CHRISTMAS 2010: THE LIVES OF DOCTORS Bicycle weight and commuting time: randomised trial

Objective To determine whether the author’s 20.9 lb (9.5 kg) carbon frame bicycle reduced commuting time compared with his 29.75 lb (13.5 kg) steel frame bicycle. Design Randomised trial. Setting Sheffield and Chesterfield, United Kingdom, between mid-January 2010 and mid-July 2010. ParticipantsOneconsultant inanaesthesiaand intensivecare. Main outcome measure Total time to complete the 27 mile (43.5 kilometre) journey from Sheffield to Chesterfield Royal Hospital and back. Results The total distance travelled on the steel frame bicycle during the study period was 809 miles (1302 km) and on the carbon frame bicycle was 711 miles (1144 km). The difference in the mean journey time between the steel and carbon bicycles was 00:00:32 (hr:min:sec; 95% CI –00:03:34 to 00:02:30; P=0.72). Conclusions A lighter bicycle did not lead to a detectable difference in commuting time. Cyclists may find it more cost effective to reduce their own weight rather than to purchase a lighter bicycle. INTRODUCTION I have always been keen on cycling. As a child in the 1970s, a student in the 1980s, and a junior doctor in the 1990s, my prime means of local transport was a bicycle. An accident, shortly after taking up a registrar job in Sheffield, wrote offmy bike and ledme to turn to the internal combustion engine.However, after a number of years as a consultant, peer pressure and the desire to improve my fitness led to a decision to return to the saddle. I acquired a second hand steel frame bike for £50, spruced it up, and set off. I soon got into the swing of cycling the 27 miles (43.5 kilometres) from home in Sheffield, United Kingdom, to work in Chesterfield and back, managing it most days when I wasn’t on call and didn’t have commitments off site. After about six months of commuting I began to wonder whether the one way journey time of about 55 minutes could be reduced. Those in the know suggested a new bike could knock 10% off it. Evidence based cycling is not high on the bicycle salesman’s agenda. No one will tell you how much more efficient one bicycle is over another; they just say it is better. Making a decision on what was perceived to be best and dreaming of extra time in bed, I looked into the UK government’s Cycle to Work scheme.This schemeallows an employee to purchase a bicycle (up to a cost of £1000 (€1180;$1560)) at a significant discount by using tax incentives, provided the bicycle is used for commuting to and from work. The initiative aims to “promote healthier journeys to work and reduce environmental pollution.” However, doubt has been expressed in the popular press regarding whether the new generation of middle aged men in lycra (MAMILs) are actually using their scheme funded bikes to commute or just to gum up the roads (particularly hills) at weekends. The benefits are debatable but attractive, and the scheme has encouraged a lot of people to spend a lot of money on high end bicycles. I purchased a bike at the top end of the cost allowed by the scheme and opted for a carbon frame because it was significantly lighter than my existing bicycle’s steel frame. The wheels were lighter and tyres narrower too. All were factors that made me believe that the extra £950 I had spent would get me to work in a trice. Mynewbike seemedwonderful, 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. My steel bike was consigned to a corner of the garage to gather dust—until I had a puncture. The next day I was back on my old steel bike. I fitted the cycle computer, set off . . . anddiscovered I had got to work in 44 minutes. “Hang on,” I thought, “was that minute worth £950 or was it a fluke?” There was only one answer: a randomised trial. I toyed with the idea of blinding it but, in the interest of self preservation and other road users, decided against it. METHODS This was a single centre, randomised, non-blinded trial; n=1. Both bicycles were of traditional “road” construction with drop handlebars, although the frame of one was made of steel and the second carbon (table 1; fig 1). Identical lights and fittingswere usedon eachbike. Between mid-January 2010 and mid-July 2010, either the steel frame bicycle (29.75 lb (13.5 kg)) or the carbon bicycle (20.9 lb (9.5 kg)) was randomly Department of Anaesthetics, Chesterfield Royal Hospital, Calow, Chesterfield, UK Correspondence to: J Groves [email protected] Cite this as: BMJ 2010;341:c6801 doi:10.1136/bmj.c6801 BMJ | ONLINE FIRST | bmj.com page 1 of 4 allocated formydaily commute according to the toss of a £1 coin. The time the bicycle was moving for the 27 mile (43.5 km) round trip was recorded with a Sigma BC906 bicycle computer. The clothing worn was determined by the weather conditions on the morning of travel. Water was not carried. The journey, predominantly on urban A roads, included 0.62 miles (1 km) of dual carriageway, 1.86 miles (3 km) of country lanes, and 328 feet (100metres) of farm track. The total ascent for the round trip was 2766 feet (843 metres; fig 2). The journey times were entered into Calc, a spreadsheet in the Open Office Suite. Times were compared using a two tailed Student’s t test.