I think the top speed on descents is relevant..its fun to know what other people are hitting.its quite a rush to even go that fast on a bike at all.

Myself I average 15.5 mph on my commute, but I have cracked 30 on a flat stretch for a block or so..prolly had a tailwind.normally I don't see my mph above about 23-24 on my mostly flat commute.

The fastest I've been on my bike was fully loaded touring setup going down the backside of morgan territory rd (into dublin/livermore) where I hit 58.8 mph .