I said I pulled up and pushed down. so why are you arguing.
I'm not disagreeing that you can / do push down. You started out from the position of "Im an engineering student and would have expected failure from fatigue on the top of the stem at the weld". I have been attempting to point out (perhaps not very well) that the amount of force that the body is able to apply pushing down upon a handlbar stem is small in comparison with the amount that can be applied pulling back and up. Next time you go up a hill on your bike, see if you can sense the forces being applied.
I had an interesting thing happened to me today. I was on the last hill (a rather steep bugger) of a 60 mile ride and the stem on my Cannondale Multisport 4000 cracked along the weld (I've attached a photo). At first I thought something was loose but then, after a closer look, I found the failure of the weld. I've never crashed the bike so I was very surprised that it happened. I live in the northeast so it's pretty hilly and I've been known to put some torque on the bars when I'm climbing but should this happen? I guess I'm pretty lucky it did not totally fail going down one of the steep hills. Anyone with a similar problem or comments? Thanks.
I too cracked my stem last night at the start of a sprint. I did a search here on cracked stem and this post popped up. It looks like you took a picture of my stem. I have the same crack.
My stem is a Dimension 22.2. It scared the sh@t out of me when my handlebars started going nuts. I am stopping by the LBS on my way home tonight.
id say get a thomson road or mtb stem... mtb is a few more grams but u get a little stronger stem with 4 bolts instead of 2. still both very light stems, probably stronger then what u got.
Maybe you are, but I am not. In a sprint, I am pulling back and up with both arms, bracing against the pedals. The tortional loading comes from one arm pulling harder than the other depending upon which pedal is receiving forward / downward load. I have broken handlebar stems (twice) and handlebars (twice) - tell me how fortunate I am. On all 4 occasions, the movement has been upward and back. The only way you could break a standard handlebar stem across the top would be by putting a 'large' force downwards on it. The only time I could see this happening would be during a crash (and then it's unlikely as your arms would fold at the elbows), or when dubbing your mate on the handlebars while he / she is eating hi / her 4th quarter-pounder for the day.
When a rider performs a "bunnyhop", is there not a transient high downwards force as the rider prepares to take off? I do this pretty frequently.
I had an interesting thing happened to me today. I was on the last hill (a rather steep bugger) of a 60 mile ride and the stem on my Cannondale Multisport 4000 cracked along the weld (I've attached a photo). At first I thought something was loose but then, after a closer look, I found the failure of the weld. I've never crashed the bike so I was very surprised that it happened. I live in the northeast so it's pretty hilly and I've been known to put some torque on the bars when I'm climbing but should this happen? I guess I'm pretty lucky it did not totally fail going down one of the steep hills. Anyone with a similar problem or comments? Thanks.
Cannondale had a stem recall, but I do not thisk is was the same stem.
I too cracked my stem last night at the start of a sprint. I did a search here on cracked stem and this post popped up. It looks like you took a picture of my stem. I have the same crack.
My stem is a Dimension 22.2. It scared the sh@t out of me when my handlebars started going nuts. I am stopping by the LBS on my way home tonight.
I called the Manufacture of the Stem, Quality Bicycle Products, and they said send the stem back and they will replace at no charge.
I have attached a few pictures of the break. [img]file:///G:/MSSONY/IMCIF100/DSC01473.JPG[/img]
