Iache – of the 1800 ish riders, the first 45 of each qualifer get into the Mega race (total 450 riders), nos 45-90 get into the Promo race, nos 91-135 get into Affinity 1 which is a timed run, not head to head, and the rest are in Affinity 2, like wise timed.
In my qualifier I ended up with a trashed bike after getting baulked by another rider dumping on the brakes going round the second snowfield, so had to ride most of the run sans chain or mech (still overtook 15 odd riders 😀 ), so ended up in Affinity 1 (came 9th).
Oh, and Martyn Brookes is FAR more than an XC whippet. He was leading his qualifier until he woke up near the woodwork bits to find he was in 12th, then in the main race he had the mother of all stacks on the glacier – went down and hit the catch fence at full tilt – tore his front wheel out and had to spend time hunting for it!. All this on a Yeti 4x bike with 75mm of travel (nutter..)! I was struggling to hang on with twice that.