Power, gears and frame size
Watts per kilogram decides performance on climbs, and FTP (the power you can hold for about an hour) is the basis of power training zones. A gear ratio is chainring teeth divided by cog teeth; together with cadence it sets your speed. Frame size is estimated from height and inseam and differs for road, mountain and city bikes — a test ride should have the final word.
Pace in the pool
Swimmers track pace as time per 100 m (or 100 yd). Critical swim speed (CSS), usually derived from 400 m and 200 m time trials, gives the target pace for threshold sets. SWOLF adds the time and stroke count for one length to measure efficiency — the lower, the better your technique.