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Hi all
I've been doing a lockdown project where I'm trying to build a decent hardtail purely out of 2nd hand parts. I've got most of the parts now including a Cannondale Beast of the East 3 frame of ebay for less than 50 quid. I've not had a Cannondale before and was naive to how annoying they can be with their headsets / bottom brackets etc etc.
Current issue. The frame is one of these ai ones where the drivetrain is supposed to be offset 6mm to the right to give clearance then I think you have to dish the wheel back 6mm to the non drive side. The bottom bracket is BB30 but 83mm wide (it may even be a BB30 83ai). This is annoying as any review I have read said BB30 so I assumed it was 73mm wide before I bought. I have old 3x shimano and 2x truvativ cranksets I was hoping to convert to 1x and use. These cranks are both 24mm and I believe only meant for 73mm BB. I bought a 73mm praxis works BB30 to 24 convertor off ebay so I could use these cranks.
Questions:
- Is there any chance of the praxis works 73mm convertor fitting and having enough thread to be secure if the BB frame is 83mm?
- If the praxis works fits are the 24 mm cranksets not going to be wide enough?
- If none of these work what do I do?! The frame already has BB30 bearings in place held in with the circlips. Do I just need to try and find an 83mm crankset with 30mm width and then worry about the whole ai business later?? The bike when it was sold seemed to come with a Cannondale Si ai crankset with a 30T single ring...not so easy to find.
Any help / ideas would be grateful
Dan
Your best bet might be using the BB30 bearings and having a pair of assymetric 24mm converter bushes made to compensate for the offset - similar to regular BB30 to 24mm adaptors and just use a regular crank like HT2
Many thanks for your input dovebiker. Do you mean try get something custom made? So I would want a bushing the same thickness as the BBS3O bearing, it would sit inside and would reduce the internal diameter down to 24 on one side and 22 on the other?
https://wheelsmfg.com/bb30-adapter-for-shimano-24mm-cranks.html
Like this, but because they need to be 2 different widths to compensate for the 6mm offset and the 83mm shell width. If using a GXP crank, NDS would be 22mm ID. Material like glass-filled nylon or acetal should be fine.
Check the praxis adapter will fit, some (well, mine) Cannondale frames have a step part way through the shell that not much will get through.
Off the top of my head though, is 83mm actually "wide", that sounds fairly standard (there's a BB86 and BB92 which are based on the shimano 68/73mm cranks).
I think cannondale and Race Face share the same spline system, so if you can figure out the right combination raceface cinch cranks should fit if you buy the correct axle and spacers.
That's a fair point about the bb86 bb92. I was just reading some forums about standard hollowtech 2 cranksets for 73mm not being long enough for 83mm frames. I wonder if the 86 and 92 are still narrower than the 83 with external cups which takes make it much wider. I cant remember if the 83 and 92 have external cups as well or not.
I was hoping to not have to think about buying a specific 30mm spindle crank for an 83mm frame as they seem few and far between and quite expensive..this was supposed to be a cheapo build!
if the BB shell is 83mm and BB30, to work with a MTB shimano chainset you need to make it 92mm wide overall.
this is done with press in adapters, that press in to the BB30 bearings and space out to the right diameter and width.
If your BB is symmetrical, https://qwertycycles.co.uk/collections/bottom-brackets/products/fsa-bb30-pf30-to-24mm-bottom-bracket-200-3203 will most likely work, as you only have to make up 9mm (4.5mm each side)
I think with an 83mm BB30 it'll not be the weird BB30A type, thaht was a 68mm shell.
However, speak to Qwertycycles first if you don't know.