Bicycle Mechanics - FD compatibility

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View Full Version : FD compatibility


hybridbkrdr
08-21-11, 07:28 AM
From the research that I've done, it looks like a front derailleur I wanted to try on an 8 speed setup with a 48T large chainring, was actually designed for a maximum 46T chainring and for 7 speeds.

So, does anyone think there would be any problem using a 46T max. 7 speed front derailleur on an 8 speed setup with a 48T max. crankset?


FBinNY
08-21-11, 07:55 AM
Shouldn't be a problem at all. Watch the cage height, depending on seat tube angle it may be closer near the bottom than the top so you won't be able to get it as low.

hybridbkrdr
08-21-11, 01:40 PM
Cool, thanks. I'm not sure if I completely understand the second phrase but I'll see I guess.


FBinNY
08-21-11, 01:53 PM
Cool, thanks. I'm not sure if I completely understand the second phrase but I'll see I guess.

I'm sorry. Normally the closest point of contact between the FD and chainrings is at the top of the chainring, but with chainrings bigger than what the FD is designed around, the curvature is different and the back, or lowest part of the cage is closer.

If you set the height at the top without checking the back, it might jam on the chainring.

dscheidt
08-21-11, 03:16 PM
Also, watch the inside plate of the derailleur doesn't hit the middle ring. I've seen a number of mountain derailleurs that wouldn't shift a bigger set of rings than their claimed capacity because that hit.