I should have a new frame arriving for my 12 year old soon. Cranks are going to be a bit of a pain though as he has 152s at the moment which fit him well, but they're square taper.Â
Old frame is non boost, 68mm shell, new one is boost, 73mm.
How the hell am I supposed to work out what size bb it needs? Is it a case of try to find markings on the current one, and adding 11mm to the axle length? (the bb difference, plus the boost difference)
I bloody hate square taper. I'm half tempted to just stick on the 165 XTs I've got and tell him to grow quicker m
I put square taper cranks on my elder daughter’s bike to reduce the crank length cheaply and that’s boost. HUP Racing told me to get the 123mm version of the 73mm BSA English UN300 Shimano JIS square taper BB, and it does indeed fit.
Is it a case of try to find markings on the current one, and adding 11mm to the axle length?
Well you don't need to find markings, just measure the length of the axle.Â
I put square taper cranks on my elder daughter’s bike to reduce the crank length cheaply and that’s boost. HUP Racing told me to get the 123mm version of the 73mm BSA English UN300 Shimano JIS square taper BB, and it does indeed fit.
Nice one, cheers dude! That's super helpful. That's kind of what I thought.Â
Well you don't need to find markings, just measure the length of the axle.Â
Good point, that'll work as well! 😀
Â
Â