What do you least want when you’re cycling in the rain across a barren moor, and have just climbed up to about 350m? Answer, to stop for several minutes at traffic lights! Just long enough so that you stop generating all that lovely heat. Just long enough for the wind to start chilling your soaking wet rain gear. And just long enough that blood in your extremeties gets a bit chilled, so that when you start pedalling again, you sent a cold chill into your core. No other options except to crank a big gear hard until you get some heat going again.