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Dura Ace 7701 crankset, stripped, what happened?(4 posts)

Dura Ace 7701 crankset, stripped, what happened?Chas
Apr 29, 2001 11:56 AM
Put a new 7701 on my ride, seemed snug, but it stripped the left crank arm on its first ride. Had LBS fix then the right side stripped during first mile of second ride. BB is OK. Has this happeded to anyone else. Maybe my 200 Lbs is too much for the light weight dura ace group? This is a 200 dollar hit and I don't want to lose the replacement.
re: Dura Ace 7701 crankset, stripped, what happened?DrD
Apr 30, 2001 3:14 AM
Just to clarify - which part did you strip off - the bolt which threads into the BB spindle, or the splines on the crank?

If the former, you should be able to get the bolts only (which would be cheaper than a new crankset) If it's the latter, something is wrong - either the crankset wasn't installed properly (you have to be real careful to make sure the splines on the crank engage the ones on the BB - if they "miss" you can still tighten things down so that it "feels" like it's on there, but it won't hold. If they were installed properly, then it's possible that the splines are too wide on the BB or were too narrow on the crank, allowing things to move around a bit when you pedal (or there was a defect on the crank arms - unlikely it would be both sides, though)

I don't think you are too big for the cranks - I can't imagine the setup is a whole lot stronger than the Ultegra, which I use - I am about your size (a little bigger, actually) and have had no problems at all.
re: Dura Ace 7701 crankset, stripped, what happened?Chas
Apr 30, 2001 5:26 AM
The splines are stripped. Its likely I installed them a bit off center. Maybe just caught an edge of the BB splines causing the crankarm splines to crush on the edge making a loose fit between the two. Strange that I would make thew same mistake on both sides. Thanks for your reply.
Points to Installationgrz mnky
Apr 30, 2001 12:57 PM
Looks like you did not ensure that the splines were properly alinged as you tightened up the crank bolt. This is a *very* subtle thing on one must always be careful on this issue. I often advise people to remove the crank bolts with a spanner wrench so that they can feel the splines engaging properly and then installing the bolts. Once you know what to look for you can do it w/out removing the bolts. Sorry to hear that you may have learned this the hard way. :-( Getting the Zinn book may be helpful for future tricky jobs.