Is there some sort of trick to installing 3 piece cranks? I have a single speed Beach cruiser with 3 piece cranks , I bought it in March and am on my third left crank . I don't know whether or not it is something am doing wrong riding or not . i broke the original left pedal and replaced the set. Then my left crank kept loosening up and wallowed out to the point that I had to replace so I put on another steel left crank and repacked and adjusted the bottom bracket. the new left crank loosened and wobbled to the point of eventual failure so I upgraded to a complete new Shrum alloy crankset with a 46 t sprocket and repleaced the bottom bracket with a sealed cartridge unit. That left crank began to fail just the same way so I put on yet another alloy left crank which loosened and fell off on a long ride . As of now I have reinstalled this crank and am limping on it until crank number 4 arrives in the mail . They have all been 170mm cranks and I have tried torquing them on with an impact wrench as well as loctite on the threads . any suggestions?
Crank spindles
- Thread starter onex29er
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that's a lot of bad luck... :x
i believe left crankarms are the reason bike shops started offering "30 day adjustments", etc...
spindle and arm should be free of grease (just a wipe with a rag is fine). grease the threads of the crank nut or bolt and the flange where it contacts the crankarm so it's free to turn and tighten without 'digging in' to the arm. don't know much about impact wrenches, but you should have a hard time overtightening it with a conventional crank bolt wrench. if it's an allen, maybe a short cheater bar...check it after each of your next couple rides....good luck! :wink:
i believe left crankarms are the reason bike shops started offering "30 day adjustments", etc...
spindle and arm should be free of grease (just a wipe with a rag is fine). grease the threads of the crank nut or bolt and the flange where it contacts the crankarm so it's free to turn and tighten without 'digging in' to the arm. don't know much about impact wrenches, but you should have a hard time overtightening it with a conventional crank bolt wrench. if it's an allen, maybe a short cheater bar...check it after each of your next couple rides....good luck! :wink:
it sounds like you are using a square taper bottom bracket, either there is something wrong with that side of the bottom bracket or you arent tightening the crank on enough. Square tapered cranks need to be tightened on to the point where the tapers bottom out as the crank is being pressed onto the bottom bracket. you should need a crank removal tool to press them back off or it is not on tight enough. you can put a little grease or anti seize on the taper to aid in them being pressed together.
I don't know the cause of the initial issue, but it's a Wal Mart bike so I'll bet it wasn't installed correctly. It also sounds like you are pretty hard on them which is fine, but you just have to be aware that after a ride you're going to have to check your crank bolts. If you are torquing them with an impact wrench you are over-tightening the crank arm and opening up the spindle slot (square hole). No amount of tightening can undo that damage. You may have also damged the spindle of your sealed BB, but that's less likely.
When you get the new crank, grease the spindle, grease the bolt. Install it. Tighten it down hard, but don't use any breaker bars, impact wrenches or anything like that. Just tighten it down hard by hand. After you ride it, check for tightness. If it becomes a problem again, it may be your cranks aren't built for your level of use. If you are breaking pedals you may be taking jumps and such which means you may need strength in your bike that a $200 Chinese Wal Mart beast isn't going to provide.
When you get the new crank, grease the spindle, grease the bolt. Install it. Tighten it down hard, but don't use any breaker bars, impact wrenches or anything like that. Just tighten it down hard by hand. After you ride it, check for tightness. If it becomes a problem again, it may be your cranks aren't built for your level of use. If you are breaking pedals you may be taking jumps and such which means you may need strength in your bike that a $200 Chinese Wal Mart beast isn't going to provide.
The age old argument of whether greasing the spindle is needed.
http://janheine.wordpress.com/2012/04/1 ... to-grease/
http://en.wikipedia.org/wiki/Bottom_bra ... red_cranks
http://janheine.wordpress.com/2012/04/1 ... to-grease/
http://en.wikipedia.org/wiki/Bottom_bra ... red_cranks
Was it made for a three piece crankset, or is it in an adapter? A one-piece crankset wouldn't do that. Good luck.
I really don't understand, if you've replaced the bottom bracket also? Weird.
What is loosening? The bolt that holds the crank onto the spindle? The compression of the aluminium crank and the teeth on the back of the bolt head should act as a lock washer and keep that bolt from backing out.
Very strange. Good luck.
I really don't understand, if you've replaced the bottom bracket also? Weird.
What is loosening? The bolt that holds the crank onto the spindle? The compression of the aluminium crank and the teeth on the back of the bolt head should act as a lock washer and keep that bolt from backing out.
Very strange. Good luck.
