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HUMO™ | the HU(man) MO(tor)

the first ever human powered car
for people, for the planet


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Frequently Asked Questions

Do you want to know some more about the science behind the HUMO™? Then see if we have covered it by looking at our Frequently Asked Questions below.

If there is a question you would like to ask, that isn't covered below, then please feel free to email us. We can then get our thinking caps on.

A. How it works - some very simple physics

torque = power x perpendicular distance

Torque is the strength of twisting, and it is that strength that is used to drive the HUMO™ forward.

Power is what the driver's body can provide. Sadly, without resorting to illegal steriods, it is difficult to obtain any revolutionary increase in body strength.

Perpendicular Distance is the length of the crank-lever between the axle and the pedals. On a bike, the cranks are normally limited to about 15cm - 17cm (6" - 6.5"). Any longer and they will hit the ground! This introduces a fundamental and unavoidable restriction of the torque available.

On a HUMO™, the cranks rock through the vertical position. With a choice of axle positions you can end up with cranks that are up to three times the length of a normal bike crank.




A. However you like!

OK, not perhaps the most constructive answer, but the HUMO™ can be used to replace any short car journey - either a quick pop to the shops or as a daily commute to work.

Given its efficiencies over conventional bikes, there is significant scope for the HUMO™ to be used recreationally.
HUMO™ Beach buggy anyone?

But most importantly, as a low-cost, low-impact form of transport, there are countless ways in which the HUMO™ could be used in your home community. Here are some of our ideas -

        an ambulance? With two drivers increasing the power?

        a water-carrying van? Low-geared for weight-moving?

        safer school transport?


Discuss it with your friends, and with us via the HUMO™ Community.

A. We are working to encourage HUMO™ makers to set up manufacture in their home area. It will be helpful for them to know of potential customers, so one of the purposes of the HUMO™ Community will be to facilitate communication between customers and makers.

A. This will depend on what you specify. Our guess at this moment is: more than a cheap bike, much less than a car.

A. This will depend on its speed, and how the authorities rate it. Part of the HUMO™ Community's remit will be to collect evidence and liaise with authorities to establish useful rules.

Well firstly, we had better explain what a sprag clutch, and ratchet are. I say 'we', but other people can do that far better than we can, so check out their definitions below -

Wikipedia - Sprag Clutch
Sheldon Brown - Ratchet

Sprag clutches are an 'industrial' solution, and needed for high levels of torque - which result from the need to move a heavy weight.

Ratchets are normal in bicycle-technology, and suitable for lighter weights - which is what I advise most HUMO™ builders to aim for.

Both the HUMO™ prototypes which you can see in the video used sprag clutches. I had hoped to use ratchets for the second prototype, but they couldn't take the torque because the vehicle weighed 115kg! When the 240mm crank was pushed hard, the ratchet collapsed. So we fitted a sprag clutch - check out the photos!

For a light vehicle powered through a single drive-shaft by one person I would certainly use a ratchet. As the power increases - say 4 people powering through a single shaft - a sprag clutch may well be better. Please let us know what you discover in practice.



A. Yes . . . definitely.

Although our first prototype is looking to test the speed and power of a light and efficient HUMO™, future prototypes will assess the improvements made by adding lightweight electric motors. Watch this space!!

When making and testing our prototypes, we found it advantageous to make the front wheels smaller than the rear wheels for 2 reasons -

        the steering is easier and more accurate.

        The weight of the driver is better distributed onto the rear wheels - which have the drive - for more power, especially uphill.


The Sinclair C5 was launched in Jan 1985 as a three wheel one person electric vehicle. It had a reported top speed of 15mph and a range of 20 miles. It was equipped with a 250 watt electric motor which regularly overheating climbing hills, reducing both its speed and range significantly.

Sebastian writes -
In about 1986 I was driving to work in a company Volvo. I was on a road where I normally did about 30 mph. Suddenly, in front of me there was what looked like a mechanised insect. I recognised it as a Sinclair C5. It seemed like a very irritating, puny obstruction. I pressed hard on the accelerator, and shot past at about 45 mph, having guzzled some petrol and sent lots more lead and CO2 into the atmosphere . .

Wikipedia has plenty of info re the Sinclair C5.

The main differences between the Sinclair C5 and a good HUMO™ are:

Sinclair C5
Cruising Speed
8-10 mph
25+ mph
20 miles
Weather Protection
Designed for environment
Driver Visibility
Being seen
Very low
Much higher
3 wheels
4 wheels

Sinclair C5

Sinclair C5

A. It's much safer than most recumbent bikes, in which the drivers lie back to get maximum aerodynamic benefit. Other road users find this sort of recumbent bike difficult to see, and visibility is also poor from their driving seats. When recumbent bikes have a more vertical seat, they still have the drawback of using traditional rotating pedals, which only give a power-stroke for about 60% of the time.

A. 'Normal' human-powered vehicles are generally like recumbent bikes, but with stream-lined light-weight shells. They have achieved over 80 mph, but are not practical road vehicles - for example, they have to be held vertical by team-mates when stationary! The very high speeds have been recorded in ultra-thin air on Battle Mountain, Nevada. It will be fascinating to see how an ultra-streamlined HUMO™ will perform against them.

A. As the vehicle must be light, it must be easy to store it in safety. Many people store their bicycles in their homes and offices. One contributor to the Talk London blog reported that he has had 18 bicycles stolen since he moved to London in 1980 despite using the best locks available. He says he now uses Boris Bikes, despite their lacklustre performance, because it is so painful and irritating when his own are nicked.

With small wheels, this design of HUMO™ can be folded, and carried or pushed through a normal door. (This idea would be patentable, but I decided to include it in the website, which means that it is in the public domain)


Any questions? Please get in touch -


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Original music © Benedict Cruft