I've been fixing up a couple of mid-1990's 26" steel mountain bikes, to use use as commuter/utility bikes. It's been a lot of fun to fix them up. I'm not brave enough to mess with wheel truing and bottom bracket issues yet, but I have recabled one bike and learned how to properly adjust derailers and brakes. I have to admit that I have no idea what gearing makes for a good road-use mountain bike. Does anybody have any good advice on which bike has the more appropriate gearing for a largely flat 15-mile one-way commute, with a couple of short but wicked hills?

The first bike is a Diamondback Topanga. $40.00 off Craigslist.
Chainrings: 22/32/42
Cassette: 7-speed, 11 - 28 teeth


The second bike is a Schwinn Frontier. $25.00 at a garage sale. This bike has come a long way since the picture was taken.
Chainrings: 28/38/48
Cassette: 6-speed, 14 - 28 teeth


Also, is it common to choose a larger framed mountain bike for road use? The Topanga is the size that I'd naturally choose for offroad use. I'd guestimate it to be about an 18" frame. The Schwinn seems to be a bit more comfortable to ride onroad, and is advertised as a 23" bike, but feels more like what I'd expect from a 19 1/2 or 20" frame.