Doctor claims carbon offers no benefit over steel
Spending more won't get you there any quicker, says new research
Cyclists considering upgrading their bike to a new, lighter frame to boost their speed in 2011 might be better off giving the mince pies and trifle a miss this Christmas, according to new research published in the British Medical Journal (BMJ).
The study was carried out by hospital consultant Jeremy Graves, who specialises in anaesthetics and intensive care, and who conducted the research using a sample of just one – himself. Not the most scientifically robust sample, admittedly, but it does mean that in terms of the cyclist at least, like is being compared with like.
Mr Graves, who lives in Sheffield and works in Chesterfield, does his 27-mile round-trip commute by bike most days, and after six months of commuting on a £50 steel-framed bike, was tempted by the thought, according to “those in the know,” that he could knock 10% off his 55 minute one-way trip time by switching to a new carbon frame.
The consultant bought his new, £950 bike through the Cycle to Work scheme, and says: “My new bike seemed wonderful, if somewhat uncomfortable. I didn’t notice a dramatic decrease in commuting time, nor did the cycle computer I had fitted to my new bicycle to record any notably swift journeys. But, one sunny morning, I got to work in 43 minutes, the fastest I could recall.”
So far, so good. But then, after suffering a puncture, Mr Graves retrieved his old steel-framed bike from the corner of the garage to which it had been consigned – there’s no explanation for why he didn’t fix the flat on his new bike – and made a surprising discovery; his commute took 44 minutes.
He asked himself, “Hang on, was that minute worth £950 or was it a fluke?” and says “there was only one answer: a randomised trial.”
Accordingly, between January and July this year, he determined which of his two bikes he would ride to work on a particular day by tossing a coin, recording details of the ride through a Sigma bike computer.
The result was that he made 30 journeys on the steel-framed bike, and 26 on the carbon one during the six-month period. “The top speed achieved was 36 mph (58 kph) on both bicycles,” he says.
“The slowest journey [for the round trip] was on the carbon bike in heavy snow (2:03:20). The fastest journey was on the steel bike (1:37:40) and was as a direct result of chasing one of my fitter cycling colleagues to work.
“The average journey time on the steel frame bicycle was 1:47:48, and the average journey time on the carbon frame bicycle was 1:48:21. The difference in the mean journey time was 00:00:32.”
Mr Graves says that the difference in commuting times between the two bikes was negligible because, although the carbon-framed bike was 30% lighter than the steel one, the reduction in total weight (including the rider) was just 4%. Such a minor difference, he says, had little effect on some of the forces acting against the cyclist, such as rolling resistance and acceleration, and none at all on others, such as drag and traffic.
So what does it all mean? Mr Graves concludes, “A new lightweight bicycle may have many attractions, but if the bicycle is used to commute, a reduction in the weight of the cyclist rather than that of the bicycle may deliver greater benefit and at a reduced cost.”
We knew that already, didn’t we? Although the fact that there was absolutely no decrease in travel time on the carbon bike may be more of a surprise to many.
Mr Graves reckons so many of us spend our cash on lightweight bikes largely because of marketing. Referring to the medical profession he says, “Many of us respond to ‘new’ pharmaceuticals in a similar way to how cyclists respond to ‘new’ bicycles.
"The industry invests significantly in marketing products of marginal benefit and we, as medical consumers, frequently buy into the panacea rather than objectively considering the evidence. We must excuse consumerism, particularly at this time of year, because without it our capitalist society would collapse.”
Although buying the carbon bike made Mr Graves feel good and he still sometimes uses it for commuting, he enjoys riding the steel bike more. And if the carbon bike were stolen, would he replace it? “I’d have to say no. I’d spend the money on high visibility low drag clothing and better lights.”
To be fair to Mr Groves, his study is very lighthearted, and it’s included in the Christmas edition of the BMJ where those fun-loving medics like to go a bit madcap and ker-azy. He does, for example, say that he considered turning his randomised trial into a blind study, “But in the interest of self preservation and other road users, decided against it.”
There are a couple of things relating to Mr Graves’ research that we reckon are worth emphasising though. First, this all refers to one man's commute. We can’t see many cash-strapped racers doing too well on a 30lb road bike. We could be wrong.
Second, if that new, shiny bike you’ve just bought encourages you to get out and put more miles in, you’re going to lose weight anyway, making the purchase a win-win from both points of view.
To view the full BMJ article go to www.bmj.com/content/341/bmj.c6801.full.