I am pretty hypervigilant about fit but others, not so much. Two riding buddies flew into town last weekend for a charity ride. Both rented Specialized Allez bikes and each ride a carbon bike in their home town. Takeaway? They rented generically to body size...one a 56 and other a 54 and both thought their fit was better on the rented bikes than their bikes at home. Pretty comical really. Rent a bike, do a 80 mile ride and I feel better after the ride on a AL bike without a lot of fit adjustment.