No road ahead for lower gears

No road ahead for lower gears

I have been asked to lower the gears on someone’s road bike and bought a 12-36 cassette with a Deore SLX shadow rear mech. The shifters are 105 (10-speed). It doesn’t seem to be pulling enough cable through. Have they changed the ratio for Shadow?

David Beacham

It sounds like you mistakenly bought a 10-speed MTB rear mech. The pull ratio on that is different, not because it’s a Shadow mech, but because it’s MTB 10-speed, which paradoxically is the last thing you want with 10-speed road shifters. Shimano calls this new pull ratio Dyna-Sys. It’s not compatible with anything else that they or anyone makes, so it completes the separation of road from mountain.

What you need is a 9-speed MTB mech of as good quality as you can still get hold of, so it’ll be precisely made enough to shift within the finer tolerances of 10-speed. And since your friend wants a bottom sprocket bigger than 34, it’ll need to be the Shadow design.

Once all the 2011 equipment sells out, it will become true that Shadow means a different pull ratio, since there aren’t any 9-speed Shadow mechs in the 2012 catalogue. This will also be pain for anyone who bought a 29er MTB more than one year ago, since a broken mech means they won’t be able to get really low gears without replacing everything with 10-speed Dyna-Sys.

Chris Juden

 

This was first published in the June / July 2012 edition of CTC's Cycle magazine.

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