Snapped crank spindle.

[SkipdiverJohn]

I was sprinting up a short steepish hill on my singlespeed bike last year when I heard a strange clicking sound. I didn't want to 'do a Duncroft Avenue' so I sat down and just as I was safely back on the saddle my chain snapped!

The risk of sudden mechanical failure or losing traction due to swaying side to side on a greasy surface, is the reason I never pedal standing up. If I can't get up something whilst seated in my lowest available gear, I get off and walk it.

 

[ColinJ]

The risk of sudden mechanical failure or losing traction due to swaying side to side on a greasy surface, is the reason I never pedal standing up. If I can't get up something whilst seated in my lowest available gear, I get off and walk it.

I have very low gears on my other bikes so I can get up most things still seated, but once it gets to 20+% then it is pretty tough not to stand for the worst ramps.

My singlespeed gear is 72 inches and I wouldn't get up anything steeper than about 8% in that without standing up!

There are MANY steep hills round here so I would have to do an awful lot of walking if I never stood up on the bike.

 

[Smokin Joe]

I've never heard of a square taper failure though.

Neither have I. I've no doubt it has happened to someone, somewhere, but never enough to be the slightest risk to most of us. Hollowtech does seem to throw up frequent examples of broken axles.

 

[johnblack]

I well remember the sight of a mate spinning at 110 up a short steep climb, all of a sudden seeing his right leg flapping with just a pedal and crank arm attached.

 

[Foghat]

I've no doubt it has happened to someone, somewhere

Not since 1982......

 

[Ajax Bay]

I've never heard of a square taper failure though

Not since 1982......

OK, let's just amend it to 'square taper steel spindle' failure.
Thanks for the image! Fignon's broken BB spindle was titanium (as I bet you know). The spindle had been made with the same dimensions as a 'normal' steel spindle (to fit the steel cups) but made from a lighter, inferior in strength material. Presumably the idea was that the few grams saved justified the shorter lifespan and likely breakage. A 'gamble' (connect other thread) that didn't pay off (aka 'failed') with minimal 'upside' and demonstrable 'downside'.

 

[nickyboy]

Just to add to the horror pictures, here's my failed Shimano Hollowtech from a month or so ago

 

[I like Skol]

Just to add to the horror pictures, here's my failed Shimano Hollowtech from a month or so ago View attachment 572179

It was ok once we welded it back up....

 

[Ajax Bay]

So have you converted (back) to a square taper yet? Seems only sensible, you being a gambling person, an' all.

 

[Foghat]

OK, let's just amend it to 'square taper steel spindle' failure.

Fignon's broken BB spindle was titanium (as I bet you know)

Er, well yes.....that incident put me off ever contemplating a titanium bottom bracket axle again.

But the key words were 'not since 1982', reinforcing the notion that failure of square-taper bottom brackets is vanishingly rare. If I had been trying to assert that such breakages are more common than people think, I might have posted the image below.....but I wasn't! Anyway, the clarifications you went on to make for viewers add some useful context to the incident of 38 years ago.