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Hope someone can help

I'm converting a hybrid frame to a gravel/adventure bike and am using the GRX 1x11 rx600 cranks. I've got myself a BBR60 Ultegra bottom bracket but the left-hand (non-drive side) crank arm hits my bike frame as it rotates. The amount it clips it by is 1 or 2 mm at most, so very annoying!

Question is can you get spacers for this bottom bracket, or would it be worth returning it and getting another one?

Thanks

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    How wide is the bottom bracket shell?
    – Paul H
    Feb 1, 2021 at 16:07
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    Hi, welcome to bicycles! Please note that in any question about fit, a photo of the problem is a great help when making suggestions.
    – DavidW
    Feb 1, 2021 at 18:33
  • What's the frame? Is it a newer frame sized for a BB386EVO? If so there's no way to make the BBR60 fit.
    – DavidW
    Feb 1, 2021 at 20:53

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If it's a steel frame, then adding indentation on the left side is a solution, albeit an advanced one that needs to be done with care. A good way to do it at home is use a piece of wood and a rasp/file to create a support form for the inside of the chainstay, tape that to one vise jaw, tape a socket lengthwise to the other vise jaw, and squish. The way they do it at factories is not particularly any more sophisticated. A good rule of thumb type minimum gap to avoid rub under load is 3mm, so in other words you're doing 2mm to eliminate the interference and then another 3 to accomodate flex. Measure the frame OLD beforehand and then if it changes, align the frame afterward with a 2x4 and string. Standard caution that yes you can destroy the bike doing this kind of thing.

If it's not a steel frame there is no solution.

There are no spacer tricks you can play with Shimano road cranks because you can't compromise the left side spline engagement by any amount, and certainly not by the amount you would need here to both eliminate the interference and then create the aforementioned gap. Not safe, risks ruining the cranks and/or having the arm fall off etc. The BB is intended to use without any spacers, so there is no swapping or adding spacers to offset it. (In other words, yes you could create clearance by adding spacers under the left side cup or on the spindle itself, but there will be inadequate contact surface between the spindle and the crank with any such solution.)

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  • Thanks for your reply. It's an aluminium frame with a 68mm bottom bracket shell. In terms of shimano bottom brackets not using spacers, I've seen the mountain bike MT800 bottom bracket comes with spacers, so was thinking along the lines of using spacers as this does. If not, could I just use the MT800 bottom bracket to push the bb cups out slightly as it is only a small amount needed.
    – moosernator1
    Feb 2, 2021 at 17:29
  • @moosenator1 bicycles.stackexchange.com/questions/47334/… . If you took away the plastic shield and installed mountain cups with 2mm of spacer on the left and and none on the right, that is a way of buying 1mm additional clearance at the expense of making the BB much more contamination prone and screwing up your chainline and the symmetry of your cranks, and still won't give you clearance for flex.
    – Nathan Knutson
    Feb 2, 2021 at 18:22
  • @moosenator1 The GRX cranks are nice but not if they wear a hole in your chainstay. It really sounds like you should return/resell them and just get a mountain crank.
    – Nathan Knutson
    Feb 2, 2021 at 18:27

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