A week and a half ago, a pal'o'mine who works p/t at a bike shop helped me change from a 42/15 to 42/17. That's a 67" gear and
it has made all the difference!
I commute 16 - 24 miles round-trip each day. I've taken to riding up Boston's tallest hill, and then going down into the city on a road that has only a few red lights, rather than my usually flatter, more traffic-light-ridden route, so that I don't have to stop as much. I'm finding that I like climbing that hill every day, and though I can't get to the 35+ that I'd ride down on my freewheel, I do get to 26 MPH or so, spinning for short bits of time at 130 rpm.
I'm going faster than I usually try to do, as well. This bike is very comfortable at 18 - 19 MPH, at a 90 - 95 cadence, which is about a mile or two faster than I normally cruise at. Between choosing the hillclimb, and then not loafing so much on the flats, I'm def'ny getting a better aerobic workout than before. My legs are also getting a bit of a burn to them, and that's good too.
I'm still not making good track stands. My buddy tells me to go to a field someplace so that when I fall, it won't hurt as much.
But when I've had to stop, I've gotten the hang of holding the front brake, pressing down on the handlebars to cause the rear wheel to lift, and then rotating my right foot to the 1 o'clock position to be ready to stomp when the light changes.
I can see the day when I go to a 42/16. I only wish that the guy who built the bike didn't put me on a 15, 'cause it was just a wee bit too much.