Carbon seat stays

mrtuk

Are they any good? Marin seem to do a couple of models with these on, but i was just wondering if anyone has any experience of them?

The benefit as I understand it is:
a) lighter (not sure how much diff there really is though)
b) absorb shock so more comfy ride !

However I'd just be a little concerned about whether they could 'snap' ... or at least fracture and render the whole bike useless? I think that Marin frames come with a lifetime warranty, but again not sure if something happened iin that area that they would put it down to accidental damage and hence not cover it?

Thoughts/opinions?

Cheers

explosifpete

They wont snap but they don't really make any difference to the ride other than looking nice

lycraholic

I had (note the past tense) a Spesh Allez 2010 with carbon seatstays. You can see the photo here: http://www.evanscycles.com/product_image/image/2b6/6ee/8b9/39158/large/specialized-allez-comp-2010-road-bike.jpg There is a very weird little section of carbon on the lower bit of the seatstays, in other words the carbon bonds into a slot just above the dropout, and into an aluminium bit coming off the seat cluster.

Sadly due to a rather unobservant driver my rear triangle smashed into their bumper on impact and the right hand side rear dropout, not just the derailleur hanger, became bent inwards, thus writing off the frame. I can't say for certain that this wouldn't have happened if the seatstay was all alu- but I cannot think that the aluminium/carbon bonding would be as resistant to impact. In performance terms I couldn't tell any difference anyway.

But take this with a pinch of salt, as per usual.

CarlosDSanchez

My specialized sirrus elite has them and it's a more comfortable ride than my cube agree which doesn't (run both with 23mm tyres btw)

Certainly feels like it takes some of the road vibrations out of the ride, but they are very different bikes.

Headhuunter

The main reason manufacturers provide carbon forks and seatstays is ride comfort, I don't think there is a huge weight saving. Carbon absorbs far more road buzz than alu and even steel or ti frames. It is fairly noticeable, sometimes when I switch to my carbon bike from an alu bike I have to check that I haven't got a puncture as the ride is smoother. Road buzz mainly comes up from the wheels through the forks and rear stays, so those are the most effective parts to "carbon-ise". Other than that there is little advantage.

As for durability, I've been riding a full carbon bike for thousands of miles through rain, sun, snow and over potholes along dusty, stony tracks and on normal roads and nothing has "snapped" yet!

bails87

I got hit by a car when on my carbon road bike. The bike was fine, I wasn't.

Also, my MTB is carbon, you should hear the noise it makes when rocks thump off the downtube!

mrtuk

Thanks for the replies ... has eased my concerns that it'll make the frame more fragile, but seems like it's as much a cosmetic thing as any real 'value'. I think that making it sexier is a bad thing too if it's not really adding much to the riding experience as it's more likely to attract attention of thieves.

That said I was considering getting the whyte stirling (999), but have seen a 2011 marin mill valley (with the carbon seat stays) on sale at 895, so not sure which to go for.

Blue Meanie

Interestingly, a carbon rear triangle on an alu frame makes the frame heavier!?
Extra lugs and bonding, it's for the perception of 'road buzz' only.
Oh, and it looks cool.

bails87

I'm not suprised adding a small bit of carbon adds weight. Also, the bond is probably the weak part, rather than the carbon itself.

MichaelW

There are several reasons for carbonizing the rear triangle.
You can offer carbon-ish bikes in many sizes without having to make expensive moulds, one for each size.
They may offer better ride.
For commuters, the main dissadvantage is vulnerability to damage from the chain. Sooner or later, your chain will come off and jam between the cogs and chainstay. On steel bikes this is a trivial annoyance. On Alu bikes this may cause some gauging but is not fatal. on carbon bikes, it is an expensive repair or a write off.
There may be riders who have never had a dechain. You can certainly reduce the likelyhood with regular inspection and adjustment. This is tricky for a winter commuter bike, ridden in the dark for 3-4 months in horrible conditions esp if you dont have a nice warm, light workshop.

It may be harder to fit mudguards to a carbon(ized) bike, they usually lack eyelets and rubbing of the 'guard may damage the carbon fibre as much as the mudguard material.

rolf_f

MichaelW wrote:

..... on carbon bikes, it is an expensive repair or a write off.

Ooooh, goody! A "carbon is bad" urban myth I've never heard of before. I am prepared to consider this complete and utter cobblers unless you can back it up with some evidence

Headhuunter

Rolf F wrote:

MichaelW wrote:

..... on carbon bikes, it is an expensive repair or a write off.

Ooooh, goody! A "carbon is bad" urban myth I've never heard of before. I am prepared to consider this complete and utter cobblers unless you can back it up with some evidence

Yes, I've had a full carbon bike since 2007 and the chain has flicked off the front and jammed between the smallest chainring and the frame and also at the back, jamming itself between the cassette and wheel. There has never been any damage to the frame though...

MichaelW

Rolf F wrote:

MichaelW wrote:

..... on carbon bikes, it is an expensive repair or a write off.

Ooooh, goody! A "carbon is bad" urban myth I've never heard of before. I am prepared to consider this complete and utter cobblers unless you can back it up with some evidence

Evidence

rolf_f

Don't know what the hell he did but if he managed to do that much damage to a carbon frame, then I reckon he'd have wrecked a metal frame at the same time. Whatever he did, that isn't a normal chain derailment. You won't hurt a carbon frame any more than a metal frame with a chain off. I've had a few - chipped the paint. That's it.

I can't see that happening on my bikes so maybe this one is down to poor design and that isn't specific to carbon. Can't quite understand though why a little more clearance isn't designed in.

MichaelW

Rolf F wrote:

Don't know what the hell he did but if he managed to do that much damage to a carbon frame, then I reckon he'd have wrecked a metal frame at the same time. Whatever he did, that isn't a normal chain derailment. You won't hurt a carbon frame any more than a metal frame with a chain off. I've had a few - chipped the paint. That's it.

I can't see that happening on my bikes so maybe this one is down to poor design and that isn't specific to carbon. Can't quite understand though why a little more clearance isn't designed in.

A simple chain coming off and resting on the stays isnt going to hurt anything. Its where the chain gets caught between the inner ring and the stay where the gap is very small and there isnt room for a chain, or the chain falls off the small sprocket and winds around rear axle till it jams up the wheel.

snailracer

CarlosDSanchez wrote:

My specialized sirrus elite has them and it's a more comfortable ride than my cube agree which doesn't (run both with 23mm tyres btw)

Certainly feels like it takes some of the road vibrations out of the ride, but they are very different bikes.

I'm not doubting your experience, but I would assign it to factors other than carbon seatstays.
In order to absorb 1mm of vertical bump, simple geometry dictates that the seatstays would have to splay outwards or inwards by about 10mm EACH, which simply does not happen.

Headhuunter

MichaelW wrote:

Rolf F wrote:

Don't know what the hell he did but if he managed to do that much damage to a carbon frame, then I reckon he'd have wrecked a metal frame at the same time. Whatever he did, that isn't a normal chain derailment. You won't hurt a carbon frame any more than a metal frame with a chain off. I've had a few - chipped the paint. That's it.

I can't see that happening on my bikes so maybe this one is down to poor design and that isn't specific to carbon. Can't quite understand though why a little more clearance isn't designed in.

A simple chain coming off and resting on the stays isnt going to hurt anything. Its where the chain gets caught between the inner ring and the stay where the gap is very small and there isnt room for a chain, or the chain falls off the small sprocket and winds around rear axle till it jams up the wheel.

If you just keep your gearing well maintained and properly adjusted, the chain barely ever (if ever at all) comes off, let alone gets completely wrapped around the rear axle like that! I've had the occasional chain drop, it happens once a year or something and I simply stop pedaling as soon as it happens and put the chain back on the cassette, no harm done! I think you're worrying about a non-risk...

snailracer

MichaelW wrote:

Rolf F wrote:

Don't know what the hell he did but if he managed to do that much damage to a carbon frame, then I reckon he'd have wrecked a metal frame at the same time. Whatever he did, that isn't a normal chain derailment. You won't hurt a carbon frame any more than a metal frame with a chain off. I've had a few - chipped the paint. That's it.

I can't see that happening on my bikes so maybe this one is down to poor design and that isn't specific to carbon. Can't quite understand though why a little more clearance isn't designed in.

A simple chain coming off and resting on the stays isnt going to hurt anything. Its where the chain gets caught between the inner ring and the stay where the gap is very small and there isnt room for a chain, or the chain falls off the small sprocket and winds around rear axle till it jams up the wheel.

I don't think its physically possible to wrap chain around the rear axle unless it's a fixed hub. OTOH, it's quite possible for the chain to get wedged between chain stay and chainring, as you describe. However, that's probably off-topic because it damages chain stays, not seat stays which is what the thread is about.

snailracer

Rolf F wrote:

Don't know what the hell he did but if he managed to do that much damage to a carbon frame, then I reckon he'd have wrecked a metal frame at the same time...

Metal frames dent and scratch but tend not to crack.

Rolf F wrote:

...Can't quite understand though why a little more clearance isn't designed in.

AFAICT the chain dropped off the chainwheel and got wedged between chainwheel and chain stay.
This problem is quite common in mountain bikes, where the chainstays have to be wide apart to fit wide tyres, so there is conseqently not much clearance between chainring and chainstay for a given q-factor (pedal-to-pedal spacing). Road bikes have narrow tyres, but the designers still prefer narrow clearances for dubiously small weight savings and aerodynamic benefits of a narrow q-factor.