RiceAWay

Carbon seat rails are becoming more and more common. They have now reached the stage where they are normal. I weigh about 200 lbs and am 6'4". The other day I hit a bump along a paved trail and the rails broke and the saddle fell off. I am now back to steel or titanium rails though I prefer steel.

Koyote

1) What kind of saddle was this? Please give the brand and model.
2) What kind of seatpost -- specifically, what sort of clamp?
3) Did you use a torque wrench to install the saddle?

phughes

Lucky it didn't explode.

prj71

Personally I think carbon is bad application for seat rails. I would stick with Titanium.

Maelochs

CF seat rails have been supporting my ginormous mass for quite a few years now but I am sure if I really slammed down vertically ... I mean, anything can fail.

I crossed paths with an MTB rider who had sheared his aluminum seat post. It was a lot more sturdy than my saddle rails.

tomato coupe

I'd bet the answers to these two questions with reveal a lot.

Eric F 

Fixed. Crabon fiber always asplodes.

Trakhak

Load-bearing small-diameter titanium beams can be suspect, too. Stronger than aluminum, but weaker than steel.

phughes

You are correct, and quite apropos considering it was his seat rails.

MoAlpha

Saw a female sprinter break her saddle off in a track competition. That was more about force than mass I’m guessing, but maybe I’m imputing too much competence to her mechanic.

shelbyfv

Good thing you were wearing a helmet!

79pmooney

Serious question - does that seatpost have sharp or near sharp edges to the rail clamps? Especially at the bottom shelf, front and rear. I don't know but I am guessing that a sharp edge would raise the local stress in the saddle rails considerably. Also, was any of the turn up of the rail inside the clamp? Also a stress raiser. I've broken ti rails on both of these.

Koyote

I’ll bet that we don’t get answers to those questions, because the post is a hoax. If this was for real, I’d sure love to see a photo.

Fredo76

Did you use the recommended Silly Putty binder bumpers?

;-)

rsbob 

Bought a set of wheels that came with carbon spokes - three years and no assplosions even after some heavy pothole hits. But they did provide replacements, just in case.

tFUnK

A few of my saddles have carbon rails and while I've not broken anything I am slightly unconfident. Seems like the potential for user error during installation is higher than with metal rails. Even using a torque wrench I can't help but feel nervous. And the oval rails means one needs to be really attentive to ensure their their seat post clamps are appropriate. So far so good, though.

rsbob 

Bring a whole new meaning to the phrase, “Oh snap!”

Sy Reene

Completely unfounded, but if I bothered to get a carbon railed saddle, I do believe I'd be less wary if my saddle clamp was of the style that has a longer platform that the rails sit within (left example?), versus the style that looks more like teeth (eg. middle example).

Koyote

Actually, you've got it backwards: most cf saddle rails are oval-shaped (7x9mm or occasionally 7x10mm), and the horizontal clamp style in the left-most photo will work ONLY if it is specifically designed for the size and shape of those rails. The vertical clamps in the middle and right-most photo will generally be fine with any saddle rails.

But regardless, this OP is a junk post. The poster has been back to bf but not to this thread, even though questions have been raised. It's just another anti-cf troll post. This person has probably never seen a cf-railed saddle, much less owned one.

79pmooney

The left clamp is what I was asking about in my earlier post. The clamp edge being into the start of the turn of the rails. CF doesn't "flow" at all so the concentrated force at that clamp edge will never dissipate. I asked the OP if this was the case so we could all learn but I suspect the hostile replies drove him off.

JohnDThompson 

Especially with saddles and seat posts.

unterhausen

I have a saddle with crabon rails, and it has a warning sticker only to use it on a road bike, no off-road. It matches the paint job of my gravel bike, so that's a bummer. Probably going to use it on my trainer. Ugliest Fizik ever made, but I got a deal on it.

tomato coupe

I doubt that very much.

Koyote

​​​​​It's been a couple days now, and the OP could've easily answered your question (as well as mine) -- or simply provided such info in his initial post. The reason he's not been back is not hostility, but rather the likely fact that the whole thing is fabricated. His post describes a failure that I can't even envision with any saddle: "the rails broke and the saddle fell off." Think about it -- he's claiming that both rails broke simultaneously, and each rail would have to have separated from each end (fore and aft) of the saddle -- all at once. Ever heard of that happening? Yeah, me neither.

Oh, and RiceAWay has a history of anti-cf posts; do you really think a person who regularly rants against cf bikes would own a cf saddle?

Again, I'm happy to be proved wrong. All it will take is a photo of this miraculous saddle failure.

Biker Pete 

2-3 nm torque, RXL carbon saddle and seat post, 175 lb rider on pretty even roads.