Catastrophic crank fail

You know more than me regarding track gear. But general bike gear seldom gets tougher, as you go up the hierarchy. weight figures become increasingly prioritised. This is exactly why I stick with standard deore stuff for the work horse.

cheap strong light, pick two.
but yea pretty clear that crack has been there for while.

I'd previously thought sugino messengers had a good rep, but sounds like theres been quite a few failures, albeit all have propagated over time as far as I'm concerned it shouldn't happen!*

*if you are using the right crank for the right job. e.g. if you were using a super lightweight touring/ racing crank I would not expect it to put up with years of abusive fixed/ single/ out of the saddle riding.

I used to ride DH/mtb a LOT, probably out 30hours a week or more on my bike doing various things and I've never had a crank fail, not even shitbox OE ones that I'd borrowed from a mate (when a gen1 hollowtech bb failed after a few weeks of use). Between our group of riders we would tend to buy the same kit, as you do, one guy gets something new, then the others would want. ANd from teh larger commuinity if we had a repetitive failure, cranks/pedal axles/ suspension linkages/forks/ h'bars etc we would as a group ditch the product and move on.

What I'm saying is, why has Sugino themselves not responded to a number of their messenger cranks snapping through general use leading to various minor accidents (thankfully none more serious yet)?

How many have snapped?
How many owners have informed Sugino about it?
I bet both numbers are pretty low.

True.

But generally for everyone you know about, there are 10 more that you don't (applies to tonnes of things, and IS obviously a very general analogy).
From descrip/posts/photos they appear to have snapped in a similar place.

I wouldn't brush the lot with saying 'all messenger cranks are fail', but if I ever owned a set, I'd probably be checking them over.

That crack has definitley been there a while, you can even see the 'tide' marks where it's propogated over time. Classic fatigue failure.

^ This

As every 1st year Mechanical Engineering student knows. Coulda been worse. Coulda been a 50's airliner. Oh, wait...

Points to manufacturing fault such as a casting void or inclusion, or as someone said a sharp indentation causing a stress-raiser. Then add 300,000 low-stress cycles,...

CasaSteve, doubt there's anything you could have done to foresee/prevent this, but I would deffo try send back to the manufacturer if I were you, to feed back into their Engineering dept and maybe prevent future ocurrences? Or get you a new set of cranks?

Heal up dude.

I'd previously thought sugino messengers had a good rep, but sounds like theres been quite a few failures, albeit all have propagated over time as far as I'm concerned it shouldn't happen!*

*if you are using the right crank for the right job. e.g. if you were using a super lightweight touring/ racing crank I would not expect it to put up with years of abusive fixed/ single/ out of the saddle riding.

I used to ride DH/mtb a LOT, probably out 30hours a week or more on my bike doing various things and I've never had a crank fail, not even shitbox OE ones that I'd borrowed from a mate (when a gen1 hollowtech bb failed after a few weeks of use). Between our group of riders we would tend to buy the same kit, as you do, one guy gets something new, then the others would want. ANd from teh larger commuinity if we had a repetitive failure, cranks/pedal axles/ suspension linkages/forks/ h'bars etc we would as a group ditch the product and move on.

What I'm saying is, why has Sugino themselves not responded to a number of their messenger cranks snapping through general use leading to various minor accidents (thankfully none more serious yet)?

had the same thought

I'm a clumsy rider too, not lardy, just lazy so I tended to go hard on components.

Had this happen yesterday,heard a loud bang then the next thing i new was that the bike was riding me.Is this a known problem? bought new around 18 months ago.

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^^ Tapers look a bit mashed up, been on the wrong BB taper / over torqued perhaps? Some cranks are very sensitive to it, and being records they'll likely be fairly specific on the required torque value.

Also that break looks like it has a newer and an older part to it. Upper part of the sheer is darker/tarnished vs. the lower parts more shiny appearance, would suggest its been propagating for a while?
I had a set of middleburn RS7's that I cracked the left hand from edge of taper to edge, rode home, didn't get worse but could feel it flexing out, they replaced it, then a few years later it happened again pretty sure crank had never been off in that time either. They won't replace this time as they are a new company so older products warranty is now VOID AFAIK.

My non expert opinion is like Brickman's .. looks like it's been installed incorrectly which has caused the eventual failure ..sorry fella

Was fitted to campagnolo pista bb,not over torqued.I did have a problem with a crank extractor trying to remove them,so fitted self extracting bolts.when I did that they came off easily.rode after this for a year with no problem.had just fitted them to a miche bb(campy one too wide)and then out for testing. Do you think the miche had a different taper,or the extractor could have affected it?

Old news but this was my effort when pulling away from lights at Angel last year - thankfully no cars immediately behind but I had a massive bruise on the inside of my thigh and the crowd on the pavement thought a rifle had been fired.

You should complain to the manufacturer...

"Dear France, why did you 30 year old cranks give up on me? Regards, CYOA"

Exackerly.

It's an excuse to go an shout at a French octogenarian.

Not that excuses are needed.

Old news but this was my effort when pulling away from lights at Angel last year - thankfully no cars immediately behind but I had a massive bruise on the inside of my thigh and the crowd on the pavement thought a rifle had been fired.

Mate what crankset is/was that? Looks old style, any creaking noise before it went?

Same happened to me last summer. Vintage Campag. Never again. Great scar on my knee though (see last page).

And no, know evidence to suggest it would break. It just did.

It was an old stronglight from memory. Or maybe a TA. It was a while ago and I didn't have it for long. There was nothing externally to suggest it was on the way out. No noise either.

The moral of the story is - don't get "vintage" cranks. Or any parts you intend to actually use.

Ok wow thats freaked me a bit there, just out of interest were you guys off the seat or seated when your cranks failed? Full weight on the pedals and that?

It was an old stronglight from memory. Or maybe a TA. It was a while ago and I didn't have it for long. There was nothing externally to suggest it was on the way out. No noise either.

The moral of the story is - don't get "vintage" cranks. Or any parts you intend to actually use.

dont say that! everything i use is vintage...

Ok wow thats freaked me a bit there, just out of interest were you guys off the seat or seated when your cranks failed? Full weight on the pedals and that?

I was pushing off, going slightly uphill. I've always been told that cranks and hubs are the most important parts to invest money in.

The moral of the story is - don't get "vintage" cranks. Or any parts you intend to actually use.

Vintage steel bits are stronger than modern alu.

^lol

http://youtu.be/MywPODYZ85U?t=1m48s