Mountain Biking - F*** Carbon Fiber!

Went mountain biking with a friend over at the Barton Springs Greenbelt in Austin, TX...we were planning on a ~2 hour, 20 mile ride...half a mile into the ride this happened:

http://www.hi-upload.com/upload/uploaded10/mini-IMG_0474.JPG

Carbon Fiber seat post snapped resulting in injury on my knee (scrapped up) and tweaked my left hand pretty bad...spent about 20 minutes trying to remove the remaining portion of the seatpost so we could stick the rest of the seat back on and finish the ride, but weren't able to with the tools we had and ended up turning back. NO more CF Mountain bike seatposts for me.

Oh ya, and if anyone was wondering, it DID NOT snap where the frame of the bike starts...it snapped about 1 inch above that. Not exactly sure why...

it happens.

did you use a torque wrench when you installed it?

I use a CF seatpost on the road, but not sure I'd want to use it on a mountain bike . . . even before I saw your post!

mountain bikes take serious odd loads when either landed improperly or simply crashed.

would never use a CF post on an MTB unless it was my race rig dedicated to racing. on my training bike or any other MTB, aluminum only....

just too many times the post would get nailed at the wrong
angle and weaken it

I really like CF and I think it's a beautiful material in so many ways. I have used it with some of my work projects, and it just allows certain shapes and designs that are not possible with other materials.

But for me, NOT for mountain biking. It's just too susceptible to stress-risers from nicks and scratches... and when it lets go, it's almost always catastrophic and with no warning. I like a MTB that can be crashed, picked-up and thrown into battle again without worrying about material stress.

In controlled racing conditions with support and replacement contingencies, yes... but otherwise...

.

Carbon sucks...no really, it does.

^ If I had to use only 6 words... yep, that's about it (for mountain biking). :lol:

did you use a torque wrench when you installed it?

What would that have to do with it if it broke an inch above the clamp?

OP--I allow no carbon on my mountain bikes after having seen several bars and seatposts and other carbon bits fail on others' bikes (and having my Trek OCLV bonding fail twice, that bike is ridden very infrequently and carefully now). I don't race (anymore), and want my bike to be able to crash with minimal worry. I know aluminum can break, too, but the one time I messed up an aluminum seatpost it bent and got me home.

I dunno, I've got an 05 carbon frame, seatpost, saddle and bars,
that say your a bunch -O- hacks He He

http://www.hi-upload.com/upload/uploaded10/mini-IMG_0474.JPG

DID NOT snap where the frame of the bike starts...it snapped about 1 inch above that. Not exactly sure why...

Where is the piece that was still in the seat tube?

Ha, carbon fearing mary's ha ha ha

I'll break my carbon foot off in yo saddle.

Buncha hacks.........

You're "lucky" that you seem to be riding a Cannondale and not a bikes-direct bike. You would have stoked the fires of the BD-haters out there, but seems like C-dale is relatively immune to hardware failure criticism, at least with regards to their road bikes.

did you use a torque wrench when you installed it?


Out of curiosity, whose torque specs do you use? Those of the framemaker, the seatpost maker, or the clamp maker? Torque specs on bike parts seem to be quite hard to come by.

You're "lucky" that you seem to be riding a Cannondale and not a bikes-direct bike. You would have stoked the fires of the BD-haters out there, but seems like C-dale is relatively immune to hardware failure criticism, at least with regards to their road bikes.

Looks like a specialized seatpost. I've been wrong before though.

Deff. not a stock seat post. Unless cannondale is putting more expensive parts on cheaper bikes now.

I dunno, I've got an 05 carbon frame, seatpost, saddle and bars,
that say your a bunch -O- hacks He He

Yeah, but you're in Kansas, too.

let me see if i can answer all the questions...

I don't know if a torque wrench was used on install as this was my friends bike, but as someone else mentioned, im not sure how much that would affect it since it snapped an inch above the frame

I personally wouldn't use a carbon MTB for general riding (especially after this experience)...i have carbon forks and seatpost on my roadbike, but that doesn't experience the type of stress a mtb would

The piece that was stuck in there, we were able to remove it with pliers...sorry no picture, but if your wondering if we had it in far enough, it was well past the "limit" marker on the stem ( i would say the piece was about a good 4 inches)

This wasn't a stock seatpost, however it was not specialized either...it was one of the more expensive companies...i can't remember, as the bike is my friends...

the only stock piece on that bike is the frame...everything else has been swapped

Pro-rider turns up from overseas with preferred (brand new) carbon bar... installed it that morning... loaded three test bikes on a car rack as we normally do. At the end of one day I spot this nick while unloading the bikes. :(

It's probably fine (although no one would guarantee it safe for hucking or jumping)...
Pro-rider didn't want it back, so leaves it behind. No one else wanted it either, so it ends up on my commuter bike. :) :thumb:

It's not on my MTBs because I just can't be bothered stuffing-around with paddings to protect it during rack transport. Didn't mean to sound too critical, but that's just me and my circumstances.




http://i156.photobucket.com/albums/t24/Rollopics/carbon-bar-01.jpg

I'll break my carbon foot off in yo saddle.
He He you'll never catch me on that heavy aluminum sled your riding.

He He you'll never catch me on that heavy aluminum sled your riding.

Contraire...one day you'll be a freerider and wanna go huck yourself...but you won't wanna tear up the Epic or XTC...you'll be too proud of the 575 or Heckler to wanna huck it...so you'll break into my shop and do some "black-op's" hucking downtown one lonely summer night when I'm outta town. The only evidence of your mission will be the urine stain on my Komodo from that BIG OL' stair-gap at the Post Office:roflmao2:

There's a law against riding on the sidewalks downtown.

You guys need to come out here and boost the stairs at the Spokane Arena. Great fun.

http://www.spokaneplanning.org/images/Spokane%20Arena3.jpg

Gnar-freakin'-drool

Hope this doesn't come back to bite me in the ass but I trust mine. It's been through a couple of falls... nothing too gnarly but it's got a battle scar or two. I run carbon bars and forks.

Hope this doesn't come back to bite me in the ass but I trust mine. It's been through a couple of falls... nothing too gnarly but it's got a battle scar or two. I run carbon bars and forks.

You done ****ed up, man. :lol:

Carbon for Road- Good!
Carbon for MTB- not so much.

At least for me. I'm rough on stuff.

Carbon for Road- Good!
Carbon for MTB- not so much.

At least for me. I'm rough on stuff.

http://www.chinamtb.com/files/page0_blog_entry121_1.jpg

Yeah, carbon fiber's crap for rough stuff. And 29ers too.


Wait... I thought you said CF was bad for rough stuff. LOLOLOLOL IGNORE ME I SUCK

^^ I was going to let it go this time. Thanks you for saving me the trouble of finding a fresh pic.

You guys need to come out here and boost the stairs at the Spokane Arena. Great fun.

http://www.spokaneplanning.org/images/Spokane%20Arena3.jpg

We've had races at the school in Saluda NC......

http://i173.photobucket.com/albums/w69/mtnbiker66/05street004.jpg

We've had races at the school in Saluda NC......

http://i173.photobucket.com/albums/w69/mtnbiker66/05street004.jpgI see a roof-to-grassy-slope-tranny opportunity there.


But not for me.

BTW, one of my goals this year is to clear a landing section on the Arena stairs to hit the next flight as a tranny. Haven't gotten up the speed (or courage) yet to hit it that hard.

In my earlier road biking days I had 2 seat posts break. most likely from just good ol hard riding on hills.

Arena stairs

Pic's?

There's this one not far from my house...it's pretty huge.
http://www.missouriminutemen.com/images/images/10/0/Image/landon1.jpg
Something about being there makes it much bigger.
http://i60.photobucket.com/albums/h28/chelboed/Bike/n501173445_110481_3092.jpg
First set looks to be ~20 steps down...the flat between sets is longer than it looks. I've never been man enough to do it.

First set looks to be ~20 steps down...the flat between sets is longer than it looks. I've never been man enough to do it.

Sorry, are you meaning - just riding down it, or - speed hucking from the top, to the middle flat, to the bottom flat, without riding over the steps?

.

He means jumping from the top and landing on the second flight, clearing the middle flat portion and the top stairs.

^ Oh... ok... yep...

Sheesh!

If anyone pulls it off, please don't forget to put it on YouTube!

Ooops sorry, we were talking about carbon weren't we... :o

.

I went down those steps on a carbon HT. Made for a pretty bumpy ride. Time i got to the bottom, my glasses were cockeyed.

I was checking out a new CF Stumpjumper in the shop today.....7000.00.....wow.

^ Oh... ok... yep...

Sheesh!

If anyone pulls it off, please don't forget to put it on YouTube!

It's really not as big as some of the gaps on "Jib".

There's this one not far from my house...it's pretty huge.
http://www.missouriminutemen.com/images/images/10/0/Image/landon1.jpg
Something about being there makes it much bigger.
http://i60.photobucket.com/albums/h28/chelboed/Bike/n501173445_110481_3092.jpg
First set looks to be ~20 steps down...the flat between sets is longer than it looks. I've never been man enough to do it.

Where is that? Looks like this stadium place in St Charles, Missouri.

Where is that? Looks like this stadium place in St Charles, Missouri.

Kansas Expocentre, Topeka

http://img207.imageshack.us/img207/488/imgc20070513914301v800.jpg

Homemade DH frame.

http://www.carbonmike.sk/Evolution_I.htm

Yeah, he's used some interesting molding - - and he's done a one-off private copy of the VPP (which is not infringing on the patent since it was for personal use). Some good work there. Other homemades:

Derek Lahr, a doctoral candidate at Virginia Tech (and a real friendly and interesting guy to talk to):

http://3.bp.blogspot.com/_wgDeoguscbo/R54MPe0tniI/AAAAAAAAACc/7kqMV5QzyCo/s1600/DSC00443.JPG

He built that to house his REAL project - - a CVT:

http://3.bp.blogspot.com/_wgDeoguscbo/R8rj9-3zpUI/AAAAAAAAADE/U8F0mwNocj0/s1600/first_assembled.jpg

And my favorite mad scientist, road trip partner and Masters Worlds roomie Alex Morgan (Buffalo Composite Designs):

http://bcdracing.com/frames/sanjay/DSC00507.JPG

But it's so ugly, Doug...what shoes would I possibly wear that would go well with that chunky neanderthal looking frame? (raises pinky, sits cross-legged)

Another Slovakian home-made frame:
http://img527.imageshack.us/img527/5118/promo08small.jpg

http://www.mwbikes.com

But it's so ugly, Doug...what shoes would I possibly wear that would go well with that chunky neanderthal looking frame? (raises pinky, sits cross-legged):roflmao2: Some beat-up Chuck Taylors would go well with the cobby garage-fab look, I believe. Extra points if there's uncured boat resin drizzled on the toes.

:roflmao2: Some beat-up Chuck Taylors would go well with the cobby garage-fab look, I believe. Extra points if there's uncured boat resin drizzled on the toes.

Speaking of resin...

There are resins that require curing in an oven, that are sometimes used for CF lamination. Is oven-curing CF used for bike frames? The Carbon Mike and MWBike frames used resin that cures in air at room temp (I think). What is the reason for the air curing vs oven-curing? Is one stronger than the other?