Today I was pushing what I could manage. My wife set off for work while I set off for another town 35 miles away to pick up a couple of bits, and then came back.

Including the time I spent at the shop (which wasn't a whole lot), I covered 70 miles in 4 hours and 10 minutes. Taking out the time at the shop that probably drops to more like 4 hours, maybe 3:50. But let's run with 4:10 because I don't want to overstate stuff.

Using bikecalculator.com I entered my details - my weight of 240, I guess the bike weighs about 20, riding the hoods using clinchers, I set the gradient to 0 because although it undulated a little there were no particularly nasty climbs (the total ascent worked out something like 20 feet per mile), and the headwind to 8mph - I had something of a headwind both ways, the forecast said force 3-4, so I assumed a constant value that seemed reasonable.

According to the results it gave me I was putting out 271 watts for four hours, burning 3886 calories in the process. I find those figures surprising, I usually figure about 40 calories per mile which would land me more like 2800 calories. If I factor out the time I spent in the shop buying my stuff and drop the time to 3:50 then the power goes to 315 watts, and if I drop the headwind to 5mph it shows 257 watts for four hours.

Do these figures seem reasonable - have I got stronger than I realised?