yeah 2.5mm's ain't much, less than an 1/8". that's like the thickness of a nickel difference. if i shimmed my cleat that would only make my leg go that much higher on the upstroke of the long arm. i have 3 different bikes, all with different arm lengths (170 fixie, 175 mtb, 165 crit road to be converted) and it doesn't **** me up when i switch bikes, but i do wonder if there will be a rocking effect especially riding no handed.