Bicycle Mechanics - MTB shifters with road derailers

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Seattle_Jerry
05-14-09, 01:36 AM
Will rapid fires work on a road bike with dura-ace derailers? I have a 9 speed setup and was thinking as I rode my mountain bike with xtr rapid fire that I like how it shifts better than my road set up. Plus I spend most my time on the upper bars anyway.
Rear pull is the same. front pull is different. That said, you could switch your FD, and off you go..
HillRider
05-14-09, 07:48 AM
The big disqualifier is that MTB shifters won't fit on a road bike's drop bars.
Otherwise, as noted, the rear shifting will be fine as Shimano road and MTB rear derailleurs are interchangable.
The front shifting won't work well and if you fit a MTB front deraileur to the road bike, the cage curvature won't match the larger chainrings. It will work after a fashion but you will have to mount the fd too high and shifting will be poor.
don't forget the brake cable pull is also different.
IK_biker
05-14-09, 10:03 AM
As others pointed out, the cable pull is different. You still may get shifting in the front, but the shifting performance would suffer.
The other thing no one mentioned is the chainline - MTB derailleurs target 48-50 mm, while the road doubles aim at 43.5, and the road triples - at 45 mm. The end result would be a sour front shifting.
This you would not be able to rectify, unless you find a way to offset your cranks.
Yes, there are ways (shim the chainrings on the spider, use BB with a spacer, or adjustable one) depending on what cranks you have.
The gist is, don't do it.
the gist is, don't do it.
+1
Seattle_Jerry
05-14-09, 04:07 PM
I can live with a bar end shifter for the front...I live in a hilly area its mainly all the changes in gear at the rear cluster over rolling hills...so much easier on rapid fire. But then you end up with franken-bike
Shimano makes flat-bar style shifters with levers specifically to use on a road bike. But as others have mentioned, the front derailleur will have to be exchanged for one specific to the shifters. The nice thing is the levers work with the road calipers.
Been there, done that on this particular subject.
making a franken bike is like a rite of passage.
quite fun to mix and match. like campy 10sp shifters to deore SGS RD, which runs 13-34 9sp 105/deore mixed cassette with sugino 26-36-46 triple crankset being shifted by a 105 double FD.
Jeff Wills
05-14-09, 10:34 PM
Shimano makes flat-bar style shifters with levers specifically to use on a road bike. But as others have mentioned, the front derailleur will have to be exchanged for one specific to the shifters. The nice thing is the levers work with the road calipers.
Been there, done that on this particular subject.
The "flat-bar" shifters are identical to the mountain-bike shifters, except for color. As others have noted, the FR-R453 derailleur works with the "MTB" front shifter and larger chainrings. It's a popular setup on recumbents:
http://home.comcast.net/~jeff_wills/jeff-grr/pages/bike022.htm
http://home.comcast.net/~jeff_wills/diane-grr/pages/bike006.htm
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