Originally Posted by
cmolway
Everyone's commuting goal is different. For me, a big part of riding into work is the idea that it counts as 30 minutes in the gym. It helps that I have a locker room at work where I can shower and change.
Talking of the gym, isn't there a thing that sensible people do before trying to ride fast called a warm-up? Try to ride fast as possible without doing one and you risk ending up with a injury - maybe not on Day 1, but it isn't just Day 1 that counts.
Reaching a 20mph average on a 10 mile (?) ride gets even harder if you allow for 5 minutes at 15mph to warm up, but you should. Riding at 20mph will take twice the energy of riding at 15mph; it's a bigger physiological difference than it sounds. A commuting 20mph, which might be made up of repeated sprints up to 25mph, needs a warm up even more. I'd really advise the OP not to push harder than he is already doing for those first 5 minutes.