Originally Posted by chephy

I don't think the map measures its own directions inaccurately... If it says 4.2 miles, it's 4.2 miles.

Depends on too many factors. But if there are no extreme hills etc, I'd say 15-20 minutes, depending on the rider. But don't rely on Google maps to give you the best biking route. Instead, look at the map and plot the route yourself, e.g. at www.gmap-pedometer.com. This way you get to choose the streets you like and possibly incorporate shortcuts, bike paths etc. that Google doesn't know about.