Is crank bent or the BB?

[aknown]

Hi,
Just got a vintage bike and noticed the crank is bent, or the BB is bent?

Should I try unbending it back or should I find a cheap BB, Crank to replace? if so, what kind of BB and crank should I search for?, tried studying different types of BBs but failed to identify mine, and what I can use to replace.

Thank you.

 

[juvela]

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deformation likely to be either

a) spider of drive side crank arm

or

b) bottom bracket spindle

test

demount drive side crank arm and hold tip of screwdriver (for example) up to end of spindle as you slowly rotate spindle using non-drive crank arm

if spindle does not vary/wobble then problem likely to be spider

spider arms can be "adjusted" with a monkey wrench

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[bikeworkshop]

Cottered cranks can be wonky on the spindle, sometimes caused by poor alignment or size/cut of the cotterpin.
Take it all apart and reassemble it with new cotters.
There are 3 sizes of pin, and the depth of cut can vary too.
Google yourself up to speed or pay someone who's already there.

But cotterpins are cheap!

The chainring/crank is a lot softer than the axle, and can be "realigned" with a length of scaffolding - although we have a special tool for it.

 

[jim haseltine]

Cottered cranks can be wonky on the spindle, sometimes caused by poor alignment or size/cut of the cotterpin.

I'd go with that before anything else. The crank/spindle interface could well have suffered from a badly fitted (ie. loose) pin at some point.

 

[juvela]

I'd go with that before anything else. The crank/spindle interface could well have suffered from a badly fitted (ie. loose) pin at some point.

the wedgebolt in residence on the non-drive side arm exhibits a distinctly caveman look



it may be that fitment of a new matched pair of them may resolve symptom

since bearing cup marked BSC thread wedgebolt diameter is likely to be 9.5mm

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