Cotter pin ruined

I've given the BB a clean and regrease on my girlfriend's bike.
when mounting the cranks, I must have inserted the pins the wrong way round and now the axle has made a big indentation in the tapered side of the pin.

So, my girlfriend enquired at a shop on Lamb's Conduct Street, they gave her a replacement pin, which almost fits. I could file it down carfully, but I'm worried about it's quality. it's much more lightweight than the original and has a smaller nut which has too ample tolerance for my liking.

So first question:
Does the poorer quality of the new pin matter?
Second question:
If it does, where can I find a proper replacement?
Third question:
Do I just get her new square taper BB and crankset?

Cheers,
Cedric

cotters pins these days are mainly poor quality because cottered cranks are only used on the cheapest of cheap new bikes. if you're concerned about quality and longevity, upgrade the crankset to square taper...

Cheers, I guess I'll to go this route then

A lot of cotter pins need filing, it's normal. But there's also two sizes of cotter pins, metric and imperial - British bikes use imperial, except Raleigh which use (something close to) metric. How does it compare to the old one?

I've used cheap cotter pins on my beater and on my girlfriend's bike with no problems. They're supposed to be slightly soft so that they conform to the shape of the axle and give a good snug fit, otherwise they'd click. Just make sure you install them properly:

Support under cotter pin with a big pipe
Grease pin copiously
Hammer in pin
Tighten nut (lightly! Don't strip the threads!)
Hammer in again
Tighten nut
Ride for a day
Hammer in again
Tighten nut
Repeat until you can't hammer it in any further.

The worst than can happen is that it keeps coming loose, in which case you can get cottered cranks anyway.

ok, I'll give it a go. Crosses fingers, the stakes are high, no failure tolerated on this one :O

ok, I'll give it a go. Crosses fingers, the stakes are high, no failure tolerated on this one :O

Can it - there is a better way. You know you've always wanted an arc welder.

I damaged a cotter pin a few months ago and LMNH replaced and fitted a new one for me for next to nothing. They had both sizes in stock at the time. Definitely recommended.

I went to LMNH today actually and got 2 sizes to try out, their quality is way better than the previous one I got. So I'm very happy with that, I just need to fit it on now.
Yeah, £1 per cotter pin (non fitted), great value!
Thanks everyone, should be ok now but I'll update the thread if anything new comes up!

Bigtwin: I do have an arc welder back in France haha, indeed, I could fill the old one and re-use it. But the good idea has been over-ridden I'm afraid.