Originally Posted by
merlinextraligh
1) 1900 gram wheels are going to be heavy enough that you'll feel the difference. It will only be a fractional difference in actual time, but a bike with 1500 gram wheels feels more responsive and fun to ride than a bike with 1900 gram wheels.
I would be surprised if you kept the same hub, tires, and pressure if you could really tell the difference. I can easily imagine that a better hub makes a huge difference. And I certainly know that different tires/pressure makes a huge difference as well.
(I suppose it's only fair to point out that I have been surprised in the past...
)