Square Taper Cranks

For discussions about bikes and equipment.
mattsccm
Posts: 5101
Joined: 28 Nov 2009, 9:44pm

Re: Square Taper Cranks

Post by mattsccm »

Not that I am a great fan of them, but cotter pins are not as bad as they seem. Left to corrode for decades they can be a pig to remove but if the correct sizes are used they are fine. As for specialist tools..... Well I guess that clever little presses exist but usually a smack with a hammer, with a bit of wood inbetween, works well.
As an ignorant youth I found that the back of a wood splitting maul does the job just fine if they are a touch sticky.
User avatar
531colin
Posts: 16083
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Square Taper Cranks

Post by 531colin »

We don't really know what he is doing?
The picture on previous page shows a lever (socket) attached to a "chainwheel" to drive a freewheel. Is anything attached to the other end of the BB axle?
Cotter pins transfer the drive from the left crank to the (right) chainwheel....you can bludgeon them out on a bicycle, but I don't know where they will be on this device?
If it is just driving the attached chainwheel, then a BB bearing unit is "overkill" ....and if its difficult to work on why do it? square taper and external BBs you can at least dismantle them without resorting to violence. You can't get self-extracting cotter pins any more!

ImageIMG_5141 by 531colin, on Flickr
rogerzilla
Posts: 2887
Joined: 9 Jun 2008, 8:06pm

Re: Square Taper Cranks

Post by rogerzilla »

I find cotter pins come out ok if fitted with anti-seize. However, the usual scenario is trying to remove pins fitted dry by a bike factory 50 years ago, and left to rust in a shed. If you're lucky, you can get one side off and then you only need a BB and *one* new crank to fix the bike.

A cotter press, a bit like a really heavy-duty G-clamp, is the ideal tool but they are rare and/or expensive.
Post Reply