I called a friend of mine yesterday and he answered breathlessly, panting and puffing as he hurried to tell me about his latest physical feat. ‘Yeah, I (puff-puff) just rode my gym-bike 100km (wheeze)’, he said. Feigning interest, I asked him how he figured that he had gone so far, while technically remaining in one place.
‘Well’, he huffed, ‘I have a pedal counter, and it tells me that for 100 revolutions of the pedals I travel 500 meters. So, as soon as I reached 20,000 I knew I’d gone 100km. Simple.’ That all sounded a bit too simple for me. ‘What about the force is that you are applying to the pedals, and the resistance that the bike is giving you?’ I replied. ‘Doesn’t it also depend on what gear your ride in, the terrain and the size of the crank and tyres on your bike?’
‘No!’ He countered rather angrily – and though out of breath had ago at me for doubting what the latest gizmo on his handlebars was telling in in capital LCD display. 100km! The line went dead.
And that little episode got me thinking about the professional and amateur cyclists all over the world pedalling bikes for commuting, fun and fitness or for medals and prize money and how many times they make the pedals go 360°. So I plugged myself in to an online fitness blog and asked the question to the experts. Here’s the best summary of what I found out:
A stationary bike can only give you a rough estimate of how far you might have gone on a real bike for a similar effort. This includes assumptions regarding your weight, gear length, wheel size, and how aerodynamic you might be in your riding position. It also can’t account for wind resistance (which increases as the square of your speed when you actually move), road gradient, or drive train efficiency.
A standard road bike using 700c wheels, 25c tyres, and a compact crankset (50:34 chain rings, 11:28 sprockets) has a development range of between 2.6m and 9.6m per crank revolution. I think I like the sound of travelling nearly 10m with one turn of the pedals.
So I called my angry-stationary-cycling friend back the following day to apologise for upsetting him on his magnificent feat of athleticism. ‘You’ve got to set yourself a new distance target now,’ I suggested.
‘Nah’, he responded. ‘I’ve gone off the cycling now. I’ve bought a stationary mountain climbing machine. On Saturday I’m going to have a go at Mount Everest. Wish me luck.’