I understand that the 7000 has a lighter aluminum frame. Does that really make a noticeable difference. I weigh 210, So is a lighter frame really that big of a difference??? Which one is more durable for riding on pavement and Bike paths? I guess it would be the 820 because of the wider rims + heavier weight, but I am not sure...At the shop near my house the 820 is on sale for $280 and the 7000 costs $360, but price is not that big a issue. Thanks!!!