Boulder All Road, Surly Long Haul Trucker, Bike Friday New World Tourist, Breezer Uptown 8, Bike Friday Express Tikit, Trek MultiTrack 730 (Problem? No, I don't have a problem)
Most of Rattlesnake Gutter Road is closed to motor vehicles. It is more of a walking path than a road. The one time I rode up it from Montague Road (on a Surly LHT with 35 mm tires), I got about halfway up and then walked my bike the rest of the way. At its steepest, it's about 16%. Now, it was 2008 when I last rode Rattlesnake Gutter. I just did D2R2 yesterday, and while it was only the 100K, I am a stronger climber now than I was then. I should give it another try. But I wouldn't want to do it with gear for an S24O, unless you're a strong rider who likes hills.
Coming from the north, things would be better, but I'd worry about losing control on the steeper bits, and I'd make sure my brakes were really, really strong.
HillRiderEast's photo is of the very beginning of the road, before it becomes a steep dirt path.... :-)
Depending on where you're going, Cave Hill Road is a decent alternative. It's paved and only moderately steep. North Leverett Road, starting at Route 63, would be my suggestion if you don't like hills; from the west, it climbs steadily but it's rarely more than 4%, and I think the steepest grade is only 8%. If you'd like more detailed suggestions, PM me.
P1010046.jpgIt was great last week when I rode it. Mostly smooth , few bumpy areas. There is a jersey barrier to prevent cars from going on it. I would highly recommend the rubel bike maps. They cover the whole state of MA for bike roads with hills shown. I was on 26" touring bike with 1.75" tires. Jennison road is nice too. This shot is going toward Sunderland. The other side is somewhat loose and steep, it was OK going down but would be harder to pedal up.