Whether you notice the weight difference will depend on the type of riding you do and the weight of the heavier bike. If you're doing a lot of hills and trying to scale up them as quickly as you can you will notice the difference on the climbs. If you're riding in groups and lose a wheel and need to accelerate to get back on you will notice the difference. If you're doing long rides with lots of hills you will notice the difference-- even more later in a ride. Four pounds is a heck of a lot of weight to me..........especially when you start thinking about the difference between a 16 lb bike and a 20 lb bike........