A typical Christmas dinner with trimmings packs 956 calories, according to the British Nutrition Foundation. Add cake (249 calories), pudding (587), a pint (185), two mince pies with cream (368 x 2), and a few glasses of wine (87 x n), and you can see why many people’s New Year Resolution is to get that flat-tyred bike out of the garage.
The level four miles from my house to King's Cross uses 68 calories, according to my odometer’s arbitrary-looking figure. At that rate, I’d have to cycle 175 miles to burn off my mum’s Christmas lunch.
So it’s just as well there are lots of other reasons for cycling today or over the next week, and not just cancelling out a surfeit of plum duff. Going out for a spin is the perfect antidote to yuletide ennui: those gaping holes between the Queen's speech and the blockbuster film, or Boxing Day and New Year, that can't be plugged with nuts and sherry.
It's also an experience in itself. Roads feel better, with virtually no lorries and only a few family cars doing the rounds. In cities, the absence of buses on Christmas and Boxing Day (whenever that is this year) makes the streets blissfully quiet – but the street cleaners are off too, so watch out for broken glass. Railways are at a standstill, as may you be after that dinner, so keep distances modest (no sag-wagon train back). Daylight's short (8am-4pm in London, only 9am-3.30pm in Inverness) so make the most of it.
Pubs are usually open at Christmas lunchtime but not evening; finding an open cafe or eatery will be tricky, so phone before to check. If you live near an ethnic area where today is another working day, enjoy the difference and try a new restaurant.
Any present is an excuse for a ride: why not test-drive that new pair of socks? Do your family-and-friends visits on two wheels – no risk of drink-driving.
Everyone's friendly. Ambling round on Christmas morning you'll be greeted cheerily by dads in new sweaters and kids taking their new fifty-quid mountain bikes round the block for the first (and probably last) time.
If you have a White Christmas, a bike is the best way to enjoy countryside whiteouts, or your town wrapped in cotton wool.
So enjoy that seasonal spirit from the saddle, and earn your rosy cheeks from fresh air rather than the sherry. Then if you do indulge, at least you have an excuse. You might even have worked off a few calories.
(This is updated text from an article I wrote for the CTC magazine in December 2007. Other bits of the article were posted yesterday.)