Project: H/EHV

Prototype Human/ Electric Hybrid Vehicle

Most electric bikes have a range of 20 miles or less and weigh between 60lbs (27kg) and 90lbs (40kg). The Giant Lafree - the market leader - weighs 56lbs (25kg) with a range of 23 miles at an average of 14mph and is easily the most efficient, consuming only 6.7Wh per mile. This was the one to beat.

Type 42

The Highpath Type 42 weighs in at 45lbs (20kg) carrying the 250Wh 2.28kg LiFePO4 battery - giving a range of 50 miles at 15mph. With a second battery on board it weighs slightly under 50lbs, has 500Wh for a range of 100 miles at the maximum legal assisted speed of 15mph. At this speed it would be consuming around 5.0Wh per mile. Assistance for 75 miles should be available at a more realistic, though totally illegal, speed of 22mph. When the 7lbs aerodynamic front fairing is fitted the average speed should increase about 10/20%.


I had been watching the steady growth of the electric-assisted bicycle industry for some time and had noted that a heavy, cheaply made roadster style bicycle was usually the basis for the electric assist. This then would be married to a not particularly efficient motor and heavy, low capacity, lead acid battery. So it is not surprising that this combination has a short range, and is often not as fast uphill as an ordinary fit cyclist on a lightweight bike.

This idea was born when I was batting ideas around with a friend. I was wondering what would be the effect of using a fully suspended recumbent bicycle, partially faired for comfort and weather protection, married to a 14-speed Rohloff hub gear system and 3-phase AC brushless electric motor coupled to the very latest, most energy dense Lithium Iron Phosphate battery (LiFePO4). My friend was still not impressed, saying that one had to carry all that weight of the motor and battery around even when not using it. I had had an idea - I was about 14lbs overweight - so if I could lose that and build an assist system that weighed less than that - then the overall weight would be the same, but will all that power.

As this machine was going to be the most complex I'd undertaken, I didn't want to design the whole thing all at once as I knew I'd change my mind as we progressed. So the design is modular.


The front and rear of the gear box simply bolt, or slide, onto the middle and can be changed quite easily.

When I designed the gearbox the rest of the bike was nothing more than a general sketch with loads of possibilities. As the build progressed it turn into the more fully formed 'EOS Mk1'.


Frame done, and with carbonfibre seat (with fancy lattice) attached.

Missing the battery box, and handle bars. Up to this point I'd intended to fit underseat steering. However, after working with this prototype I descided on overseat steering for the Mk2. This concept become the mk1 retroactively.


The 'Mk2' with handlebars and battery fitted. The battery container is a torsion box to give lateralstiffnes amd carries a 500W LiFePO4 battery weighing 9lbs and costing £1,100!

I wasn't keen on the asthetics of the overseat handlebars, and there was a vaguness to the steering I didn't like either. This was totally re-desinged in the Type 42 which solved all these problems which, in turn, became the 'prototype'.