Re: [CR]cottered cranks question

Date: Fri, 09 Feb 2001 14:42:38 +0000
Subject: Re: [CR]cottered cranks question
From: Bob Reid <>
To: <>
In-Reply-To: <>

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 cotter
> pin goes through the 'correct' ammount on the spider side and only needs a
> 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 file
> the more chance you have of altering the angle of the 'flat' and therefore
> 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 do
>> shouldn't mean running the risk of stripping the threads. I say shouldn't
>> -
>> but this of course is dependant on just how hard and what's used to tighten
>> the nut. I got taught at college, that torque wrenches were just a more
>> 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 tubes
>> involved), but this was for "standard" bolts where they were designed for a
>> specific clamping load tightened by "standard" spanners - and then there
>> were cotter pins, cycle threads and tools (engineering on a budget) and a
>> virtual thread war between B.S.A. and Raleigh.
>> When your faced with a cheap cotterless crank wedged onto the BB axle and
>> with no threads left for the extractor to grip on - you might just remember
>> 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 case
>> 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 the
>> 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