Problem with new BB

cyclosteve
cyclosteve Posts: 150
edited December 2015 in Workshop
Hi all. here goes I have changed my chainset on my cyclocross bike as it was a 19mm spline and the bb are silly money £30 I get through 3 a year so decided to change to shimano 105 chainset and bb when I fitted the chainset it does not go all the way through its not flush when pushed through it falls about 3mm on offside crank arm I have used the tool to tighten. but if I fit the m/bike bb it goes all way through right to end and when I use the tool to tighten it goes flush like it should. Is it ok to use m/bike bb or the 105 bb with the 3mm difference. The problem is the outside part of the bearings. M/bike measures 10.4 r/bike measures 11.6 can I get away with that 3mm

Comments

  • sungod
    sungod Posts: 17,496
    some punctuation or spacing of sentences would help :)

    sounds like you may have the wrong parts

    measure the width of the bb shell, road is typically 68mm, mtb 73mm, but there are others

    then check the specification of the parts that you have
    my bike - faster than god's and twice as shiny
  • arlowood
    arlowood Posts: 2,561
    You may be experiencing a common problem with fitting new Shimano chainsets to new bearings. It is widely known that the chainset spindle may need some extra persuasion to push through those final few mms to get a snug fit against the bearings.

    Check the driveside of the spindle and see if there is still a tiny gap between the chainset and the outer surface of the BB bearing cup. If so then you may need to adopt the rubber/wooden mallet approach to get it to seat fully.

    Have a read at this recent thread where similar problems were discussed.

    viewtopic.php?f=40004&t=13040793

    Also make sure everything is well greased beforehand

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