In this article I’m going to dive into all the mistakes I’ve made with cottered crank removals so you don’t have to. If there’s one area of bike restorations that instills fear into me and get me waking up in the middle of the night screaming it’s bottom brackets. But at a very firm second place is cottered cranks and all of the mistakes I’ve made working with those weak little cotter pins.
Video tutorial
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Rookie mistake 1: Believing your local bike shop will use a cottered crank removal tool
I was very anxious to be removing the cotter pin with all the horror stories I’ve read on the internet. That’s why I thought it would be a good thing to go to my LBS and let the pros do the job. They did, but not with a cottered crank removal tool or cotter pin press, but with a hammer. And much less gently than I probably would have done. I was fortunate enough the pins weren’t all that stuck.
Rookie mistake 2: Believing you need a cottered crank removal tool to get the cotter pin out
No you don’t, you’d be in trouble if you did because cottered crank removal tools are almost impossible to find nowadays. If you really want to have this specialty tool you can still find new cotter pin presses but they’re expensive. Another perfectly legit way of getting a cotter pin out of the way is by using either a vice or clamp.
Rookie mistake 3: Not supporting the crank when using a hammer to get the cotter pin out
Not many people will have a cotter pin press. Park Tool had one, but it has long been discontinued, and the ones you can still find on Ebay are very costly. So the next best thing, apart from making your own cotter pin press or using a vice or clamp is to use a hammer. But if you do make sure to support the crank arm, preferably with a block or wood or something. If you don’t you run the risk of bending the bottom bracket spindle or damaging the bearings and ruining your bottom bracket in the process.
Rookie mistake 4: Hammering directly onto the threads of the cotter pin
If you decide to use a hammer on the cotter pin, use it on a loosened nut, not the threads of the cotter pin. The cotter pin is made of soft metal, probably to prevent it from damaging the crank arms. In fact the metal is so soft, using a hammer to get it loosened can easily turn it into a mushroom instead. And if that happens you can go and try to drill it out. So after loosening the nut, turn it back on until it’s just a millimeter away from the crank arm. The nut will help prevent the cotter pin from mushrooming.
Rookie mistake 5: Hammering directly onto the cotter pin without using a block of wood
Even when the nut is on, don’t directly hammer onto it, but use a block of wood in between the nut and the hammer. Hammers are made of extremely hard steel. A block of wood is not. The nut will most likely damage the wood before the wood has a change to do the same to the nut.
Rookie mistake 6: Believing the cotter pin has to go in a certain way
No it doesn’t matter which way the cotter pin goes in. I’ve read the rule “When the pedal goes down, the cotter goes up.” in an article about cotter pins. But the only thing you need to keep in mind is that the cotter pins are in opposite directions from each other. The aforementioned rule does help you achieve this.
Rookie mistake 7: Tightening a cotter pin using the nut
I’ve done this and ruined the threads on the cotter pin. The metal is way too soft to get the cotter pin tight enough, so I stripped the threads while the crank still had play. Make sure the crank doesn’t have any play. Use a cotter pin press, vice, clamp or hammer. But whatever tool you choose, don’t use the nut.
Rookie mistake 8: Not re-tightening the cotter pins after a couple of miles
If there will be play in the crank arms after you thought you tightened them, it’s probably going to happen in the first few miles you ride on the bike. So make sure there’s no play after you’ve ridden a couple of miles.
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