Beating People on the commute who have a better bike

lycra make the commute more comfortable despite looking silly to just go to work (in comparison to suit taking the tube, buses and cars).

The other reasoning is that other make their commute as their training ride to make up for the lack of time they have to do some training, so when you're racing against a lycra'd up cyclists, you're doing him a favour.

In summer I will be commuting in lycra, it's too hot otherwise and I'm not exactly going to be doing 20 miles each way in my work clothes. I sweat like a pig...