Originally Posted by
Moe Zhoost
Exactly. A heavier load means leisurely acceleration and slow going up hills. However maintaining speed on the flats is no problem and you actually gain additional momentum going down hill.
And nobody can dispute that shaving a few pounds from the engine is easier than from the bike.
I think you will find that there are plenty of people would find it easier, cheaper, and more permanent to cut a few pounds off the bike than themselves. Plus the engine on a bike (you) is "sprung" weight while everything on the bike itself, including the things in your panniers are "unsprung". That's not true if your bike has a suspension system of some type. The right kind of suspension can actually improve performance. Anyway adding unsprung weight decreases performance more than adding sprung weight.
Does it matter that much for most people's commute times? Probably not but it might matter a lot in how the bike feels. A lighter bike is also more convenient if you ever need to lift or carry it for any reason.