I have managed to break the crank on my mountain bike, I have an old bike which I can cannibalise for parts, however, I have been unable to get to the large (40mm) crank nut on the gear side of the bike, due to the fact that there is very narrow access, & any adjustable spanner, that I have tried is simply too wide to fit into the gap. Basically, I need a narrow 40mm spanner, any ideas where I can get one. ( I have tried a few so called cycling shops, to no avail) . Can I then simply extract the crank or does it need some persuasion with a hammer! Cheers.
I have managed to break the crank on my mountain bike, I have an old bike which I can cannibalise for parts, however, I have been unable to get to the large (40mm) crank nut on the gear side of the bike, due to the fact that there is very narrow access, & any adjustable spanner, that I have tried is simply too wide to fit into the gap. Basically, I need a narrow 40mm spanner, any ideas where I can get one. ( I have tried a few so called cycling shops, to no avail) . Can I then simply extract the crank or does it need some persuasion with a hammer! Cheers.
I I have been unable to get to the large (40mm) crank nut on the gear side of the bike, due to the fact that there is very narrow access, & any adjustable spanner, that I have tried is simply too wide to fit into the gap. Basically, I need a narrow 40mm spanner, any ideas where I can get one. ( I have tried a few so called cycling shops, to no avail) . Can I then simply extract the crank or does it need some persuasion with a hammer! Cheers.
Dave
Don't use a hammer, you'll destroy the seating of the crank on the bottom bracket spindle. Get the appropriate crank extracting tool. When you remove the left cup, remember that it's reverse threaded.
Don't use a hammer, you'll destroy the seating of the crank on the bottom bracket spindle. Get the appropriate crank extracting tool. When you remove the left cup, remember that it's reverse threaded.
Thanks oldbobcat, I'll use some restraint! but any ideas on obtaining the appropriate spanner?
Thanks oldbobcat, I'll use some restraint! but any ideas on obtaining the appropriate spanner?
Difficult for me to say, because I don't know what brand or style of cranks you're working with. Some brand and model names, and/or a photo of your problem, would be helpful.
You could get a cheap(say secondhand) spanner that is the correct size but too fat to fit and grind it down with say an angle grinder. I've done that for a pedal spanner as all the usual spanners(except for relatively expensive bicycle only ones) are too fat to fit safely.
When I worked at the LBS, I used one of these, carefully mind you, it can slip off if the BB cup is too tight. It's a headset spanner with a 40mm end to it. You can probably find a cheaper one from another manufacturer as it's a standard headset wrench.
If you want to reuse the axle, you're just going to have to pull the crankarm off sooner or later. You may find a narrow 40mm wrench somewhere but I think pulling the crankarm off is the preferred method, plus a puller is likely cheaper than buying a special wrench. It's really the simplest thing you ever saw: the outer part threads into the crank arm and the inner bolt pushes against the axle. $10, tops.
Unless you have cottered cranks in which case it's even cheaper to pull them off.
If your MTB has a one-piece crank, the way to go is to take the non-drive-side pedal and bearing cone off and pull the crank out to the drive side.
