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  1. #1
    mtbr member
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    Jun 2008
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    Chainring changing question

    I currently have a truvativ crankset 22-32-42, with a front derailleur with a 20t capacity, and an 11-34 cassette. I can spin out the high (42-11) gear on level ground (only about 29 mph!) and wish to have the ability to go faster (this is my commuter bike). Can I drop the 22 granny ring, shift the other two rings down, add a 48t chainring and just move the derailleur up and be fine? thus creating a 32-42-48 crankset?

    Thanks in advance for any help in this matter.

  2. #2
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    Reputation: Bikinfoolferlife's Avatar
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    Feb 2004
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    Your rings are dependent on the bolt circle diameter (bcd) on your crank for chainrings and number of bolt holes/arms (5 or 4 generally, mostly 4 these days). Your two largest rings generally share the same bcd, but the granny is smaller, so unlikely you could even get a 32 in the granny bcd and your current 32 won't work at all (unless you have a very odd crankset).

    ps Try visiting here to start http://sheldonbrown.com/gloss_bo-z.html#bcd
    "...the people get the government they deserve..."
    suum quique

  3. #3
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    Thanks. but that raises another question.

    1) is there some kind of longer bolt and spacer combo so that the 32 and 42 ring could share the same hole on the frame facing side of the crank? (if not this is something somebody should really look into!)

    If there isnt such a combo I guess I could buy a 28 and a 38 chainring or just make it a 2 x 9 with the 32-48 chainrings. I dont ever use the 22.

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