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Now i have actually put the cranks on, but the old 1990's square taper biopace crank arm went on a bit too easy. I assumed square taper is square taper. Do i need a proper old bottom bracket at all? Or is the standard shimano square bottom bracket fine??
thanks
Errr. Octalink is different to square taper! If it looks like a square hole, it's not octalink.
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This is Octalink.
IIRC all square tapers use the same angle, so they should all work. On some designs the crank will move further up the axle as the tapers are slightly narrower. Have your cranks been used?
oops meant bio pace :oops:. and yes they have been used.. 😳
thanks. they move all the way up the shaft and stop at the crank arms face.
However they is a reasonable amount of taper on the bb not used.
Ah!
Depends what you mean by "too easy." When I have fitted square taper cranks they just push on without much/any resistance, then the crank bolt pulls it all together and pushes the cranks up the axle.
Not sure if this is normal or not. I tried a few lengths and got the cranks to almost touch the shell (for chainline issues), so I can't see if there is 'spare' taper. How far do the tapers run through the crank if you take the bolt out and have a look?a reasonable amount of taper on the bb not used.
thanks a quick google has suggested normal square taper is fine for the bb.
Yes what you say makes perfect sense. Sorry for the confusion. thanks.
EDIT: I was too slow typing the reply an' it's all been covered above. 😉
about 3 - 3.5 mm.
It tighted ok though.
However i needed a 127mm axle length for the rings to clear the frame,
so it may just be the arms are extra long anf thus are still 'square' for longer than more sensibly sized bb's.
Do they only run 2-2.5mm into the crank, or they go through to about 2-2.5mm from the outside edge?
If the former - there's something wrong and there isn't enough supporting the crank. If the latter, sounds perfect.
3.- 3.5mm outside edge. Ie the crank arms still has 3.5 left that doesn't have a shaft going through it. Visable after tightening and then removing the bolt.
thanks for the help.