Doctor claims carbon offers no benefit over steel

Spending more won't get you there any quicker, says new research

by Simon_MacMichael   December 10, 2010  

Look 585 - riding 4

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.

 

29 user comments

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Hang on...

"although the carbon-framed bike was 30% lighter than the steel one, the reduction in total weight (including the rider) was just 4%"

Even though he was choosing his bike randomly between days? What extra ballast was he carrying to make up the 22%?

posted by mclarent [6 posts]
10th December 2010 - 17:16

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himself - the carbon bike was 30% lighter than the steel, but as his weight remained the same (and made up the majority of the total weight) the total weight was only 4% difference.

i find it doesn't matter which of my bikes I ride on the commute, it usually takes around the same time. But that's because the major factor affecting my times is traffic, and traffic lights. Whereas on a ride around the park, or out in to the countryside, the difference is noticeable in times over the same route.

posted by step-hent [644 posts]
10th December 2010 - 17:24

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This article has not helped my n+1 (where 1 is carbon or titanium) cause with my wife… Damn you BMJ Crying

Pete Bragg
Shutt Velo Rapide
www.shuttvr.com

Miggers's picture

posted by Miggers [63 posts]
10th December 2010 - 18:34

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No need for tears Miggers step-hent has just played the get out of jail card. I was thinking exactly the same thing about my commute, the time varies a bit as I get fitter on sections of it like hills, but overall traffic lights, traffic all conspire to slow you back down again.

Tony Farrelly's picture

posted by Tony Farrelly [4131 posts]
10th December 2010 - 18:49

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Looking back at some figures from 2009, I'd say my SCR 2 road bike averaged just over 31mins for the commute home while the 12 year old Kona MTB (rigid w/slicks) averaged high 33s. There was a difference of 2 minutes on the morning commute over the same route (10 lumpy miles along Shropshire B-roads and lanes). Weather was usually better and warmer when on the SCR than on the 'hack' bike.

Simon E's picture

posted by Simon E [1888 posts]
10th December 2010 - 18:58

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"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.”

that's one of the most sensible reports i've read in a while! and cervelo have done a lot of work to prove that reducing drag has a greater effect on our speed than reducing weight. i get asked about bike weights all the time, but never aerodynamics, thankfully!

posted by james-o [188 posts]
10th December 2010 - 19:33

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tony_farrelly wrote:
No need for tears Miggers step-hent has just played the get out of jail card. I was thinking exactly the same thing about my commute, the time varies a bit as I get fitter on sections of it like hills, but overall traffic lights, traffic all conspire to slow you back down again.

Thanks Tony/step-hent - I will print off for Mrs Miggers!

Pete Bragg
Shutt Velo Rapide
www.shuttvr.com

Miggers's picture

posted by Miggers [63 posts]
10th December 2010 - 19:42

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I lose the most time when riding or training at traffic lights, so this really isn't a very scientific study. 44 minutes for 13 miles between Sheffield and Chesterfield isn't to be sniffed as it's hilly round there (unlike where I live). So for someone who rides fast already (compared to most of the population) he isn't going to see much improvement with a carbon bike.

If cycling is indeed a sport of self-abuse why aren't more cyclists sectioned under the mental health act?

posted by hairyairey [275 posts]
10th December 2010 - 21:00

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This research is fundamentally flawed. It takes absolutely no account of my need for new toys...

posted by Chrisc [138 posts]
10th December 2010 - 21:12

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sad but true;
Wife bought me new CAAD9 because I was cycling so much, but the old Giant ALU hardtail (40 bob from a recycling scheme) still gets far more regular use; school run, shopping,library.
The CAAD flies, urging me on, but I'm so nervous of it getting damaged or pinched! I'm totally relaxed on the hardtail, throw it around, jump over gutters, lock it up, do my thing.

"Inside every car is a pedestrian, just Waiting to get out..." S.J.L.

scotter's picture

posted by scotter [64 posts]
10th December 2010 - 22:02

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Body weight and fitness are the two prime factors in increasing speed. So long as the bike is comfortable and efficient to ride, times will come down.

The next issue having achieved a good weight and level of fitness is achieving average speeds above 20, 25 and then the magic 30mph. At these levels of speed fitness and body weight tail off as wind resistance takes over as one will be thwarted by an invisible barrier whether the bike is made from carbon or lead. The material the bike is made from is irrelevant.

I agree with the Doctor but I also agree with the above comment - there's just no room in this research for new toys.

posted by 5339 [21 posts]
10th December 2010 - 22:07

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Alternative Heading;
"Doctor speaks out his arse!"
Devil

"Inside every car is a pedestrian, just Waiting to get out..." S.J.L.

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posted by scotter [64 posts]
10th December 2010 - 22:08

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I remember chasing other riders on my commute across London. i was on my heavy steel mountain bike and they were on lightweight racers and a lot of the time I'd still get past. I was younger then.

OldRidgeback

posted by OldRidgeback [2114 posts]
10th December 2010 - 22:28

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My journey, irrespective of bicycle manufacturing material is always faster when the end result is cake and coffee!

The_Kaner
FREEEEEEEEDOM!

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posted by The _Kaner [375 posts]
10th December 2010 - 23:22

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Well I dont think this research applys to the population that I am interested in, currently I have a £1k bike made of aluminium but I want to buy a £3.5k carbon bike therefore the quality will be 3.5x better than the bike involved in this sample and therefore the results do not apply.

Serioulsy though, 1k for a carbon bike, everything is surly going to be a bit ropey and the frame wont be that good either, a much better choice would have been a really good alu bike and probably faster.

posted by miffed [163 posts]
11th December 2010 - 1:08

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I'm stunned the BMJ would even print such trollup!

Scientific? I'd be thrown of my A'levels/undergraduate degree with methodology of research lol

I like my bike but it needs a hidden 25cc motor Smile

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posted by Fish_n_Chips [325 posts]
11th December 2010 - 2:11

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It's an interesting article, but he *does* make the point that this is a commmute. I find my commute takes the same time whether on my steel tourer complete with panniers or my light alu racer with just a bottle of water. But I wouldn't do a triathlon on my tourer (not least because I'd probably be laughed out of transition!!!) So the rider's weight is going to be critical. Lance Armstrong in his autobiography said that he was advised to lose weight when he started doing the Tour and I belive there's a forumula for the ideal power to weight ratio. Happily the best way to lose weight (I find) is to go cycling...

posted by RuthF28 [87 posts]
11th December 2010 - 9:23

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@fish_n_chips The BMJ is a bit of a headline grabbing rag, and like the Lancet is the equivalent of a red top (at best). Not well respected in the scale of medical journals. The Christmas edition usually has a number of tongue in cheek pseudo scientific studies, all harmless, but often of better quaity than the more regular articles!

posted by richardvaltos [18 posts]
11th December 2010 - 10:00

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There's no easy win, is there? My 'top end bike' (a very average Trek 1400) is without doubt quicker and leaves me less tired. It's easier up hill but slower down). On the contrary my aggregate of of bits and pieces clumped on to a 25 year old road frame is heavier (especially up hill), but it does cruise nicely over Oxfordshire's battered and neglected roads and cycle paths and means I don't have double vision for 80% of the commute.

To wit: leave the mince pies alone this Christmas Wink

posted by carl j [23 posts]
11th December 2010 - 11:03

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Yes clearly a commute is going to be determined by factors such as traffic and lights.

However I can offer proof that carbon is faster than steel.

Pretty much all my riding is training, and I use the same route three or four times a week. It has virtually no interruptions or variables, and I set my computer to pause below 20km/h anyway for the few times I do slow down.
Once a week I ride with a group so there is less control but generally we also ride the same route and pace each week.

Until July I was riding a steel Colnago Master with 10sp Chorus and Racing 5 wheels,and my average speed was 34.57 km/h .

From August I have been riding a carbon Ridley Noah with 11sp SR and Eurus or Racing 3 wheels and my average is 35.66.

So the extra speed costs about £600 per .1 km/h.

Whether that helps in the n+1 debate is another thing.

abudhabiChris's picture

posted by abudhabiChris [494 posts]
11th December 2010 - 14:33

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abudhabiChris wrote:
Until July I was riding a steel Colnago Master with 10sp Chorus and Racing 5 wheels, and my average speed was 34.57 km/h. From August I have been riding a carbon Ridley Noah with 11sp SR and Eurus or Racing 3 wheels and my average is 35.66.

Have you been back on the Colnago Chris? Maybe with the new bike you've been pushing harder and got fitter too. New bar tape makes me go faster. Seems to anyway Wink

I think the subject of upgrades, saving grams, and deliberating between materials and choosing deep or shallows rims is all quite fascinating. The fact that this all appears so difficult to quantify all adds to the fun!

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posted by simonmb [360 posts]
11th December 2010 - 16:15

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Any bloke gullible enough to think there's a possibility a different bike will knock 10% off his commuting time – a proportion of which he's stationary at traffic lights – deserves to be a grand down.

Just nipping round to sell him a few tins of tartan paint.

posted by Mat Brett [1808 posts]
12th December 2010 - 10:43

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@simonmb
Well there is certainly a fear factor - having spent all that money on a bike I feel I should have something to show for it.

However I do also ride a fixed gear regularly, which has been across the Colnago and the Ridley. Unfortunately the logging site I use doesn't allow me to extract data by bike but I am pretty sure I am riding at much the same speed on the fixie in both periods.

It used to be about the same or a little higher than the Colnago but is now a little slower.

Look, let's just agree that you all need Ridleys. Tell your partners/bank managers/bosses I said so.

abudhabiChris's picture

posted by abudhabiChris [494 posts]
12th December 2010 - 18:03

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abudhabiChris wrote:
@simonmb

It used to be about the same or a little higher than the Colnago but is now a little slower.

Interesting comments Chris. What is the weight difference between the Ridley and the Colnago?

I have an old Colnago Master that I've been spending the winter busily buying lightweight bling for as currently its 10kg. However now I wonder if its worth it. I guess your comparisons are on relatively flat terrain if you're also riding fixed?

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posted by TheHatter [810 posts]
12th December 2010 - 20:08

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Dr. Duh - you don't need an expensive bike to ride 15 mph

posted by chickeee [12 posts]
12th December 2010 - 21:33

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chickeee wrote:
Dr. Duh - you don't need an expensive bike to ride 15 mph

Missed the point chickeee, if you have an expensive bike then you ride at 15mph so everyone can see you have one. Wink

Did Nightrider 2013 for Parkinson's UK, doing it again this year just for the fun of it and to raise more money.

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posted by jova54 [583 posts]
12th December 2010 - 22:09

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Do you know I've never weighed the Colnago - never seemed much point to me weighing a steel bike. Wink I'm not particularly weight-obsessive anyway.

The Ridley should be around 7kg with the Eurus wheels, maybe a touch more. The frame starts at 1.2kg.

It's enough difference that I notice I get blown around more easily by trucks (we ride a lot on the hard shoulder of a highway) on the Ridley than the Colnago.

And yes, totally flat - I can ride 140km and have about 250m of climbing.

abudhabiChris's picture

posted by abudhabiChris [494 posts]
13th December 2010 - 9:18

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I wish I never weighed my colnago. Now I might have reduced the weight a little but my wallet is a lot lighter!

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posted by TheHatter [810 posts]
13th December 2010 - 20:51

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Well, I ride a Cannondale CAAD2 alloy racer (old but nice) and a Claud Butler steel tourer (even older and retro-nice). The Cannondale is a little under 30% lighter, and I do the same training runs on both (depending on weather and mood). I do go faster on the Cannondale, but this is due I think mostly to psychological reasons: it "feels" faster (geometry, handling, etc.), I'm more likely to chase down blokes on mountain bikes, and also the gearing is higher. But the only time I really notice the weight difference is when I have to lift the bikes back into the shed!

posted by nedr [5 posts]
14th December 2010 - 23:56

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