hi friends,
i’m working on getting my old commuter rideable again, & the main issue with it is a skipping crankshaft that has slowly
gotten worse, assumedly from more & more stripping on the drivetrain (could be using the wrong names here). i looked around & couldn’t find anyone with a similar issue.
i wanted to take it off & see inside, but some bozo at my LBS drove a pin through the shaft years ago to “fix” the problem, & now i simply cannot pull this pin out. (pictured in comments).
any ideas on how y’all would approach this? is pulling that pin out the only way to see inside? hopes & prayers appreciated, thank you xoxo
by dmorr84
3 Comments
https://preview.redd.it/3fg14yhzb8kc1.jpeg?width=3024&format=pjpg&auto=webp&s=bca1b70f6de7415182299f53b05c981af7ca6029
pin picture, as promised !
The “pin” is a cotter, and is supposed to be there, to keep the crankarm attached to the bottom bracket axle. It looks as though yours is loose, allowing the non-drive-side crankarm to rotate a few degrees on the axle. This is, granted, obsolete technology, but it can be fixed. If you can’t get the cotter out (and often, they are stuck), you’ll need to drill it out. A drill press is best, if you have access to one, but I’ve done it with an electric hand drill. Use a metal-specific bit, low RPM, oil, and do it in stages to avoid overheating.
See: https://www.restoration.bike/bike-repair/cottered-crank-removal/
Sourcing replacement cotters is getting harder all the time, but you can find them on Amazon (sorry).
hey bozo
that pin is supposed to be there. Its called a cotter pin and is basically a wedge with a nut on the end.
They are made of a soft metal to stop your crank and bottom bracket axle from wearing out.
and are pretty much a disposable item although they can last a long time and not come loose.
If they are ridden when loose they can wear a groove in the middle making it difficult to remove, so a bit of persuasion with a hammer or maybe a drill will get it off, make sure not to hit the axle
[https://bikeraceinfo.com/images-all/tech-images/bottom-bracket/Cotter-Cranks.jpg](https://bikeraceinfo.com/images-all/tech-images/bottom-bracket/Cotter-Cranks.jpg)
see how the axle is cut half away to make room for the wedge of the cotter pin to fit through
there are a few styles of cotter pins but yours looks reasonably default
some times to get a new cotterpin to fit nicely we have to file the angle of the wedge a little
and then fit with force like a hammer, sometimes people use a block of hard wood to stop the top getting deformed (and this useful for removal as we don’t want to bend the thread for the nut )
once this wedged cotterpin is fitted its best not to ride it when loose as it can quickly get worn (like all cranks, they don’t like being ridden when loose)
sometimes if caught early enough one can remove them and file a little so the wedge is straight again but yours seems unlikely. If to much of the wedge is filed away then it will enter the hole too far making a poor fit.
on the plus side they are reasonably cheap to buy but a bit of an old school thing these days as they haven’t been used on many bikes since at least the 80’s
[https://www.ebay.co.uk/itm/386614422904?chn=ps&_ul=GB&_trkparms=ispr%3D1&amdata=enc%3A18zqacQVlSK6zzyQzsMUzCg8&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&mkscid=101&itemid=386614422904&targetid=1647205088560&device=c&mktype=pla&googleloc=1006812&poi=1006565&campaignid=19926849521&mkgroupid=147378848803&rlsatarget=pla-1647205088560&abcId=9311021&merchantid=6995734&gad_source=4&gclid=CjwKCAiA_tuuBhAUEiwAvxkgTq65x6VOOwi9pdEmKcaYbbrtfr9uQGyqrr2CKOloNgKhbK1vNlubShoC_C4QAvD_BwE](https://www.ebay.co.uk/itm/386614422904?chn=ps&_ul=GB&_trkparms=ispr%3D1&amdata=enc%3A18zqacQVlSK6zzyQzsMUzCg8&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&mkscid=101&itemid=386614422904&targetid=1647205088560&device=c&mktype=pla&googleloc=1006812&poi=1006565&campaignid=19926849521&mkgroupid=147378848803&rlsatarget=pla-1647205088560&abcId=9311021&merchantid=6995734&gad_source=4&gclid=CjwKCAiA_tuuBhAUEiwAvxkgTq65x6VOOwi9pdEmKcaYbbrtfr9uQGyqrr2CKOloNgKhbK1vNlubShoC_C4QAvD_BwE)