Good lord. It's on the way to 100 degrees today, which would seem to be a perfect occasion to give in and take the climate-controlled subway to work. And yet, I rode. And it wasn't bad at all. Here's an incomplete list of tips for biking in ridiculous heat.
First of all, leave early. I have a day job, more or less, so I leave my house about 8:15am and arrive around 8:45. This morning, I left closer to 7:45, knocking a half-hour of sunlight energy from the day's heat. It's the morning commute you need to stay cool on. In the PM, I know a change of clothes and a shower awaits, so who cares about staying cool?
Second of all, start cool. I took a cool shower and stayed close to our little AC unit while getting dressed, so my core temp was as low as possible before leaving the house. This gave me about a 10 minute jump on the real heat, which is a good chunk of my 35 minute commute.
Next, GO SLOW. I've already written that commuting is not racing, and that goes double for crazy hot days. Strangely, it takes practice to go slow. You need to know your body and your route well, and lay off the gas twice as much as you think you need to. The only "hill" in my route is the Manhattan Bridge at about the halfway mark, and if I can stay cool (read: dead slow) while climbing it, I'm in pretty good shape. If I try to keep up with some punk on a fixie, I'm screwed. If, like me, you get competitive when people pass you, just try to turn it into a game in your head: "if I sweat less than you I win". I was in my granny gear this morning going up at about 5 mph. Leave early, relax, enjoy the view.
Then, find shade! I pay a lot of attention to where the sun is, and try to ride on the side where it's not. In the city, frequently the middle of the intersection is in blinding sun, but there's shade a couple of car lengths back. I found myself stopping well before certain intersections today, in some cases forty or fifty feet before the light, just so I could stand for a moment under the shade of a house or a single tree.
Avoid the backs of buses. They throw off a ton of heat in about a 10 foot radius. If you try to draft trucks and buses to save a bit of effort on most days, drop that habit when the mercury gets above 85.
In addition, all the normal stay cool things apply: drink lots of fluids, wear light fabrics in light colors, and for god's sake, pull over if you think you're gonna pass out.
