In part 2 of our Hour Record series, Josh, Hottie and Fatty talk about why you can go faster at altitude, even with less oxygen in your lungs...up to a point.

We chat about the magnificently weird (but mostly magnificent) Merckx hour record, and how much further he might have gone if he knew then what we know now.

Finally, we discuss the cyclists (Moser, Obree, Boardman, Indurain, Rominger and more) and bikes that, a dozen years later, broke the Merckx record and launched an hour-record arms race.