Specialized Crave SL BB width?

[goobags]

Just replaced my BB due to a failed drive side bearing. Out of curiosity I measured the distance from the inside of each crank to the seat tube and came up with a 5mm difference.

I have a 68/73mm BB so put a spacer in either side which then made the crank bind up. I removed the drive side spacer and the measurement is now even but still seems something isn't quite right.

Anyone else had similar issues? The cranks are a SRAM crank but I don't have much detail on them.


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[creaky]

Just replaced my BB due to a failed drive side bearing. Out of curiosity I measured the distance from the inside of each crank to the seat tube and came up with a 5mm difference.

I have a 68/73mm BB so put a spacer in either side which then made the crank bind up. I removed the drive side spacer and the measurement is now even but still seems something isn't quite right.

Anyone else had similar issues? The cranks are a SRAM crank but I don't have much detail on them.


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Generally get instructions with the BB for each BB shell width. You should measure the BB shell width of the frame before installing to ensure you following the correct instructions for spacers etc.

The seat tubes can be offset to one side for front derailleur clearance etc. so often better to assess whether the cranks are 'central' using the chainstays unless they are a funky design.

 

[The Duckmeister]

Yeah measuring between the crank & seat tube isn't reliable. Measure the bottom bracket shell excluding the bearing cups.

Hollowtech 2/GXP/MegaExo type 2-piece crank & bottom bracket assemblies are designed to allow for both 68 & 73mm shells, plus the fitting of a bottom bracket mounted (E-Type) front derailleur or chain guide; add or delete spacers as appropriate to keep the same overall assembled width.

Standard setups are: 73mm shell with E-Type derailleur/guide - no spacers. 73mm without E-Type derailleur/guide - one spacer on drive side. 68mm shell with E-Type derailleur/guide - one spacer each side. 68mm shell, without E-Type derailleur/guide - two spacers on drive side, one on non-drive side.

 

[goobags]

Should have explained further.

Second hand bike, did have a 68mm shell width which I measured and had no spacers. Put the new BB in and measured the distance from crank to seat tube. I only thought of it as I noticed a few mm gap on the drive side between spider and BB shell

I'll measure again and determine what cranks they are. I'm thinking the old BB was installed incorrectly.


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[goobags]

Derp, should have done more reading. The old BB was installed incorrectly with no spacers making the cranks off centre.

The Crave SL definitely uses a 73mm BB I have now found out. I have one spacer on the non drive side which is the fixed bearing. The drive side won't fit another spacer but the cranks seem centred now from all my measuring.

Thanks for the help anyway


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[hifiandmtb]

You *might* need a wavy washer to take up a millimetre of so of slack.

I needed one on my Stumpy HT.

 

[goobags]

Well now I'm confused.

Measurement from down tube and seat tube are even but chain stays are off centre by one spacer width

How can a seat tube be off centre as stated above? I would have thought a chain stay is more likely to be off centre than the seat tube...

I still reckon I have it set up correct and the previous owner stuffed it up.

By the way it's a GXP crank so the positioning is determined fully by the non drive side bearing


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