I do it every day. It depends on elevation gain (so it could take much longer depending on the route) but usually I'm closer to 15 minutes than 20. 15mph on average for a daily bike commuter doesn't seem unreasonable at all to me.

It depends on location, if you're biking in a city at rush hour you're stopping every other block, getting stuck behind other cyclists, and at least where I live, constantly slowing down to avoid getting killed by potholes. There's basically no way you're doing 5 miles in 20 minutes.

On the other hand, if you are in heavy traffic stopping constantly at lights other traffic is also going to be travelling at that same slow speed.

That's fair. I biked in San Diego last week and the lights/potholes were brutal.

You're claiming you can ride 5 miles in closer to 15 minutes than 20, and through a city?

If you commute you will mostly ride on dedicated bike lanes without many stops so you can go at full speed most of the way. I've commuted around 3 miles in a not so bike friendly city in Europe and it took about 15 minutes since there are dedicated bikeways without any traffic lights you can take most of the way.

If you commute in rush hour that is actually a lot faster than going by car, so biking is the fastest option available.

Edit: And that was at a leisurely pace, similar to the effort of walking.

Google maps pads their bike times by a huge amount. (I just googled 8km in 35 minutes and got results asking about that as a running pace).

That's due to the sES spamfest fitness blog driven results.

Google maps calculations are decided by Google and take into account padding plus some degree of inclination calculation

I used to do a 5 mile commute. I didn’t have to deal with any major elevation changes, and it was about 35 minutes. Maybe a professional athlete could do it in 20, but they would still have to wait at stoplights occasionally. You will definitely arrive sweaty unless you are in a very cold climate. All that said, I consider 5 miles to be pretty reasonable for a bike commute.

You are both right: 5 miles is about 20min on an electric bike, but 35min on a traditional bike.

I do a 4.8-mile trip on a class 3 ebike (28 mph) consistently in 14 minutes in San Diego north county.

That would be an extremely leisurely pace. If you commute regularly on a bike and are reasonably fit, you should be able to ride at about 12 mph without breaking a sweat, which gets you a time of about 25 minutes.

Obtaining a speed of 12mph is not difficult for most reasonably fit people.

_Averaging_ a 12mph pace with signal lights, traffic, and stop signs is an entirely different story, especially in a busy cities.

Sure, if you never have to wait for a stoplight.

Seems possible indeed: https://www.youtube.com/watch?v=Atkp8mklOh0

YMMV. Google map estimates for cycling are very inaccurate in my experience.