:09 PM
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Sram Force Double FD vs. Shimano Triple Crank = Trouble?
I'm installing a Sram Force fd with a 16 tooth max differential, along with a Shimano 105 hollowtech triple crank (52-42-30). Shifting is being accomplished with bar ends. If I interpreted it correctly, Shelden Brown's article stated that if I use friction shifting, I can use a double designated fd with a triple ring crank? My concern is the 16 tooth max is being exceeded; should I scrap the force and look for a fd with a 22 tooth diff.capacity?
08-30-10, 11:14 PM
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If you've already got the parts, it doesn't hurt to try.
08-31-10, 02:54 PM
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The biggest problem will probably be in shifting from the middle to the small - triple FDs have the cage shaped to knock the chain off of the middle ring, double FDs donŽt. Therefore, youŽll need to set it up to allow the FD to move in further than you might otherwise allow it to, so that the outer plate moves in far enough to knock the chain off the middle ring. Unfortunately, this will mean that the inner plate is further in that you would normally allow it to be, which, couple with the fact that the inner plate doesnŽt extend down very far, makes it extra likely that youŽll derail the chain. Shifts from the small to the middle also wonŽt be overly smooth, but should be doable given the use of a friction shifter.
As said above, give it a try, but donŽt be surprised if the middle-to-small shift is a bit of a problem.
As said above, give it a try, but donŽt be surprised if the middle-to-small shift is a bit of a problem.
08-31-10, 04:05 PM
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It will work but it won't be ideal. I recommend adding a Third Eye chain Watcher, N-Gear Jump Stop or similar to the bike to keep the chain from dropping off the inside of the granny ring. That way you can set your front derailleur's low limit screw to allow a solid middle-to-granny shift without worrying that the chain will spill to the inside.
