Most estimates say that the wind trainer is about 20% harder than being outside. So dive in, and know that your indoor hours are going to *really* pay off when you head outside!

Rollers are even harder than that; my husband is eyeing his again for the first time in a few years (he's a cat. rider and training for Escape from Alcatraz, needs to vary his workouts a bit) -- and I am nowhere near even touching the things. The balance and sense of rhythm needed is intense.