B***** cotter pins!

[Midlife]

Point the crank arm forwards then line up the flats and press the cotter pin in. Spin the crank so it's pointing backwards and screw on the nut. Do both sides the same and the cotter pins will be "opposites". And not snag on your 70's flares .

Shaun

 

[Uncle Monty]

Success! Well, sort of.....

As Shaun says, drive side at three o'clock, put the pin in thread side down, tap it through and fit the nut and washer. Turn bike round and repeat for the non drive side crank. I tightened the nut, gave them a few more taps, then re tightened. Once I have the bike together I will ride them round the block a few times before checking and tightening them again. The plain end is very long, so I may remove them and machine them down a little.

 

[retrotrack]

I have a question, what was the point in cotter pins? Surely at the time of brazing frames, producing gears, technology was far enough to make a square taper bb?

 

[Uncle Monty]

They were an abomination deliberately invented to torment me....

 

[keithglos]

I have a question, what was the point in cotter pins? Surely at the time of brazing frames, producing gears, technology was far enough to make a square taper bb?

We didn't trust alloy cranks till about 1955. Steel square tapers tended to work loose. Cotter pins were never much of a problem, and were intended to allow for inacurate manufacturing.
Keith

 

[Midlife]

Cottered cranks were actually quite elegant in the end..... Chater Lea did some hollow cranks which were really quite light for their day

My brain has died at this time of night ( time for bed matron) but there was a sort of half taper-half cottered crank with the axle having a sort of triangular shape..........that never caught on either LOL

Now this is going to annoy me............

Shaun

 

[Jonny69]

Well cottered cranks from the factory actually worked pretty well. I've had a couple of bikes now with either their original cotter pins or very old replaced ones and, really, until I've had to take them out for whatever reason, they've never worked loose. As soon as you put new ones in, which are very soft in comparison and have cut threads which shear off easily, you start to run into problems. Once I'd worked out what the problem was, I now try my best to preserve the old pins if at all possible and re-use them. You can often hammer old ones out and not even damage the screw thread; new ones just mash up.

 

[keithglos]

Cottered cranks were actually quite elegant in the end..... Chater Lea did some hollow cranks which were really quite light for their day

My brain has died at this time of night ( time for bed matron) but there was a sort of half taper-half cottered crank with the axle having a sort of triangular shape..........that never caught on either LOL

Now this is going to annoy me............

Shaun

I think you mean TA
Keith

 

[Elysarian]

I always used to run into problems getting the buggers out (to service/replace crank bearings) - I always bought a new pair before attempting to do anything BB-related...

Fitting new ones was kinda therapeutic for me, filing the flats until they fitted just so then drop in, tap and tighten etc. (as other posters have stated).

Kids these days don't know they're born with their Hollowtech2 (and other easy to take apart) gear

 

[Iwasgoodonce]

Just to help me, can someone post a picture of a perfectly fitted cotter pin? I think I might have to file a bit off as only half the threaded bit is sticking out the other side.

Thanks.