The obvious first First Alternate choice is your other riding buddy who kinda wanted to go but didn't really think he could afford it, or get the time off work, or have enough time to train (despite the fact he's on EVERY ONE of your rides), but would be powerless to resist being a hero if called upon in the final hour. I was basically this guy my first season. The hook is simple: You hand him a pint and the chance to join you on a huge testosterone-fueled competitive adventure with the excuse (for wife/girlfriend/mom/boss) that he has to do it because his buddy is in a pinch and has nobody to turn to... He's in for sure.
But if he bails too (SOME FRIEND YOU ARE!) don't forget about your other best friend:
Sure, he doesn't ride a bike, but he's way faster than you on the singletrack and always has a spare wet-nap for your shades. Loyalty is his middle name, and he never complains about the fare at aid stations:
Your four legged friend might even be a ringer. In Transrockies 2006, Rufus, the camp dog from Nipika, ran the entire 64k to invermere and came in 136th overall (of 175). Sure, that's not a podium spot, but he was RUNNING, and probably stopped to pee on at least 300 trees.
I took my second alternate out for a ride today in some "choice" conditions to test him out against the studded tires from my last post. It was 24degF and snowing with a trail surface that was about 60-70% clear and 30-40% glare ice, all blanketed with about 3/4" of fluffy white on top. The tires do grip a little better at speed than doggie claws, but in the rough stuff I didn't have a chance against a quadriped.
Glare ice + about an inch of snow tends to be the most difficult terrain for a studded tire because the snow packs between the studs and the ice then slides. As a designer, you're always working a compromise between more rubber for better dry traction or deep snow shoveling and less for better spike bite. Schwalbe erred all the way in the bite direction with with tall, narrow-headed knobs and lots of open space (click pic for big). Not surprisingly, the Schwalbe performed very well today, somewhat justifying the compromise on deep-snow traction. This is truly an ice tire (good thing I live in New England). As expected, it didn't grip particularly well on exposed rocks, of which we have many at the moment, but the grip was consistent and when it slid, it did so predicatably. Eric has a pair of Nokians in the mail, so we'll be pitting them head-to-head with my setup if the (crappy) weather holds.
Ride safe. Ride in the woods.