Originally Posted by
billyymc
Go look at bike times/speeds from sprint distance triathlons. Granted, there's a swim first and a run after, the level of athlete varies significantly, and the courses may range from hilly to perfectly flat, but there are usually a small % of riders over 20mph for their ride. That's a non-stop traffic controlled ride where the rider is probably riding pretty hard, for ~ 12 or 14 miles depending on the race.
Things like triathlons and distance runs are interesting competitions because the elites are out there with the novices. So while it may seem like only a small % of riders are averaging over 20 mph, the elites as a group will be well into the mid 20s or higher.
Though a more ideal situation than a commute, a triathlon isn't perfect for top average speeds either. For me at least, I get up to speed at a moderate rate after getting out of the water and by the same token, I'm dialing it down a bit on the home stretch of the ride to get ready for running. I'm sure there are Olympic distance triathletes who do the occasional sprint and they probably can go full throttle for most of it.