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I want to use my front derailleur which is a tiagra on a 3x10 speed setup with a compact double crankset making it a 2x10 setup.

What is the proper procedure for setting up the triple chainring front derailleur as a 2x10 setup compared to setting up a standard double chainring setup? Will I be able to use limit screws to set limits properly for top and bottom ranges?

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I didn't think that was possible. Aren't the chainrings closer together in a triple? –  amcnabb Mar 25 '13 at 22:41
    
I could be wrong, but doesn't a triple require a different/longer bottom bracket too? –  PeteH Mar 25 '13 at 23:08
    
Mainly it's a question of how far apart the cogs are on the double vs the triple. If the spacing is similar, it should be a simple matter of picking one ring to be the "middle", then adjusting the limit for the other ring. You may or may not then be able to adjust the other limit to keep the chain from jumping off. If not, you need to kluge some way to stop the motion (maybe a longer limit screw). Probably best to make the outer ring the "middle" and the inner one still the inner. –  Daniel R Hicks Mar 26 '13 at 0:46
    
I did this with a 105 setup that was manufactured circa 2006. All I had to do was swap out the crankset, tighten up the "low" limiter screw so that it wouldn't shift onto the now non-existent small ring, and adjust the cables. Everything worked like a dream.I'm not sure if that would still hold true with stuff that's manufactured for 10 speed. –  jimirings Mar 26 '13 at 13:12

1 Answer 1

As with many things bike related, it might not meet the specs, but that doesn't mean that it won't work.

Some questions that will help answer the question:

  • Are you using friction or index shifting for the front? If friction (such as bar-end shifters) you should be fine. If indexed, you might have incompatibilities with cable pull, especially if you're trying to use the same shifters or switching between a road vs. MTB derailleur.
  • Do the limit screws allow adjustment to the range of motion that you require? If so, you might be OK, but it really depends on the number of teeth on your derailleur.

If you happen to already have the parts and have worked on bikes a bit in the past "just try it" usually works for me. You might be pleasantly surprised. If you have to buy the parts or pay for labor it might not be worth the trouble.

Far more information on the topic can be found here:

http://sheldonbrown.com/front-derailers.html

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