Originally Posted by yairi
I'd go with a freewheel hub if I were you, lots of them around for practically free. 7-speed (also 6-speed) freewheels also cheep and abundant.
Yes they are and for good reason. As mentioned above, 126 mm freewheel hubs are notorious for broken axles. There is just too much unsupported length. The only broken axle I've ever had to deal with was on a friend's late '80's Trek that had a 7-speed freewheel.
7-speed cassettes are fairly easy to find and 7/8-speed chains are readily available too. You can use either 7-speed freehubs or 8/9/10-speed freehubs with a 4.5 mm spacer. The only 7-speed components that are getting difficult to find are shifters. STI (RSX), barcons and downtube 7-speed shifters can require some searching.