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Is a lightweight bike worth the extra expense?

Sun, 19th Dec 2010

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Does owning a lightweight carbon fibre bike cut down your commuting time? Lance Armstrong on a Trek BikeContrary to expectations, a trial carried out by anaesthetist Dr Jeremy Groves from the Chesterfield Royal Hospital in the UK suggests that cyclists should pay more attention to the weight of the rider than the bike!

Writing in the 2010 Christmas edition of the British Medical Journal, the author documents a comparison between the time taken to complete a 43.5 kilometre commute to work using either an older, secondhand steel-framed bicycle bought for 50 and weighing in at  13.5kg, or a new 1000, lightweight 9.5kg carbon-fibre model purchased thanks to a "cycle to work" tax incentive scheme.

Groves compared his performance on each bike over a six month period, determining which bike to use on each day with the toss of a coin. Ultimately, thirty commutes were made on the steel-framed bike and 26 trips on the carbon fibre machine. The journey times were logged with a cycling computer, which  clocked up 1144 kilometres over the course of the study.

Surprisingly, despite costing twenty times the price and weighing thirty per cent less, the carbon fibre bike was no faster than the steel-framed model. The top speed achieved - fifty-eight kilometres per hour - was the same on both bikes, and the average journey times were 1h48m21s and 1h47m48s respectively, although times were longer in the winter (owing to winds, heavier clothing and more cautious cycling on the part of the rider). Moreover, the author reports that the ride afforded by the carbon fibre bike was much less comfortable and the fear of falling off is higher in bad weather, leading to longer journeys.

Most importantly, Groves points out that although the thirty per cent reduction in bicycle weight achieved with a carbon-fibre frame sounds like a lot, this difference narrows to just 4% when the combined mass of the  bike and rider is considered.

"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 reduced cost."



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Only the times you have to carry it up the stairs to your office on the 30Th floor when the elevator was broken. That may be a benefit there, but from what I read of the rider's experience, it may be just for prestige, to own the lightweight machine? An inflated ego would not add weight to a person, would it? maffsolo, Mon, 20th Dec 2010

A carbon fibre cycle may result in a weight advantage when you consider that a normal tubular frame cycle might cost around 200 - 400, whereas a carbon fibre cycle (like this piece of kit) would set you back around 8500. The considerably lighter wallet should make quite a big difference. Whether that would be offset by the inflated ego maffsolo hinted at, I wouldn't like to say. Also, if you had to chain it to some railings, you'd want a pretty heavy gauge chain and padlock, which might rather defeat the object too. Don_1, Tue, 21st Dec 2010

certainly amongst downhill moutain bikers, the greatest amount of surplus weight is attached to their neck...

Mazurka, Tue, 21st Dec 2010

Is the goal to burn the most fat?  Or to have the best riding experience?

I've ridden a classic road bike, a clunker, and a moderate quality mountain bike (sorry, nothing with Carbon Fiber).

A big part of the experience is in the wheels and tires.

The road bike is much more pleasant to ride on any paved surface...  and as mentioned, also nicer to load into vehicles, or carry inside.  Fenders might be a benefit for the winter though.

The benefits of adding carbon over a good alloy bike are likely negligible except for high end racing.  Perhaps one's money is best spent on a 20 yr old alloy road bike.

CliffordK, Tue, 21st Dec 2010

It's a problem of diminishing returns. Even if you could reduce the mass of the bike to zero, it's not going to make an awful lot of difference to the effort you have to put in to propel yourself. It's still going to be hard work because of hills and wind resistance.

In my case, I'd probably invest the money in a battery power assist system  Geezer, Tue, 21st Dec 2010

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