I lost my crankarm!!

[Sandy]

So I have this beautiful Ottrott ST which I have ridden and enjoyed for about 1200 miles. Yesterday I went on a short ride down to the park and back. On the way down to the park, I found it more and more difficult to shift into the big chainring. When I got to the park, I could not shift into the big ring at all. The deraileur would move but the chain would not go to the big ring. On the way back, I was about 1 mile from my house and stood up, off the saddle, and started to pedal. Very quickly I realized that the left crankarm of my new Dura-Ace 10 crankset was attached to my pedal which was attached to my shoe, but the crank arm was not attached to the bb axle. Luckily, I extended my shoe/pedal/crankarm and placed the threesome (don't get excited Kevan) on the ground and safely stopped. I think I was most fortunate in that I did not have an accident.

It turns out, that the crankarm is held on by a small hexagonal bolt type mechanism similar to that which holds on a seatpost. That was somewhat surprising to me, since the forces applied to a crankarm certainly can be a lot, especially with my weight.

The pedal now seems to have a rattle, as a result of rubbing against the ground, I guess. I am going to take the bike into the shop now to see what they have to say. I would appreciate any comments and suggestions that you could give me so that this will not happen again.

THANKS,


Cranky Serotta Sandy

[Kevin]

Sandy,

I am glad that you are ok. It sounds like a harrowing experience. But is does make a great headline. Super Sandy Snaps Shimano.

Kevin

[gt6267a]

sandy : i am glad it worked it out so nicely. there are a few people on this forum who have had like experiences and found themselves shredding flesh on the pagement, myself included. i am wondering who attached the crank and if there is some reasoning behind the bolt undoing.

-k

[jeffg]

Serendipitously Safe Snapping Shimano Sandy

[Jeff N.]

Sandy: In addition to that hex bolt, there are two allen screws, one on either side of the crank arm, that need to be torqued down after you hand-tighten the outer hex nut...an arrangement not unlike your threadless stem. They HAD to have been loose. There is no other explanation to your mis-hap.

[SPOKE]

Ouch! glad you're ok Sandy. seems that the 2 pinch blots on the crank arm were not properly tightened. i also think they owe you a new crankarm and possibly a pedal too because i'm sure the crankarm got plenty of scrapes and such.

[Too Tall]

So was I the last person to see you intact? Sheesh, glad you are OK big fella. Like the man said, you are not at fault. Now practice saying this with me before you confront the shop "holy cow, I was just riding along and the darn crank arm came off. Sure is a good thing a truck or something was not heading right at me (cough cough)." And remember to smile alot.

[Johny]

Glad you are OK too!
It is time to use Campy! Kidding aside, hope that they will replace it with a new one...

[Kevan]

Ooooo....that felt so good to say!

Sans-mans, get on back to that shop and tell them who they're dealing with; that nothing less than what the pros get in service is what you deserve. You're a monster out there, they best know it!

Glad you're safe my petunia.

[Needs Help]

It's good to hear you're OK. Scary to read about.

[Sandy]

Thanks for the kind thoughts. I did take the bike into the LBS.I really did not notice until I got to the shop that the little cap on the outside of the crankarm was completely missing. They had to remove one from another bike and use it on my bike. I think that when the cap came loose the axle started to move away from the bike slightly, such that the bike would not shift into the big chainring. Once that cap is tightened some, I believe, everything is aligned and then the other bolt (hexagonal) must be tightened to hold the crankarm securely.

I have about 1200 miles and I was told that if the crank was not put on properly, then the problem would have occurred within the first 200 miles. What do you think? There is now a significant rattle in the Look CX-6 pedal and the shop does not know how to address that and I was told that they would contact Look to see what to do. The crank is scraped.

Should they be responsible for a new pedal and a new crankarm?

Still Spinning Some Serotta

[Sandy]

Since Too Tall was the last cyclist to see me before my problem, is it possible to hold him responsible for the mishap, and most if not all of the world's problems?

Silly Sandy

I think they owe you a new pedal and a new crank arm. I might not have thought they owed you a pedal until they told you the somewhat insulting story that suggests an improperly mounted crankarm would have been identified in the first 200 miles. If it were grossly malmounted I would agree, could have been put on so poorly it fell off the first time you rode the bike. It sounds to me like the crankarm bolts weren't properly torqued and it gradually loosened up. That can take a while. There was obviously a rapid loosening once it got to a certain point, that would not be surprising. The only other options would be a manufacturing defect (did the bolt strip?) or a design flaw that demands you tighten the bolts every thousand miles. The former would be obvious, the latter should have been identified long ago by others using this crankset.

I'd like to hear others opinions, but I can't imagine other possibilities.

I'm also glad you are OK. Reminds me of the time I changed pedals on my daughters bike and one fell off because I didn't tighten it properly. She was OK too. I also had a pedal break off my English 3-speed 35 years ago or so. I still have a big divot in one knee from that experience.

[Jeff N.]

Who installed the crankset? You or your LBS or ??? Made me go out and check the DA-10 crankset on my Moots. Everything was snug, after about 600 miles. I once has a pedal strip right off a p.o.s. ZIPP carbon crankset(a whole nuther story).You ain't lived until you've pedaled 20 or so miles with one leg! Again, glad you're not hurt. Jeff N.

[SPOKE]

here's the deal..........when installing the crank the left crankarm (non-drive side) is slipped onto the splined axle and snugged into place with the threaded dust cap. once snug then the two pinch bolts on the crankarm are torqued to spec which locks the crankarm onto the axle as well as locks the dust cap into place. my bet is the crankarm pinch bolts were A) not properly torqued, B) managed to work loose which doesn't make a bunch of sense since the spline in the crankarm meshes so well with the spline on the axle or C) one or both of the pinch bolts broke due to a bad bolt or too much torque.
bottom line is i think the LBS messed up. send a note to shimano USA to get another opinion. i bet they point to the LBS providing there is no defect that can be identified.