crank problem
09-10-08, 01:53 AM
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crank problem
so i was riding today and my left crank came loose. so i stopped and tightened the nut to make it tight again. but, the black plastic thing that goes around the nut disappeared.
should i replace that black plastic piece or is having it not necessary?
should i replace that black plastic piece or is having it not necessary?
09-10-08, 02:43 AM
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Yeh, that's just to keep dust/dirt out! Coming loose after handtightening isn't a big problem, it takes alot of strain, so this wouldn't suprise me. Make sure to get it properly tightened soon though, had a set of cranks eat apart a bottom bracket from this before, leading to the replacement of both the cranks and BB!
On a similar note, to save myself starting a new thread.. Does anyone know of a way to repair a crank arm if the pedals were over tightened and the thread was eaten apart on the inside where pedal screws into arm?
The previous owner (Ebay) damaged them and instead of struggling to find a similar replacement I'd prefer to repair them if possible. Anyone have any ideas? I've heard about drilling out the original hole, slide in a sleeve with the original thread in the inside, and a new one on the outside to hold that sleeve in place.. I'd be up for trying this if there's no easier way of doing it! Does anyone even know what thread the average pedal is threaded to?
Cheers for any input! Sorry for th hi-jack!
On a similar note, to save myself starting a new thread.. Does anyone know of a way to repair a crank arm if the pedals were over tightened and the thread was eaten apart on the inside where pedal screws into arm?
The previous owner (Ebay) damaged them and instead of struggling to find a similar replacement I'd prefer to repair them if possible. Anyone have any ideas? I've heard about drilling out the original hole, slide in a sleeve with the original thread in the inside, and a new one on the outside to hold that sleeve in place.. I'd be up for trying this if there's no easier way of doing it! Does anyone even know what thread the average pedal is threaded to?
Cheers for any input! Sorry for th hi-jack!
09-10-08, 07:25 AM
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Most pedal threads are 9/16" x 20 tpi threads (also remember you have reverse threading on the left side).
You can re-tap the crank if the threads aren't too chewed. If the threads are toasted you need to retap and use a helicoli insert but unless these are rare or high value cranks its rarely worth it.
From somewhere else on bike forums:
"Helicoil insets are made to repair stripped threads. You thread a metal insert into a slightly larger threaded hole that you make to end up with new threads of the same pitch and diameter of the old stripped threads. If there is a helicoil for the reverse threads on one crank of a bike I don't know. That's usually the side that gets stripped.
The labor is as much as the cost of many crank arms anyway. It's also best done with a drill press, and you need the special helicoil tool, the special ( maybe reverse thread)tap for helicoils and a reverse thread helicoil too. If the crank is not expensive just get a new crank arm, or a used one. If the bike is special or has cottered cranks and they won't come off easily you could ask the bike shop or a machine shop about a helicoil insert. The tools to do the job are as much as the price of the bike, if you don't have them."
You can re-tap the crank if the threads aren't too chewed. If the threads are toasted you need to retap and use a helicoli insert but unless these are rare or high value cranks its rarely worth it.
From somewhere else on bike forums:
"Helicoil insets are made to repair stripped threads. You thread a metal insert into a slightly larger threaded hole that you make to end up with new threads of the same pitch and diameter of the old stripped threads. If there is a helicoil for the reverse threads on one crank of a bike I don't know. That's usually the side that gets stripped.
The labor is as much as the cost of many crank arms anyway. It's also best done with a drill press, and you need the special helicoil tool, the special ( maybe reverse thread)tap for helicoils and a reverse thread helicoil too. If the crank is not expensive just get a new crank arm, or a used one. If the bike is special or has cottered cranks and they won't come off easily you could ask the bike shop or a machine shop about a helicoil insert. The tools to do the job are as much as the price of the bike, if you don't have them."
09-10-08, 07:49 AM
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Jeez, thanks a mill for the very informative post! Hopefully I can source one and solve the problem.. My dad knows people in a few different trades, so maybe they could help!
At the minute, they are kinda precious, only cranks I can find in my budget! (postage is killing me online to Ireland! More than the set is!)
Hopefully I can sort this and get pedalling again, can feel the weight coming back on!
Cheers man!
At the minute, they are kinda precious, only cranks I can find in my budget! (postage is killing me online to Ireland! More than the set is!)
Hopefully I can sort this and get pedalling again, can feel the weight coming back on!
Cheers man!
09-10-08, 07:54 AM
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If it was actually a nut, there was no ring. A bolt? It was a dust cap to protect the crank tool threads. It's not essential to safe operation, but I would get another bolt with the 'cap' when you get the time.
