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To answer Bruce's question, please see the chart kindly provided by Specialized's ebike centre in Switzlerland. They also told me that the lights, display, controls draw about 30 W, and that the motor itself runs at about 75-80% efficiency. The lower overall efficiency that I estimated is due to...

Here is some data for Specialized Como, direct from their ebike centre in Switzerland.

Some of the ranges being reported here are very impressive. My wife gets about 80 km from her 460 Wh battery when riding a Specialized Como 4.0 mid-drive in mainly ECO mode on gently undulating terrain. As I've remarked in answer to a question in the thread "Rider's contribution to power in...

Thanks for your reply. I agree that your test would provide some very useful information; I wonder why the bike companies don't do it? To make a stab at answering your question, let's consider a flat 10K course and a rider who maintains a power output of 100 W, irrespective of the power mode...

To propel a bike at a constant speed, power needs to be developed at the rear hub to overcome the forces of friction, wind and gravity. Adding these forces, multiplying by the bike speed, and allowing for the mechanical efficiency of the drive-train forwards to the pedals, the power developed...

For those interested, there are a few numbers on the post by Pluto (Quantitative benefit of pedal assist) that demonstrate how hard an e-biker actually works.

Thanks Harry. It seems that, on the flat, the rider is often exhilirated by the power boost and actually works even harder than indicated here. For example, my wife often settles down in ECO mode to about 27 km/h on the flat, which indicates she's putting out about 170W. On the hills, though...

Attached is a short piece giving some quantitative data for the power output benefit of pedal-assist