From my experience some bikes benefit from heavier wheels. I rode my Griffin to work today, what a joy. I originally had sewups on it when I first built it up in 1988, and I hated it. I quickly switched to MA-40 with 622x25 back 622x22 front it is wonderful. This is my lightest bike at about 21 lbs. The chainstays are rather long for a racing bike and the front center short. I hated the handling with the GP-4 and cheap sewups. I had a simular experience in the 70's when I built up some 280 gram Mavic Gold rims on Campy HF hubs. The bike felt flimsy to me with these, I road them 5 miles then sold the wheels. Maybe I should have given myself time to get use to the feel but decided I did not need to get use to Flimsy wheels. The pro's often used sturdier wheels such as the Blue SSC's which weighed over 400 grams IIRC. I have also use tubes which are over 25 years old with many patches. I prefer the cheap thicker 100gram tubes. I once had a bike with the light latex tubes which I believe are an extreme safety hazard in a clincher wheel. The first ride I got a flat desending and the wheel deflated instantly and I struggled to stop without crashing. Butyl are much tougher and usually deflate slowly, in sewups the casing seems to hold air better so latex is not such a problem. Brian in Berkeley 70 degrees