Re: [CR]cottered cranks question

Example: Racing:Roger de Vlaeminck

From: "John Swarbrick" <>
Subject: Re: [CR]cottered cranks question
Date: Mon, 12 Feb 2001 13:46:04 -0000

Fellow listees,

I followed the advice from Bob at the weekend RE filing the Cotters.

I must say it worked a treat.

This is what i did.

i bought some more cotters giving me about 6 in total. I then selectively assembled them on to the axle with the cranks finding which were the best fit for each crank. 1 cotter fitted the spider side perfectly without any filing allowing for 1 thread showing beyond the nut when fitted with the nut and washer.

The other cotter needed some judicious filing I clamped a 1.5" wide bastard file to my 'work bench' and ran the cotter back and forth along it (i don't own a vice (vise)). i taped up my fingers with masking tape to avoid problems there. i used magic marker on the flat to guage how well the cotter fitted and where the point of contact was with the axle i used numerous dry fitting sessions to get the cotter fitting perfectly.

after i fitted the axle into the bottom bracket i lightly greased the axle flat as well as the cotter to help it into position.

I then 'drew' up the nut after I put a little thread locker onto the threads.

Fitted the rings back to the crank adjusted the simplex rod changer.

I did 50 miles on the bike yesterday the cranks are perfect. I guess that there are many ways of fitting cotter pins to cranks I followed Bobs method and it worked very well.


>From: Bob Reid <>
>To: <>
>Subject: Re: [CR]cottered cranks question
>Date: Fri, 09 Feb 2001 14:42:38 +0000
>I'd say you are right about the difference being between the cranks and BB
>axle if both pins end up with the same result though it does seem strange .
>There are two ways to resolve it - try a different English cotter pin (not
>all so-called "standard" cotters are equal) or better still file down the
>one you have - it's surprising just how little metal you need to remove to
>gain quite a few threads more. I was taught to file them all (except
>sometimes those fitted to axles with worn flats) to get the nut fully one
>thread past the end of the pin - another reason why some people manage to
>strip the threads off !
>Bob Reid
> > From: "John Swarbrick" <>
> > Date: Fri, 09 Feb 2001 13:59:30 -0000
> > To:,
> > Subject: Re: [CR]cottered cranks question
> >
> > Hi Bob,
> >
> > I have a cottered crank fitting session coming up soon.
> > I'm using Durax cranks with a Baylis Whiley BB with english cotters
> > My problem is that when I 'dry fit' the axle and cranks together. The
> > pin goes through the 'correct' ammount on the spider side and only needs
> > bit of filing for a perfect fit. However on the LH crank
> > the pin barely goes through at all, with only a bit of the thread
>showing at
> > the end. This is going to take lots more filing. I guess the more you
> > the more chance you have of altering the angle of the 'flat' and
> > the cranks won't be 180' apart.
> >
> > Is this normal or do I need to get some other cotter pins.
> > swaping the pins I have around makes no differance. I'm guessing the
> > differance lies in the BB axle or crank.
> >
> >
> > Your right you can 'feel' quite accurately with a spanner.
> > Cheers,
> >
> > John.
> >
> >
> >> From: Bob Reid <>
> >> To: <>
> >> Subject: Re: [CR]cottered cranks question
> >> Date: Fri, 09 Feb 2001 13:08:18 +0000
> >>
> >> If you get the 'fit' right first the amount of "drawing-on" you have to
> >> shouldn't mean running the risk of stripping the threads. I say
> >> -
> >> but this of course is dependant on just how hard and what's used to
> >> the nut. I got taught at college, that torque wrenches were just a
> >> accurate spanner - spanners then being uniformly of a length that the
> >> "average" man would tighten it properly and yet not exceed the elastic
> >> limit
> >> of the bolt/nut combination when applied correctly (i.e. no bars or
> >> involved), but this was for "standard" bolts where they were designed
>for a
> >> specific clamping load tightened by "standard" spanners - and then
> >> were cotter pins, cycle threads and tools (engineering on a budget) and
> >> virtual thread war between B.S.A. and Raleigh.
> >>
> >> When your faced with a cheap cotterless crank wedged onto the BB axle
> >> with no threads left for the extractor to grip on - you might just
> >> how easy most cotter pins were to come out if done correctly.
> >>
> >> p.s. I still have not came across "standard-man" (though we do have
> >> law
> >> who says who he is - the man on the Clapham Omnibus)
> >>
> >> :-)
> >>
> >> best regards
> >>
> >> Bob Reid
> >> Stonehaven
> >> Scotland
> >>
> >>
> >>
> >>
> >>
> >>
> >>> From:
> >>> Date: Fri, 9 Feb 2001 06:58:25 EST
> >>> To:,
> >>> Subject: Re: [CR]cottered cranks question
> >>>
> >>> I don't see anything wrong with fine tuning the fit with a file, on
> >> other
> >>> hand I thought you weren't supposed to draw the pin tight with the nut
> >>> because of danger of stripping the threads on the pin and/or nut.
> >>>
> >>>
> >>> Pete Geurds
> >>> Douglassville, Pa