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Mod Cranks And Bb's.


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I have a 2003 or so echo team mod that I am trying to build up. I have lead on some onza square taper cranks which I want to run FFW on. What size BB do I need in order to do this? I currently have a 118mm square taper BB, is this long enough?

Will a 17t up front and a 13t in the rear work?

Thank you.

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17:13 would be pretty spinny - the usual ratio to run is 18:12, which is the sort of 'optimum' mod gear ratio. As for the BB, you'll almost certainly need a 68x128mm BB (Or a 73x128mm BB, as long as you run the little spacer with it), as anything shorter generally won't work, especially iwth square taper cranks. Just make sure you don't over-tighten the crank bolts as that can stretch the tapers on the cranks, meaning you have to slide them further up the taper to get them to get tight, resulting in less freewheel clearance.

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I don't think it makes a great deal of difference to the drive-side crank, 'cos the majority of BBs come in 73 with the 2.5mm spacer to reduce it to 68mm. As a result, the length of spindle you get on the right-side is the same, it's just the whole unit shifts over 2.5mm. At least, that's what it was like with all the Shimano, FSA and Truvativ BBs I had :)

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