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  1. #1
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    Parts compatibility for CX bike

    i'm piecing together a cyclocross/commuter bike and i had a few questions since i have limited experience with road bike parts.

    can i use an 8 speed sti shifters (dura ace/ult/105) with an 8 speed xt rear derailleur/ (11-28) cassette and a ritchey cyclocross crank (36/46 dbl)?

    looking to end up with an 8 speed/dbl disk brake setup. i'm big and 9 speed chains seem to stretch/wear very quickly under me, whereas i had no problem at all with my old 8 speed xt bike.
    Thanks,
    Mike

  2. #2
    Senior Member sydney's Avatar
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    The 8 speed DA shifters have a unique pull.Don't use them with the XT RD. You sure that cross crank will take a 36 ring? The ritchey cross cranks are typically 130 BCD and the small ring would be a 38.

  3. #3
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    Also, be careful with the front derailer - only shimano road derailers are designed to work properly with STI.

    MTB derailers have a different geometry and therefore move the cage a different amount (for a similar length of cable pull) as an MTB changer.

    So, when you get a front derailer, check with Shimano that it is STI compatible, and designed for smaller chainrings (as road cranksets traditionally have larger rings).

    You can get MTB derailers to work "relatively" well with STI and MTB cranksets, but if you are not committed to a particular front derailer - contact Shimano and they will tell you the best derailer to use.

    Persoanlly, there is a lot of mucking around to get it working - spend the $20 and get a derailer designed to work with STI and smaller chainrings!
    Riding a bike is not a fashion show

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  4. #4
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    Quote Originally Posted by Bike_13
    Also, be careful with the front derailer - only shimano road derailers are designed to work properly with STI.
    That's correct. MTB front derailleurs won't index properly with STI shifters.

    So, when you get a front derailer, check with Shimano that it is STI compatible, and designed for smaller chainrings (as road cranksets traditionally have larger rings).
    Shimano 8-speed road triple front derailleurs are pretty tolerant of smaller chainrings than the 52T they were specifically designed for. My son had a Trek that came with a 7-speed RSX group that had 46/36/26T chainrings but an RX-100 FD intended for a 52/42/30T road crank. It shifted fine.

  5. #5
    Senior Member sydney's Avatar
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    Quote Originally Posted by Bike_13
    Also, be careful with the front derailer - only shimano road derailers are designed to work properly with STI.

    MTB derailers have a different geometry and therefore move the cage a different amount (for a similar length of cable pull) as an MTB changer.

    So, when you get a front derailer, check with Shimano that it is STI compatible, and designed for smaller chainrings (as road cranksets traditionally have larger rings).

    You can get MTB derailers to work "relatively" well with STI and MTB cranksets, but if you are not committed to a particular front derailer - contact Shimano and they will tell you the best derailer to use.

    Persoanlly, there is a lot of mucking around to get it working - spend the $20 and get a derailer designed to work with STI and smaller chainrings!
    So, you've got a line on a shimano STI compatible road FD specific for a 46 ring?? The only choice is a reqular road FD,and I've used a 9 speed 105 and it worked fine.

  6. #6
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    I just set up a cross bike with 8 speed STI (600) shifters and an 8 speed XTR rear derailleur. Up-shifts require a bigger push on the lever--I haven't spend any time adjusting it yet--but it's completely tolerable. The indexing is fine. If you've got the parts, I'd throw them on and see if it works.

  7. #7
    Senior Member sydney's Avatar
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    The rear isn't an issue.

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