I’ve been commuting for about 3 years now. It started by accident, my wife bought a bike and I got one to ride with her. Funny how some things work out. Her bike is rarely ridden, I’m starting a collection.. This is my winter bike, a Trek with an Xtracycle Free Radical attachment. I can haul four bags of groceries with it.
I feel fortunate to be able to do this. I know a lot of people in the business and most don’t live very close to where they work. The exercise has been great. I’ll probably be working till I’m 70 and this will help keep me in shape to do that.
It’s definitely a techs kind of bike. The light is powered by a DeWalt 12V battery pack. The rear wheel has been upgraded to a double wall mountain bike rime with a “Fat Frank” 
tire. That’s for the load carrying capacity. And a drink holder for coffee.. And a disk brake. I was amazed that I could buy a mechanical disk system for less than $50 that works like a charm.
So here’s the donor cycle, a Trek 7.2
Here it is with the rear removed.
Here I’ve added the “Free Radical”. That’s what they call the addition.
Here it is with the wheel on and working on the cables and brakes. Later on I changed the rear brakes to a disk and replaced the 700cc wheel with a 26″ mountain bike rim with a “Fat Frank” that’s over 2″ wide. That was because of the heavy loads I was trying to carry.
And here’s the bike ready to go.. I can carry 4 grocery bags in the rear plus whatever I can lash to the top board..