crash after stem broke at 50 km/h

[FanieFiets]

 

 

My dad had a crash this weekend at aroud 50 km/h!!!!!!!  KCNC stem on cervelo broke off. Guess riding with a 6.3 kg bike (or something like that) can have its disadvantages. He weights 68 kg so I dont think something like this should happen. Luckily he didnt ge hurt.

 

 

FanieFiets2009-02-11 02:39:36

[KevinV]

Should have posted this on the KCNC Quality thread!

[jaguar]

Eish Fanie! thats hectic. I hope mine doesnt come from the same family?

[calabash]

that is pretty rough

[FanieFiets]

 

Eish Fanie! thats hectic. I hope mine doesnt come from the same family?

 

hahahaha, lets hope not!!!! Hows it going with the training?

 

[Dirtbreath]

Did he manage to control the bike?

[FanieFiets]

 

Did he manage to control the bike?

 

nope! cracked his helmet and some road rash but nothing to serious.

He is very lucky....riding without being able to steer or brake.......not the way to go down a hill!

 

[JPW#]

If you crash at 50km/h.....it should break!

[FanieFiets]

 

If you crash at 50km/h.....it should break!

 

uhm, ride bike then Post breaks off Then crash.  Shouldnt break by just riding it.

 

[bustthesickness]

HECTIC!!!

Wow, he's lucky he didn't completely buy the farm.

 

Could the stem have been overtightened or stressed in any way that you know of? These kinds of failures are interesting to me as even though this component is very light, and designed to have little redundancy they do tend to seem over-engineered in some respects [like the 4 bolt plate for the bar clamp end].

Could it have failed from twisting action? I would be very keen to hear KCNC's response to this.

 

Certainly a big fear of mine, and a critical component to fail, in fact maybe the worst thing that could fail on a bike.

 

[Daft Vader]

Lesson...  Weight weeni-ism is dangerous.  That's why my bike weighs 20kg.

[FanieFiets]

 

HECTIC!!!

Wow' date=' he's lucky he didn't completely buy the farm.

 

Could the stem have been overtightened or stressed in any way that you know of? These kinds of failures are interesting to me as even though this component is very light, and designed to have little redundancy they do tend to seem over-engineered in some respects [like the 4 bolt plate for the bar clamp end'].

Could it have failed from twisting action? I would be very keen to hear KCNC's response to this.

 

Certainly a big fear of mine, and a critical component to fail, in fact maybe the worst thing that could fail on a bike.

 

 

I mailed him the link, hopefully he'll reply later.  The bike was assembled at willie E, dont know if they use torque wrenches or not.

 

[shade]

 

If you crash at 50km/h.....it should break!

 

uhm' date=' ride bike then Post breaks off Then crash.? Shouldnt break by just riding it. [/quote']

 

 

 

then you should change the thread title ! cos like JPW says, crashing at 50km/h a stem is bound to break..

 

 

 

but we glad he is ok..nevertheless..

 

i personally would never fit a KCNC stem or anything of them at the cockpit.. I believe that area is reserved for the more reputable names.. ITM,Easton,Ritchey,3T etc.

 

 

 

 

 

shade2009-02-02 09:00:32

[Jazz]

   See this is exactly the kind of images that goes through my head on a downhill!!!

[bustthesickness]

Judging from the photos it looks like it was perhaps over-torqued. This said though, it could have been dropped at some point and been stressed from that.

If it DID crack from over-torquing then I'd be certain to NEVER use their products again. Things like stems, skewers and cranks need to be made overly strong as in many circumstances they can lead to huge crashes if they fail.

 

[perp]

glad to hear he's ok, always worried with a stem/ bar breaking when taking drop offs at speed.