Crank arms

Not sure what bb he would use…?!

ISIS square taper. :+1:t3:

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Would he get one for a modern tt frame ?

I have a bb question for you, I’ll find all the bits and mail you.

ISIS and Square Taper are two different BB stds. ISIS has (had) multiple splines like the hollowtech.

I really wish the whole BB thing could be sorted out. My preference would be threaded external BBs, and fixed axles as present.

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Ah - yes, so it was :man_facepalming:t4:

See, I’m not some BB nerd :pleading_face:

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I have no idea what you’re all talking about now. Its far too complicated.

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Everything should be like modern Shimano chainsets with external threaded BBs. It just works. There is really no excuse for anything else!

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I think some brands are going back to threaded BB shells?

100% agree.
Those press fit ones are an utter arse and creak like a squirrel.

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Threaded is easy to do at home too, without a Press or faffing about trying to remove them without damaging the frame.

I would really avoid changing BB… there are so many different standards that it’s a minefield. Even bike shops have difficulty, I often change BB for friends, it takes a huge amount of research and even then I still get it wrong.

If you have SRAM (probably GPX, but maybe BB30), go like for like. If it’s a Cervelo, it may need a special SRAM crank with longer axle length.

Shimano is easier than SRAM as fewer versions (they are all 24mm and axles all the same length), SRAM use GPX, BB30 and DUB, and have different Axle lengths for Cervelo

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Was there ever really any need to go from 24mm to 30mm? Could any mortals tell the difference?
All my frames are built for 24mm but I have a 30mm axle in the TT bike as I picked up a P2M Rotor crank fairly cheap. It works OK but limits your choice of bearings and they have to be pretty skinny ones so less robust.
I agree with what’s been said before, I’d go with 24mm threaded every time.

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Dura Ace cranks seem OK for the Pro’s and they are all 24mm.

Just standardise on one diameter, one length and threaded, would make cycle mechanics just a little simpler all round… and no creaking Bottom Brackets

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I had a 30mm axle in threaded frame for a while; used a Rotor BSA90 BB (external) and that avoids the small bearing problem. But you need a threaded frame…

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Yeah, mine’s a threaded frame, standard BSA set-up. I think there are different lengths of axle and mine is the shorter one so can’t use anything bigger than what I’ve got. They are external to the actual frame.
I think this is the one I have: