The subway station closest to my house (Shady Grove) is about a 7.5 mile ride. But it is not a straight shot I have to zig zag through Gaithersburg and Rockville and around the doughnut kingdom of NIST. Takes me about 30 minutes. My actual route is slightly different, but google won't map it right since I make some connections that are technically off road.
Home to SG Metro
The other station I can go to, Grosvenor (everybody say Grove - Nor) is about 14.5 miles. I think I do this in 45 - 50 minutes depending on traffic lights, enthusiasm, etc. In that case I avoid (by choice) Great Seneca Highway because of the poor bicycling conditions (high car speeds and no shoulder) and Seven Locks Rd. (sharp hills and very poor road surface).
Home to Grosvenor
The thing I've discovered is that even with the time to change into work clothes after the Grosvenor ride (I can do SG in street clothes) it doesn't take any more time to do my full commute to work. This is primarilly because the route I must take to Shady Grove is so convoluted.
So the longer trip to Grosvenor has become my ride of choice since it gives me more time on the bike, which is time well spent, and no real time penalty for the overall trip. Also, the end of the Shady Grove ride takes me down 355 which is simply not conducive to cycling. The road is very busy with car traffic, and the available sidewalks (going and returning) are incredibly choppy and narrow, with the added bonus of businesses sticking advertizing signs halfway across the walkway. I could probably cut off another mile with some additional off road riding, but that would require something more rugged than the street tires I currenly sport on my commuting bike.
So I suppose this is a shout in the dark for the citys of Gaithersburg and Rockville to give some needed attention to Bicycle Access to Shady Grove Metro station, especially the mile or so approach from both north and south on Rt. 355, which is in no way bike friendly at the moment. And to NIST to give me a special cut through bike path that gets me from Quince Orchard Rd. to Muddy Branch Rd, just west of the I270 overpass.