Though, I agree w/all this and previous advice on flat vs drop bars, DIY vs lbs purchase, etc., I'm offering my perspective re triple cranksets and commuting. As you progress you'll find yourself using one chainring in the front for the larger percentage of your 20km commute. Unless you've several 10-20% grade hills on your route a triple will be overkill. Or if you want to use your bike for touring of any sort, ie weekenders, overnighters, day-tips, off roading, etc. Then by all means a triple. With the gearing mentioned above. Just don't practice on the walls inside your residence.

However, I'm going to recommend a double or even a single chainring set-up for most of one's commuting needs. Here's a couple of bikes to give you an idea of double vs triple: http://www.bikesdirect.com/products/...ntom_cross.htm or http://www.bikesdirect.com/products/surly/longhaul.htm Note they both have the same cantilever brake set-up...entry level. Both are set up for rack/bags and have drop handlebars. One has bar-end shifting. Ok for touring, not so ok for commuting. STIs(brake/shifter combo) are better in traffic. One's a triple, one's a double. One's steelframe and one's aluminum. Aluminum's fine for 20km commute's, not for 200 mi weekenders. One's 1000.00US, one's 800US. One's got a great rep and the other's a fine bike w/comparable componentry, but IS aluminum.

And if that's not enough to explode your head, here's one more for you: http://www.bikesdirect.com/products/.../cafe_noir.htm A flat-bar road bike w/braze-ons for a rack/bags. Lower spoke count means less load capacity, but should be fine for commutes and weekenders. Cro-Mo frame(steel) w/a carbon tapered fork give a more comfortable ride while subtracting weight, overall. 700.00US

The suggestion here isn't that you purchase any of these bikes it's to give you an idea of what's out there and how you may apply the different configuations to your particular needs. If you go w/a cross bike make sure the tires are exchanged for road tires as the stock tires are usually too soft for street use of any duration and will wear down quickly thereby raising your likelyhood of flatting.

BTW, I have this bike: http://www.bikesdirect.com/products/..._cross_cx3.htm Only it's the 2008 version w/2009 upgrades. It has a 'compact double' w/50tx36t crankset and a 9 sp 26tx12t cassette. Mine's got over 7000 commuter miles w/only minor adjustments to the brakes(as the pads wear), der cables, frt and rr der 'limiting screws', chain maintenance(cleaning,lubing), a couple of rear wheel truings and rim, cassette frame cleaning once per week or after rains. Also, I swapped the stock tires to Schwalbe Marathon Plus 700x28mm. The bike's been a hoss and I couldn't be happier. I'm 5'11" and got the 56cm version. Delta mega rack w/Jandd saddlebags...not recommended as they're small and NOT waterproof at all. Mine are as I brushed 'em w/3 coats of Thompson's Water Sealer inside and out.

Whatever you decide on just get out, ride and have fun.