Stripped Square Taper Crank Extraction Threads

[dyna-ti]

Most better dedicated bike shop mechanics who maybe sponsor teams and have been about a bit(not down the docks or anything like that though i do wonder sometimes) and the tool rack to match.
NO and not that either :shock: See how some folks minds work.
Anyway
You know the type of place,and certainly not halfords(though they might help if all else fails with the above puller ^
In amongst your good LBS tool collection with be a puller with a fractionally deeper cut thread designed to reform the thread by cutting its own.

I had a puller start to rip out of a cook bros crank and in the panic that followed had the whole thing down at the 'good' lbs where he employed such a tool.
Problem solved and i was suitably chastised on buying cheap.


A note on pullers

Cheap is not good
Shimano, is i think £17 buts its worth every penny as ive never had theirs pull out, but have with cyclo and a basic £5 model.

 

[Leighcal]

Re: Re:

I've had the same issue. Easily resolved with a small clutch puller, a three armed tool that you should be able to find in and Halfords or B&Q, and you can pop the crank on and off to your heart's content, pulls on the central lump of the crank spider, pushes on the axle. Bob's your uncle.

That's the kind of thing I was on about. Got mine from screwfix think it was 7 quid

 

[mk one]

Hi, just a technique I've used that works even on seemingly seized on crank arms, which is usually why the soft threads strip out of the crank in the first place.
The bb spindle is tapered so all you need to do is lightly tap the crank arm with something soft, I've used rubber mallets, rubber coated screwdriver handles, anything that won't mark the crank arm. The main thing is how light you tap it, which is very!! OK,, a couple of taps on the inside of the arm, then a couple on the outside, as if your trying to tap it back on, repeat s few times and even the most seized crank arm will just fall off!! Works every time, just remember it only needs to be gentle taps to get the arm rocking on the taper

Mark.

 

[Pipmeister]

Re:

Cheers Mark,

This technique hadn’t occurred to me, and I can see how it would work – like wiggling or wobbling it off. I’ve been trying think of an analogy to describe the theory....

As I’ve now refitted the Crank in question by using a Crank Extractor Bolt set-up and some Loctite, I reckon I just might whip a Crank Bolt off another one of my bikes and give it a go.

Pip.