Hello,

I’ve been helping a neighbour with his his bike.. he has a v basic bike from the equivalent of halfords here…

He has a square taper BB which was goosed..he replaced it with a shimano cartridge unit (same dimensions exatcly) and now the chainline is shot..

i dont understand i must admit – never had that happen..?

What do you think?

How did you measure the BB, that was “goosed”?

The length of the spindle/axle doesn’t always equate to the stated size of a BB. Found this with Shimano BB’s.

there are also at least 2 “standards” for the dimensions of the taper, maybe he/you got unlucky if the previous one wasn’t shimano

Not an “E” type is it?

If the old BB/crank was ISO and replaced with a JIS of similar dimensions, the ‘fatter’ taper of the JIS BB would push the crank/chainline 4.5mm out.

ah ok, many variables.

I measured the length of the spindle on the one that was going out, as i have always done.. then measured the frame and thought it’d be good…

its not an old bike, just a cheapo one.

Going to have a remesure and see.

I measured the length of the spindle on the one that was going out

The size should be marked on the old BB.

yes thanks it was but we measured just incase! Its a cheapo bike and was semi printed on the bb.. but not v clear.

in all my years of mtbing and biking in general ive never had this issue..

sorted it now. all is good. ta singletrack

what was wrong ?