Educate me on MTB front derailleurs

[John M]

I am setting up a cross frame as commuter bike for my wife with a MTB triple drivetrain and flat bar. The frame is a Gunnar crosshairs with under BB cable routing. She prefers the SRAM twist type shifters. This will be 9s with a triple front (probably) 44/32/22 crankset.

Too many types of FDs out there!!! What type of FD do we need? I am thinking a top mount, down swing, bottom pull. Is that correct?

Thanks for the help.



(Please don't suggest that a compact double, road triple, drop bar, etc.... would be better for her. It might be, but it isn't what she wants.....She wants a bike that is light and agile like a road bike, but geared low like her MTB).

[Willie1]

Road and MTB FDs have different pull ratios (in 9 speed) so the front shifter will have to be a MTB shifter unless you go to SRAM 10 speed. You can use either SRAM of Shimano, I prefer XT or XTR (Shimano), or XO/XX (SRAM.) I have read the SLX works quite well, but haven't used one myself. Your chainline might be an issue as MTB cranks have a 50mm chainline usually, and road is a few MM less. If she is in the two lower gears usually, then it won't be as much of an issue. You are correct, you will need a top mount, bottom pull FD.

[Loki]

I would get a nine speed LX, SLX XT but they all work about the same as it is a rather crude affair just pushing the chain back and forth. The nicer ones have better pivots so they last longer. Make sure you measure your seat tube because you can use a larger clamp with the rubber insert but can't use a small clamp on a large seat tube. Front derailleurs are one place I am willing to cheap out.