Bicycle Mechanics - Crank Extraction When They're Ain't no Threads
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I had a problem with cranks(1980 Campy BMX) that had no threads. Most mechanics use ball joint remover. It works but may cause unnecessary damage. The way around this is to purchase a tie-rod puller for about $12. The jaws fit behind you cranks while the screw pushes against the bottom bracket spindle(I used a small metal cylinder to keep the spindle threads from getting damaged. Works like a charm with no damage to crank arms or spindle
12-26-04, 07:27 PM
The ball joint puller is a very good idea, but I would substitute a bolt for the 'metal cylinder'. A threaded in bolt is a lot stronger.
If that Idea doesnt work(which it should) I have had last ditch succes with heat. That is if it is an aluminum arm. Heat makes the aluminum expand at a much higher rate than the steel, so it just takes a tap from a blunt force like a wood wedge ot in worst case a punch and hammer. The catch of that method is it eliminates any temper on the arm, thus the arm will be weakened so its a one time only trick.
12-26-04, 08:08 PM
Any wonder why Campy's BMX stuff didn't sell too good?
12-30-04, 12:06 PM
I got a frame with only one crank. The other had been removed, but the NDS extractor threads were stripped. I used it for hanging the frame while I painted it and then built it up save for that last arm.
Remove the crank bolt/nut and go out and torque the hell out of it. I REALLY had to push and alternate with loving taps from a claw hammer. It finally loosened up. Be warned that it may very well round out the spindle hole, so it's a last-ditch-never-wanna-use-this-again technique.
On the other hand, my mtb cranks loosen up all on their own, even after I torque down the nuts.
Many shops can tap threads in the crank or even retap a larger diameter thread if the original threads have been stripped or crossthreaded.
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