Originally Posted by JohnDThompson

Bicycle weight does matter, but perhaps not as much as you'd think, unless you're in peak physical condition and racing. With bicycles, the weight of the bike is only a fraction of the weight of the rider, while with automobiles, the opposite is true. It's often more cost effective to reduce body mass rather than bicycle mass, and depending on your BMI, it can be healthier as well.

Originally Posted by Doohickie

The weight of a bicycle matters, but not nearly as much as it does on a cargo van.

I checked and running with no cargo versus running with full cargo for the Mercedes Sprinter (as an example) results in a 70% increase in weight. A 200 lb. bicycle rider riding a 30 lb. bike versus a 20 lb. bike is an increase of 4.5%. So yeah, it matters, but not enough to affect performance nearly as much as loading a cargo van.