UKC

Sheared crank axel

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Morning,

I was out for a ride over the weekend and had a pretty spectacular mechanical failure.
I was on fairly flat ground, stood up to put some power down and there was a huge "bang" and my left foot hit the ground sending me into a big old wobble. I just managed to stay upright/avoid the oncoming traffic.
I thought the pedal had come off but when I came to a standstill I looked down....to my horror, the entire non drive side crank arm had disappeared! All that remained was the small jagged protrusion of axel (1-2mm)

Queue pedalling 1 legged to the nearest train station.

I've been googling like mad but can't find any answers as to how this could happen. I take care of my bike. It never sleeps in the rain and I use a torque wrench for tightening etc, although even if I treated the thing like s**t I'd never expect that to happen. Anyone heard of such a thing? I'm utterly miffed and annoyed, but feel quite fortunate I didn't eat tarmac!

It's a FSA Gossamer crankset similar to the Hollowtech system.

Cheers,
Lloyd
 Escher 18 May 2015
In reply to adventure_vulture:

Are you talking about the bottom bracket? That a section of it has sheared off and remains attached to the middle of the crankarm? It may be a different problem to
yours but i know someone who has snapped three cranks and they were all FSA.

sounds like too much of a coincidence to me. I would get a refund as it is not fit for purpose and fit a different make of a crank.

I'll ask my mate exactly what his issue was and report back.
 arctickev 18 May 2015
In reply to adventure_vulture:

sounds like shear failure of Bottom Bracket.

How old?

Kev
 Escher 18 May 2015
In reply to adventure_vulture:

My mates problem doesn't seem to be the same as yours but he mentioned this http://www.fullspeedahead.com/support/recall/gossamer-bb30-recall-notice/
In reply to adventure_vulture:

Hi guys,

Escher- Interesting to hear that your mate has been breaking FSA stuff on the regular!
I've bought a shimano crankset to replace it.

Kev- The bike is about 3 years old. Gets ridden about 3 times a week, 30 - 100 miles.

The BB is intact, it's the axle that connects the two crank arms that has sheared. I've uploaded a rudimentary diagram so you can see what I mean. I'll post a link here when it's approved.

Lloyd
 Sir Chasm 18 May 2015
In reply to adventure_vulture:

My guess is that at some point your NDS bearing seized, so the axle has been grinding against the non-rotating inner bearing.
 ThunderCat 18 May 2015
In reply to adventure_vulture:

Had this myself about 2 years ago. I was 'luckily' at a standstill and just moving off to cross a road. I ended up on the floor with a the couple of bruised ribs from the handlebar. Since I was at a junction when it happened I can draw some solace from the fact that I gave about 50 drivers and a tram fill of commuters a good laugh.

The bike was quite old, but not 'that' old. Put it down to bad luck, basically.

Bizarrely, I'd witnessed it happen to someone else who was cycling in front of me about 2 weeks previously.

I really do dread to think what would have happened if I'd been moving, at a busy bit of road.
 krikoman 18 May 2015
In reply to adventure_vulture:

I've seem a broken crank before but it was pretty obvious there had been a defect in the material.

There was rush part way into the break, so the shaft had been cracked before it sheared.

did you keep the bits?
 AlisonSmiles 18 May 2015
In reply to adventure_vulture:

This (I think) happened to my fella with a Campagnolo Chorus. He was setting off from red lights and there was a sudden discovery that his foot remained clipped into a pedal on a crank arm which had sheered. I came to the lights to find him helplessly waving said object at me. He phoned a friend, I rode on. I think he sent it back to manufacturer, not for replacement but so they could check it out.
 Mike Highbury 18 May 2015
In reply to arctickev: It happens; to Fignon, famously (titanium BB axle in the Paris Tours)

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