Swapping crankset from triple to double compact on Giant TCR

jp1970
jp1970 Posts: 134
edited September 2015 in Workshop
Planning to swap out the crankset on my Giant TCR (2012) from a shimano 105 5700 triple to ultegra 6700 compact. ( shifters and FD will also be changed to match )

Will I be able to do a simple swap with the crankset without having to replace/change the bottom bracket .. I think it's a BB86.

I presume I won't have any chainline issues?

Thanks in advance....

Comments

  • dj58
    dj58 Posts: 2,217
    Should be a straight swop as spec. says your bike has a Shimano pressfit BB. BTW the compact version of that Ultegra crankset is FC-6750. The triple crankset uses a spacers to adjust the chainline, were as the double does not. It is explained in the Shiamo tech.doc SI-1LJ0A-002 and on this page http://si.shimano.com/#seriesList/38/51
  • keef66
    keef66 Posts: 13,123
    I have 2 bikes, one with a Shimano pressfit BB86 BB and the other with BS 68mm screw in HT2 BB. I've regularly swapped between a 5703 triple, 4500 double and a CX50 double chainset without disturbing the BBs on either bike. Just a plastic spacer on each side with the triple (and the drive side one tends to stay hidden behind the spider / stuck on the axle unless you forcibly remove it)

    If you've not removed one before:

    Undo the 2 pinch bolts before attempting to unscrew the plastic preload cap

    If you've not installed one before:

    Lightly grease the axle before inserting it. Then whack the chainset with the flat of your hand to make sure it's all the way through.
    Grease the splines and fit the NDS crank
    Install the plastic preload cap and tighten only finger tight using the little plastic tool
    Then install the lightly greased pinch bolts with their washers and the little plastic safety tab in the gap in the crank. Tighten them alternately until snug / to recommended torque if using a torque wrench.

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