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Thread: New Crank Set ?

  1. #1
    Senior Member KDC1956's Avatar
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    New Crank Set ?

    How hard is it to install a new crank set.I have a surly lht and it has the 48-36-26t on it.I have got a Shimano M442 170mm
    22-32-44t crank set to replace it with my LBS said this will fit and work with it.I work on a lot of bicycle but this will be my first time to replace this kind of crank set so I would like to know how hard this will be.I have the tools to take it off with and if needed I can get a new BB for it too.I ask my LBS and they said it should work with the one it has on it now.If not I can buy a new one for 25.00.Thanks any input on this will be nice.
    Last edited by KDC1956; 11-17-09 at 02:53 AM.

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    Pretty easy, unless the cranks are very hard to pull. Normally they come off with the puller, as easily as cranking on a nut or bolt with a socket. My most recent pair would not come off period, no obvious sign of problems, greased when installed. Normally it is pretty simple. So you just pull them off and then clean the taper, lightly grease, and install the new ones. Seems they commonly come loose after about 500 miles, and need to be reset, then they seem to last for ever. That's my experience, but I have only done it on half dozen bikes. I'm sure there are lots of tips and tricks

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    Senior Member Doug64's Avatar
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    You may have to get a bottom bracket with a shorter spindleto maintain the same chainline.

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    Quote Originally Posted by Doug64 View Post
    You may have to get a bottom bracket with a shorter spindleto maintain the same chainline.
    And you may need to lower the height of the front derailleur to maintain shifting performance. Additionally, it's likely that the chainline will change somewhat, so you'll probably need to adjust the derailleur limit screws. I needed to do all three (fiddle with chainline, FD height, limit screws) when I swapped from a road (53/39/30) to a trekking (48/36/26) triple crank.

  5. #5
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    The issues are:

    1. Bottom bracket. The one recommended for your BB shell width should be OK, but be aware that there are (a) chainline issues and (b) Q issues.

    2. Derailleur. Yes, adjust down, and you might find, depending on the BB spindle width, that you will be at the absolute limit of the derailleur cages outward movement.

    3. Q or tread. MTB cranks are shaped so they are further away from the seat tube than road cranks. This is to accommodate the wider chainstays of MTBs. You will (a) need to decide if you like the wider foot placement when you ride (b) and need to be aware that this can alter your biomechanics such that you can strain knee ligaments until you are used to it.

    I have a Fuji Touring that came with road triple cranks, and I swapped them out for square taper 22-32-44 MTB cranks. I had to fiddle with the BB to get the Q or tread equal on both sides for the BB I was using. The original Tiagra triple derailleur was kept and remains on there, but as I mentioned in (2) above, it was near its outer limit when shifting to the large ring.

    I have now replaced that 22-32-44 with the 26-36-48 Deore MTB crankset. The derailleur is the same, but the BB was the Octalink version, and the standard MTB spindle width for my BB shell has produced a good chainline and not extended the derailleur so much.
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