I have one road bike with 6 speeds freewheel. I have 7 speeds freewheel is fit between the dropouts. But the last the 14 tooth i try that is touch on the dropout. I see the axle have the wheel now is short for 7 speeds. How i repalce the axle with longer. I see difference between 6 and 7 speeds or not. Because the freewheel 6 speeds is working okay on the bike i should ride the bike like that and i not worry why i not have one more gear? And i have wheels fulcrum racing 7 with 9 speeds cassete. That wheels is fit in the old steel bike with the 6 speeds freewheel. Only i do when i put the wheel i have open the dropouts with my hands some hard for fit the wheel. The bike is ride okay like that. i want find good light weight wheels. All wheels 8-9-10 speeds freehub is have same size different brands wheels?