FAO: EKE and the carbon doubters...

bails87

...No, it's not a 70's disco group!

I can't remember if this has been shared on here before, but it's a comparison of the carbon and aluminium MTB models made by Santa Cruz. 'Destructive testing' I think it's called.

http://www.pinkbike.com/news/santa-cruz ... t-lab.html

Basically, the carbon models were a lot stronger than the aluminium ones, but you'd struggle to break either in the real world. I wonder how well that compares to road bikes?

veronese68

I know, I know. With carbon it's partially that I'm a bit old fashioned, but largely that I can't afford it. So it's easier to stick to mistrust.
Similarly with the lefty fork thing, I know it works and can be made strong enough (like on a car). But I'm not convinced of the advantages or the aesthetics (can't afford that either).

DonDaddyD

I still can't believe there are those that still dispute the strenth of carbon fibre. Probably fly on them aluminium planes when going on holiday...

tailwindhome

Carbon.....never again.

Frame fit pump fell out of place, got pulled into the rear wheel and cracked the seat stay.

<100miles on the clock.

bails87

TailWindHome wrote:

Carbon.....never again.

Frame fit pump fell out of place, got pulled into the rear wheel and cracked the seat stay.

<100miles on the clock.

Sounds like the problem is with whatever was meant to be holding the pump.....


Ouch, though

rick_chasey

Carbon bikes are designed to be strong in designed directions and compliant/not in others - to save weight without compromising performance.

As TWH clearly shows - have a crash / do something that it wasn't designed for it's game over.

Metals, not having that feature, tend to be more resilient to forces applied in ways not designed by the bike-maker.

bails87

Rick Chasey wrote:

Carbon bikes are designed to be strong in designed directions and compliant/not in others - to save weight without compromising performance.

As TWH clearly shows - have a crash / do something that it wasn't designed for it's game over.

Metals, not having that feature, tend to be more resilient to forces applied in ways not designed by the bike-maker.

Hmmm, I'm actually not sure it does "clearly show" that. Would an alu frame have failed there too?

and what about Santa Cruz's "smashing the frame off a concrete block" test?

I'm sure my C456 is tougher than my alu Boardman, whilst weighing less, but then it's an MTB, so built for 'unusual' stresses more than I guess a road bike would be. With kevlar in the downtube to protect against rock strikes, for example. Northwind on the MTB side has talked about crashing his into a concrete pillar, with an impact that he would have expected to break an alu frame, it didn't do a thing to the carbon.

It's up to designers to make the thing tough in the right places, I suppose. They can either build it strong in the usual stress points and get a low weight to grab headlines, or they can make it strong everywhere to cover pump/chainstay interaction, but that adds weight. Still lighter than an alu/steel/ti frame of similar strength, but heavier than it could otherwise be. Hydroforming and butting means that metal tubes are weaker in some points than others anyway.

EKE_38BPM

Rick Chasey wrote:

Carbon bikes are designed to be strong in designed directions and compliant/not in others - to save weight without compromising performance.

As TWH clearly shows - have a crash / do something that it wasn't designed for it's game over.

Metals, not having that feature, tend to be more resilient to forces applied in ways not designed by the bike-maker.

Wot Rick said.

bails87

No convincing some of you luddites

rick_chasey

bails87 wrote:

No convincing some of you luddites

Hey, if I'm a pro and I get given a bike by my team, (or I am properly minted), for sure, given me carbon.

I, however, am an amateur (and judging by strava, a slow one at that), who cycles through lots and lots of traffic.

greg66_tri_v2.0

TailWindHome wrote:

Carbon.....never again.

Frame fit pump fell out of place, got pulled into the rear wheel and cracked the seat stay.

<100miles on the clock.

I thought you were going to try for a repair.

Paul E

EKE_38BPM wrote:

Rick Chasey wrote:

Carbon bikes are designed to be strong in designed directions and compliant/not in others - to save weight without compromising performance.

As TWH clearly shows - have a crash / do something that it wasn't designed for it's game over.

Metals, not having that feature, tend to be more resilient to forces applied in ways not designed by the bike-maker.

Wot Rick said.

Resiliant yes but it would have probably bent it and still screwed the frame up and if still rideable I wouldn't trust it as it would introduce a stress point for fatigue to set in.

bails87

Greg66 wrote:

TailWindHome wrote:

Carbon.....never again.

Frame fit pump fell out of place, got pulled into the rear wheel and cracked the seat stay.

<100miles on the clock.

I thought you were going to try for a repair.

Seemingly catastrophic stuff can apparently be repaired: http://www.carboncyclerepairs.co.uk/rac ... irs_2.html

tailwindhome

My take on Carbon Fibre.

It's for racing.

If the marginal benefits are worth replacing a frame when you crash then go for it.


My next good bike will be a Cannondale CAAD 'whatever'or a nice bit of Titanium

sketchley

Problem for me is the thought that if it only designed to be strong in certain direction, then that same design also had a 75kg rider in mind. At 110kgs the frame is likely to flex in a direction it's not designed too.... Hence metal for me....

EKE_38BPM

Paul E wrote:

EKE_38BPM wrote:

Rick Chasey wrote:

Carbon bikes are designed to be strong in designed directions and compliant/not in others - to save weight without compromising performance.

As TWH clearly shows - have a crash / do something that it wasn't designed for it's game over.

Metals, not having that feature, tend to be more resilient to forces applied in ways not designed by the bike-maker.

Wot Rick said.

Resiliant yes but it would have probably bent it and still screwed the frame up and if still rideable I wouldn't trust it as it would introduce a stress point for fatigue to set in.

Agreed, but it would probably got you home, rather than carbon fibre which just goes and then leaves you stranded.

Look at F1 car wings. They are strong enough for a couple of people to stand on as they are designed to resist vertical loads. But when they are subjected to any lateral loads, they snap off.

Looks like Rick and I are of one mind when it comes to carbon fibre.

bails87

Sketchley wrote:

Problem for me is the thought that if it only designed to be strong in certain direction, then that same design also had a 75kg rider in mind. At 110kgs the frame is likely to flex in a direction it's not designed too.... Hence metal for me....

The same is true for any frame though. Unless it's just amssively overbuilt in every direction. Look at how narrow the Cannondale Synapse seatstays are, they're designed to flex.

sketchley

bails87 wrote:

Sketchley wrote:

Problem for me is the thought that if it only designed to be strong in certain direction, then that same design also had a 75kg rider in mind. At 110kgs the frame is likely to flex in a direction it's not designed too.... Hence metal for me....

The same is true for any frame though. Unless it's just amssively overbuilt in every direction. Look at how narrow the Cannondale Synapse seatstays are, they're designed to flex.

I'm not sure it is, metal doesn't have directional fibres (Happy to be corrected on this).

bails87

Sketchley wrote:

bails87 wrote:

Sketchley wrote:

Problem for me is the thought that if it only designed to be strong in certain direction, then that same design also had a 75kg rider in mind. At 110kgs the frame is likely to flex in a direction it's not designed too.... Hence metal for me....

The same is true for any frame though. Unless it's just amssively overbuilt in every direction. Look at how narrow the Cannondale Synapse seatstays are, they're designed to flex.

I'm not sure it is, metal doesn't have directional fibres (Happy to be corrected on this).

Still, a frame will flex in any direction, and alu frames are designed, like carbon, to flex in one direction but not in another. Mouseover the seatstay there: http://www.cannondale.com/gbr/2012/bike ... ad/synapse

Paul E

I'm lucky to be 75kg then

mattyg2004

All depends on what the bike is designed for.

Carbon is strong very strong.

Take two frames. Carbon and whatever, Weight for weight the carbon will in everyway out perform the other.
The problem is when the Manufacturers try to save weight.

An F1 rear wing doesn't ordinarily need to survive lateral forces But could be made to very easily but with a gain in weight. Thats NOT what the F1 bods are after. They accept a trade off.

rick_chasey

mattyg2004 wrote:

All depends on what the bike is designed for.

Carbon is strong very strong.

Take two frames. Carbon and whatever, Weight for weight the carbon will in everyway out perform the other.
The problem is when the Manufacturers try to save weight.

An F1 rear wing doesn't ordinarily need to survive lateral forces But could be made to very easily but with a gain in weight. Thats NOT what the F1 bods are after. They accept a trade off.

No-one's disputing that.

We're saying that because of the trade off most carbon bikes seem to have, it's not worth it at an amateur/commuting level (for some..)

sketchley

bails87 wrote:

Sketchley wrote:

bails87 wrote:

Sketchley wrote:

Problem for me is the thought that if it only designed to be strong in certain direction, then that same design also had a 75kg rider in mind. At 110kgs the frame is likely to flex in a direction it's not designed too.... Hence metal for me....

The same is true for any frame though. Unless it's just amssively overbuilt in every direction. Look at how narrow the Cannondale Synapse seatstays are, they're designed to flex.

I'm not sure it is, metal doesn't have directional fibres (Happy to be corrected on this).

Still, a frame will flex in any direction, and alu frames are designed, like carbon, to flex in one direction but not in another. Mouseover the seatstay there: http://www.cannondale.com/gbr/2012/bike ... ad/synapse

I don't trust alu either having snapped one frame already.

As for a seatstay I'm sure I've read some stuff about them not necessarily being load baring at all in any direction. See http://lovelybike.blogspot.com/2011/11/ ... -them.html

EKE_38BPM

Once again, Rick has nailed it.

Rick Chasey wrote:

...it's not worth it at an amateur/commuting level (for some..)

If my sponsor was willing to replace my busted frames, I'd ride carbon (probably) but I'm my own sponsor, so I'll give it a miss.

http://www.bustedcarbon.com/
I'm not the only carbon doubter.

rick_chasey

EKE_38BPM wrote:

Once again, Rick has nailed it.

Rick Chasey wrote:

...it's not worth it at an amateur/commuting level (for some..)

If my sponsor was willing to replace my busted frames, I'd ride carbon (probably) but I'm my own sponsor, so I'll give it a miss.

http://www.bustedcarbon.com/
I'm not the only carbon doubter.

Didn't I show you that link a while back? .

meanredspider

Carbon gives a much nicer ride than aluminium which is very hard and unforgiving (my Variado vs my Cayo). And even pretty nasty breaks can be readily fixed. A mate broke his Trek SLS (or whatever the high-end Madone frames are called) by getting a metal post caught in the rear wheel and broke BOTH chainstays. Trek just did a cut-n-shut on the rear triangle - job done for less than the cost of a cheap carbon frame.

Don't confuse F1 tech with this. That stuff is optimised to the absolute limit like every other part of the car. Though it says everything for CF that they can withstand the crashes that they do

notsoblue

Carbon is fine, I've been commuting on the mean, potholed streets of London on a relatively cheap CF frame for a year and a half now and it has faired much better than I have...

Stevo_666

Santa Cruz have just made their latest World Cup downhill bike with a carbon frame and I'm sure a lot of you have seen the sort of beating these bikes get in downhill races. Even yours truly riding like a numpty is perfectly happy to do a bit of downhilling on a bike that has a carbon rear triangle and bars, so i wouldn't give it a second thought on a road/commuter bike :-)

greg66_tri_v2.0

Surely it all depends.

Carbon can be made with very few lay ups or very many. The number and the way in which the fibres cross over will affect overall strength and torsional rigidity. Alu, steel and Ti can be made thin or thick. To that extent I would guess that carbon offers more latitude to build in strength in the particular areas/directions where stress is greatest without having to resort to a "make it thicker" solution.

One thing I've noticed over the last 5 or so years is how many more London commuters there are commuting on carbon.

Paul E

Greg66 wrote:

Surely it all depends.

Carbon can be made with very few lay ups or very many. The number and the way in which the fibres cross over will affect overall strength and torsional rigidity. Alu, steel and Ti can be made thin or thick. To that extent I would guess that carbon offers more latitude to build in strength in the particular areas/directions where stress is greatest without having to resort to a "make it thicker" solution.

One thing I've noticed over the last 5 or so years is how many more London commuters there are commuting on carbon.

My next frame will be for sure

tgotb

I picked up a high-end Madone with a busted head tube, for next to nothing. Frame was damaged in a head-on collision which would probably have trashed any frame. I've nearly finished fixing it, with a few quid's worth of materials, and when it's done it'll be stronger than when it was new. Try doing that with a steel/aluminium frame, especially in your living room!

NB: I didn't actually fix the frame in my living room, for reasons of marital hamony, but when I was a batchelor I used to do that sort of thing all the time...