# My bottom bracket does not fit, is it ok ?



## Trebz (18 Mar 2012)

Hi all

Just bought a new Shimano UN54 for my recently acquired Orange P7.

The bottom bracket shell on the frame is 68mm wide so i bought a 68-73mm bottom bracket.

When the bottom bracket is fitted the left hand side plastic thread cup does not tighten fully up to the frames bottom bracket shell.

Is this ok?


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## fossyant (18 Mar 2012)

Some don't go all the way flush, but I would check the cranks are equal distance from the centre of the BB.

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## I like Skol (18 Mar 2012)

I thought the options were 68 OR 73, not one size fits all? I would suggest if you have a 68mm shell then you need a 68mm BB.


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## lukesdad (18 Mar 2012)

isnt it left side first right side second ?


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## Cubist (18 Mar 2012)

If I remember correctly a 68-73mm BB comes with three spacers, and on a 68 you fit one spacer to the left side, and two spacers to the right side. Have you fitted the spacer on the left side?


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## I like Skol (18 Mar 2012)

When I bought a UN54 BB a couple of months ago the thing I specifically remember (apart from the fact that supplies seem to be drying up?) was that all the sizes where specified by BB shell width of either 68 or 73 and by axle length (eg. 113, 122 etc). I don't recall seeing any that suggested a variable shell width capability.


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## Reluctant (19 Mar 2012)

Skol's right. A UN54 square taper bb comes with no spacers. It needs to be specific to a shell size, ie. 68 OR 73 - not both. Supplies of UN54 are running out, but guess what! There's a UN55 available so nothing to worry about


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## RUSSELL COOPER (26 Sep 2012)

thanks i shall try, and thanks for the link about fitting too!


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## 02GF74 (26 Sep 2012)

lukesdad said:


> isnt it left side first right side second ?


 not the ones i've seen - the RH side cup (in sitting postion facing forwards), has a shoulder so can only be fitted in one positon, the cup is tightened until the shoulder is agaisnt hte bottom brakcet- this is to ensure the chain is in line - the LH side has no shoulder and is sometimes plastic - that is done up until the bearing is snug in the cup.


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