You are a pretty strong and fast rider... and humble too.

Maintaining 20 mph in an urban setting with traffic and lights is really freaking hard to do and over most distances one should be happy to average 20 kmh when you factor in stops.

Fastest commute I have ever done was over my 10 mile commute from the north side to the south side at 6:30am on a Saturday where I hit every light and had some long straightaways... came in with an average speed of 23mph and was topping out at over 30 mph on some stretches.

The only "hill" I had to deal with was coming off the bridge heading south and there was virtually no traffic and it was essentially an urban time trial over a route I knew like the back of my hand and had ridden 100's of times so I knew every spot where I might have been slowed down.

I also did this when I was able to knock down a sub hour 40 on the road and was in much better shape.

Now I am pretty happy to average 20kmh on any commute...