Hybrid Bicycles - carbon fork/seat post safe?

I am overweight and am thinking of getting back to cycling for fitness and commute. I am considering a Felt Speed 30 (carbon seat post and fork) and a Jamis Coda Comp (carbon fork). LBS folks assure me that several years of research have gone into carbon structures and should cause no issues when they come from reputed manufacturers.

Yet, I'm seeing several reports of reputed brands failing.

Bontrager (Trek) carbon fork failure: http://www.bustedcarbon.com/2010/01/bontrager-carbon-fiber-fork-failure.html

Seat post failure: http://www.bustedcarbon.com/2010/01/2nd-busted-look-seatpost.html

A failure of the fork or seat post can cause significant injury. How do I determine the max load rating of a carbon part?

Looks like carbon seat posts have failed when the saddle has been set to the rear position. Or when they have developed scuff marks. Or if stressed in a direction other than what they've been designed for. For example, http://www.bikeforums.net/archive/index.php/t-217984.html

I'm confused. Is carbon safe?

Thanks.

I would avoid cf seat posts and forks (and cf bicycles) unless you are into racing and high end performance, spare no expense cycling.

Define overweight. If you're under 250,you should be ok.

Realise that not all cf is created equal. The cf used for street bikes and cross bikes is going to be tougher than the stuff used for racing bikes,where most riders are well under 180 and lightness is a high priority.

Define overweight. If you're under 250,you should be ok.

Realise that not all cf is created equal. The cf used for street bikes and cross bikes is going to be tougher than the stuff used for racing bikes,where most riders are well under 180 and lightness is a high priority.

Yes, I'm under 250. But if I add the weight of the bicycle, the combined weight will be over 250. And, the forces on the bicycle will exceed that as well when the stresses of a bumpy road are added.

It is very possible that I may go from the roadway to the sidewalk via a driveway and back. The transition from roadway to sidewalk is not a smooth one -- there is a lip. And neither the roadway nor the sidewalk are perfectly smooth. Would these cause catastrophic failures?

Has anyone ridden a carbon fork/seat post bicycle on the sidewalk or bumpy roadway?

Thanks.

I think you are well within the stress limits of most cf seatposts and forks. Ellite racing gear being the exception. I've ridden my 225+ pounds all over the place on a cf seatpost and inexpensive cf fork without ANY issues. Curbs, potholes, rumble strips, railroad tracks, no problems. I am a believer in the black stuff. The cf seatpost changed my roadbike significantly. It was a borderline abusive Al frame and the cf seatpost made the ride 10x more comfortable. As for the fork, I wouldn't by an Al bike unless it had a cf fork. A steel framed bike, however, would tend to mute any ride quality bennefit that a cf fork might give you.

It is very possible that I may go from the roadway to the sidewalk via a driveway and back. The transition from roadway to sidewalk is not a smooth one -- there is a lip. And neither the roadway nor the sidewalk are perfectly smooth. Would these cause catastrophic failures?

Has anyone ridden a carbon fork/seat post bicycle on the sidewalk or bumpy roadway?


You've never watched cyclocross racing.

As long as you're not bombing down steps and hucking off loading docks,you'll be fine.

You've never watched cyclocross racing.

As long as you're not bombing down steps and hucking off loading docks,you'll be fine.

Folks, Your responses are most reassuring. Thanks!