Crank snapped!

kumate_champ07

I was stopped at the traffic lights coming into Tempelouge and they turned green, put the foot down and snap!! the pedal and about 1/3 of the crank fell to the ground. It got me thinking later if it could have happened on a high speed decent or was it a high stress fracture due to acceleration from a stationary start.

Is this a rare thing?

Ive only had the crank about 3 weeks, bought it second hand from ebay but the guy had painted it white and put a decal on it, the listing was in spanish so not sure if he claimed it to be something it wasnt.

Golfanatic

are you looking for a new one how long do you need it

Dr_Colossus

This probably should be in the cycling forum rather than the Cycling Adverts.

That sounds nearly impossible, had to be a faulty or previously cracked crank with a cover up repair job with the white paint. No way a normal crank snaps under any normal use. What make or type of crank was it?

kumate_champ07

oops wrong forum, ye it looks strange at the area where it separated

Lumen

Moved from Cycling Adverts to main Cycling forum.

8kvscdpglqnyr4

About 12 years ago, I used to commute to work on a mountain bike (with slicks) - it was an OK bike ... can't even remember what Shimano groupset was on it.

Coming home from work one evening, the left crank broke. I didn't think too much of it at the time and just got it fixed. About 3 months after that, the right crank broke! At that point I was really pissed off because it happened at high speed on a roundabout over the M50 ... my manhood came down hard on the crossbar! I was not a happy camper.

I looked up the Shimano website, found an area on the site dedicated to recalls and sure enough, my crankset was listed (there was a serial number on the crank that matched that on the website).

My LBS sent the broken crank back to Shimano and they sent out a brand new left + right crank.

Just looking back through old emails - this is where I read about the crank at the time:
http://www.cpsc.gov/cpscpub/prerel/prhtml97/97149.html

'68 Fastback

Hey,

Breaking a crank takes alot more than a stationary start in a low gear and I know nothing about the physics. I do have an old Deore MTB crank for a square taper BB. 170mm arm length. 22,32,44 rings i think.

Its yours foc if you want it.

Deisetrek

Dr_Colossus wrote: »

This probably should be in the cycling forum rather than the Cycling Adverts.

That sounds nearly impossible, had to be a faulty or previously cracked crank with a cover up repair job with the white paint. No way a normal crank snaps under any normal use. What make or type of crank was it?

Have to correct you there , it certainly can fail under normal use I have been on this forum before describing how the left crank ( Shimano tiagra) snapped on my Trek 1000 road bike last year . Bike was 2 years old and I was very lucky , coming up a hill pushing hard out of the saddle .....SNAP with crank and SPD pedal attached to my shoe ...ended up in a ditch . Luckily it was the left crank , if it had been the drive-side crank I was out into the middle of the road into traffic . Stress fractures can occur in any castings if air gets in during the casting process , certainly not unheard of ........

kumate_champ07

just thought I'd update the thread, it turns out the crank had been drilled by a previous owner as I coincidentally bought the same model again but in original unpainted and undrilled form

the holes werent very symmetrical, the crank was actually decent but structurally flawed, a shimano model 600 which became the ultegra line.


the holes werent visible in the ebay pictures, member doesnt exist anymore but he had 100% feedback over the years.

I'm lucky it broke at traffic lights and not a Wicklow mountain decent!

also had a quill stem fail last nite, also lucky that didnt happen a few days ago in the Donegal moutains! bolt came right thru to the back, the handlebars became a little loose a few days ago which I noticed after heavy breaking and a quick stop as my weight shifted forward.

snollup

kumate_champ07 wrote: »

just thought I'd update the thread, it turns out the crank had been drilled by a previous owner as I coincidentally bought the same model again but in original unpainted and undrilled form

the holes werent very symmetrical, the crank was actually decent but structurally flawed, a shimano model 600 which became the ultegra line.


the holes werent visible in the ebay pictures, member doesnt exist anymore but he had 100% feedback over the years.

I'm lucky it broke at traffic lights and not a Wicklow mountain decent!

also had a quill stem fail last nite, also lucky that didnt happen a few days ago in the Donegal moutains! bolt came right thru to the back, the handlebars became a little loose a few days ago which I noticed after heavy breaking and a quick stop as my weight shifted forward.

God your having a run of it. Be on your guard as dont they say things happen in 3's.