Last updated on August 15, 2009
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Tonight I went to pull the crankset off my bike so I could change the chainring bolts and this happened. That bottom flat piece of metal is supposed to be a taller cap, known as the crank puller cap (see crankset instructions here). It sits on the outside of the crank bolt, and as one undoes the crankset bolt it pushes against the cap, which pulls the drive-side crank off. Instead of doing that it just came apart, breaking off at the first ring of threads. This is not supposed to happen. Not much force was needed to break the part and the splines of the crank were well greased when I reassembled everything a few weeks ago, so I figure the cap simply failed.
While I can get another cap, there is a relatively thin cylindrical threaded piece of aluminum stuck in the crankset. I’m not completely sure how to get it out. I also can’t wholly disassemble the crankset until this piece of metal has been pulled and a new cap acquired. A very large easy out may work, but I might end up having to make something which digs into the remains of the cap and can unscrew it. It’s not very tight, but its not moving.
UPDATE: After a bunch of effort I was able to get the cap out and use a crank puller to remove the crank.
Hello, I have the exact same issue. I’m curious how you got the broken piece out of the crank arm? It does not look like it will be an easy task.
Thanks –
Kevin
Kevin: I carefully cut a slot in the remaining cap without getting through to the threads, then slowly tapped it out using a punch and a hammer. I had to tap it out in a circle after cutting the groove, but I managed to do it and keep the threads intact. I then used a normal crank puller to remove it.
I don’t think I’ll ever use self extracting bolts again, especially not with an alloy cap.
Appreciate the feedback, I’ll give that a shot.
Thanks again.
Kevin
Kevin: Sure thing. It’s a HUGE hassle, but it can be done. Just be careful. Basically, you need to unscrew the cap by tapping it out, and create a small place for the punch / awl to go. It probably took me an hour to do so, then I used the puller to clean up the threads. Now I just don’t have a cap in there at all and pull the crank the old fashioned (and more reliable) way.