Fear of carbon

[[XAP]Bob]

I *think* Brucey and I are amongst the most vociferous "CF failure mode is often inappropriate" people on this forum.

Yet neither of us ever say that CF is a bad material, or can't be used to build a good bike.

The question is always one of cost/benefit analysis, where neither cost nor benefit can necessarily be measured in sterling.

Benefit from CF:
- Lightweight for given strength (very small delta in complete vehicle system, particularly if UCI restricted)
- ???

Costs of CF:
- Brittle failure modes
- Relatively easy to damage with "non designed" stresses (drop injury, bidons ripping out, hit whilst parked)
- Tend to be less luggage capacity (this is a design decision though)


For a racer then the costs can be mitigated and the benefit is potentially significant.
For a "Sunday best" the costs can be mitigated, but the benefit is incredibly small - but this is hobby territory, so perception is a benefit.
For a commuter the costs are hard to mitigate, the benefit is almost certainly negligible.
For a loaded tourist the costs are high and the benefit is non existent.

Given that the failure mode is more often "warningless" than on other materials the brittle failure mode is an unacceptable risk (to me) when in heavy traffic, particularly if the following vehicle might be a bus...

CF isn't bad, CF isn't going to explode as soon as you look at it. Noone makes that claim.
CF is however susceptible to failure modes which are sudden and nasty, by various mechanisms, almost none of which apply (or have equivalents) in the world of steel or other metals.

[hamster]

If it isn't an Olympic year, the economy is a bit iffy, and people are put off international air travel (crashes, terrorism, Ebola, etc) then I'd guess that CF is not in such high demand and will be cheap for a while.

The orderbooks for aircraft are somewhat longer, beyond the typical 3 year economic cycle. Airbus and Beoung have orderbooks of over 1000 aircraft.
Automotive is also becoming a major consumer of carbon fibre, we are on the tipping point where it jumps from racing and specialist vehicles to mass-production. The electric BMW range use significant quantities of the stuff. This will transform the economics in the same way that the fall of the Soviet Union made lots of titanium available.

[maxcherry]

How does a person know that they have a good carbon bike?
Say if a person spent £700 on a full carbon bike, would that be as good as a £1000 bike

What about forks. If a person spent £700 on a alu bike with carbon forks, would the forks
be bog standard forks or quality forks?

Reading this thread and everyone's views and experiences, it's still not clear.

I understand that most frames are mass produced and the bike company sticks a logo on
and chooses a price, depending on brand name and spec, the price can go up or down.

So how does the average woman/man know that they have a good CF frame or not.

[pliptrot]

I very much doubt that there is much correlation between price and quality (however that is measured). The marketing men long ago figured out how to break the link between a high price and value. True, you can only get what you pay for. But -judging by the retail prices of so much of the output of the cycle industry- you are highly unlikely to get that, either. What - 10 years ago - bought the top-of-the-range-tour winning complete team replica bike now will not even stretch to their best frame. I guess their marketing team figured out that mamils are often going through a mid-life crisis, and priced their offerings accordingly.

[Brucey]

...So how does the average woman/man know that they have a good CF frame or not.

it isn't clear. But a good guide is the warranty that you get.

However you should check online to see how the various companies are honouring their warranties at present; in recent times some warranties that used to be very good (eg Trek's) have reputedly become less reliable and less easy to implement.

...we are on the tipping point where it jumps from racing and specialist vehicles to mass-production. The electric BMW range use significant quantities of the stuff. This will transform the economics in the same way that the fall of the Soviet Union made lots of titanium available.

agreed. But the most recent info that I have (which is not that recent but then I have not been looking that hard) talks of current and near future oversupply of both CF and large CF airframes (orderbooks can be meaningless depending on the get-out clauses). There is talk of a price war between Boeing and Airbus, and airlines are speaking of placing orders for their new aircraft at about 1/3 list price....

In automotive the 'barrier' price has long been held to be around $5/lb for more widespread adoption of CF. The price has been dropping for a while but I don't think we are quite there yet...

cheers

[tim-b]

Hi

I'm not so sure about warranty length as a guide. Hyundai and Kia share R and D facilities, engines, basic bodyshells, etc (http://online.wsj.com/articles/kia-struggles-as-sibling-hyundai-speeds-ahead-1409208932)
Hyundai offer a 5-year warranty and five years roadside assistance and Kia a 7-year warranty and roadside assistance for 1 year

My 2p-worth, see what other people ride and have a chat. I think that the established companies have a valuable reputation to lose if they sell anything that doesn't perform

My current Sunday-best is a Sensa, made by Intersens Bikes & Parts BV, a Dutch company established for over 25 years. Merlin Cycles sell them in the UK, excellent service and a good price http://www.merlincycles.com/sensa-bikes-57810/?filterBrand=216

Regards
tim-b

[pliptrot]

I think that the established companies have a valuable reputation to lose if they sell anything that doesn't perform

In this highly specialized marketplace, I think of a few established companies who have thumbed their noses at customers with problems; inluding one who sent a customer a tube of loctite to glue the loose push-fit bottom bracket cups into a frame which cost him more than his gross income for a month. A professional backside on the bike counts for far more than making customers happy, it seems.