Sunday, 29 January 2012

Specifications for the Sinclair C5 Electric Vehicle

The Sinclair C5
Picture from the Sinclair Research website

Read my C5 review here.

  • Overall length: 1.744m (5' 9")
  • Overall width: 0.744m (2' 5")
  • Overall height: 0.795m (2' 7")
  • Wheelbase: 1.304m (4' 3")
  • Rear track: 0.630m (2' 1")
  • Empty weight (without battery): 30kg (66lbs)
  • Battery weight (each - one or two could be fitted): 15kg (33lbs)
  • Maximum recommended gross weight (including rider): 150kg (330lbs)
  • Chainwheel: 42 tooth
  • Rear chain sprocket: 20 tooth
  • Cranks: 130mm
  • Chain: 1/8", 181 links
  • 250W motor driving a 13:1 gearbox
  • Max motor revs: 4100 rpm, giving 315 rpm at the rear wheels
  • Battery rating: 36 Ah, @ 5 hour rate
  • Battery rating (in operation): 15 to 28 Ah, depending on motor load
  • Front wheel size: 12 1/2 inch (203mm), with a 2 1/4 inch tyre fitted NB: caution - please read notes and comments below
  • Rear wheel size: 305mm, with a 2 inch tyre fitted NB: caution - please read notes and comments below
Carrying capacity
  • Rear boot(trunk): 28 litres (1 cu. ft.)
  • Maximum recommend cargo weight: 10kg (22lbs)
  • Maximum speed:
    motor only: 15 mph (24 km/h)
    pedal gearing is too low to allow pedal assistance to get much above the speed quoted above
    maximum speed (motor only) can fall to 12.5 mph (20 km/h) in cold weather
  • Acceleration (motor only - "average" weight driver):
    0 - 5 mph (8 km/h): 1.8s
    0 - 10 mph (16 km/h): 6.9s
  • Range:
    1 battery, motor only: c. 13 miles (c. 21 km)
    2 batteries, used sequentially (that is to say, using one battery only first, then using just the second battery), motor only: c. 25 miles (c. 40 km)
    2 batteries, wired in parallel, motor only: c. 33 miles (c. 52 km)
    range can be doubled in all three cases by using the pedals to move away from stationary, and by using the "burn and coast" technique
    range could fall by up to 50% from the above values in cold weather.
  • Information is taken from several sources:
  1. the "Sinclair C5 Owners Handbook" by Sinclair Vehicles, 1985, the handbook supplied with all new C5s, particularly page 32
  2. the Sinclair C5 original marketing brochure "Sinclair C5. A new power in personal transport."
  3. information about performance and battery characteristics is primarily drawn from the work of P. Milner and P. Newman, who both worked for various Sinclair companies, and were both heavily involved in the development of the C5. Their data has been published in "The Unofficial C5 Service Manual", to which they both contributed, and elsewhere.
  4. additional information about cold weather performance is drawn from an Automobile Association report from 1985, quoted in "Sinclair and the Sunrise Technology" by Ian Adamson and Richard Kennedy, Penguin Books, London, 1986.
  • The wheel sizes can be confusing as they are listed by Sinclair as different sizes in different places!
    NB: caution - please read comments below
  1. The front wheel is listed in the Owners Handbook as being 12 1/2 inch diameter, while the rear wheels are listed as being 16 inch diameter, while they are listed in the brochure as being 317mm and 12 1/2 inch diameter for the front, with 406mm and 16 inch diameter being quoted for the rear pair, despite their actual diameters being 203mm and 305mm !!!
  2. The "normal" "modern" bicycle convention is to list a 317mm diameter wheel as a 16 x 1 3/4 inch wheel (a size apparently popular on older Schwinn children's bikes), while a 406mm diameter wheel is a "decimal" 20 inch wheel size, and is the same as the wheel size on my folding bike! Such 20 inch wheels are fitted to BMX bikes, children's bikes, folding bikes, trailers and some recumbent cycles
  3. The brochure (presumably prepared by an external advertising agency) seems to have assumed that Sinclair followed a different sizing convention for stating wheel size than was the case. Sinclair list the wheel sizes as 12 1/2 inch and 16 inch, but the brochure has assumed that they would be more generally known as 16 inch and 20 inch wheels in the bicycle world - indeed a 16 inch (actual) diameter wheel with a two inch tyre on it would be 2+16+2 = 20 inches in total diameter! AND 16 inches in metric is 406.4mm, so the brochures conclusion is not irrational.
    However, the TRUE rear wheel size is a 12 inch (actual diameter) wheel with two inches of tyre at the top and bottom, giving 2+12+2 = 16 inches!
  4. Buy tyre sizes by the ISO size, not the "inch" size" - tyre sizes (according to the brochure) are 203mm x 57mm (front), and 305mm x 51mm (rear) NB: caution - please read comments section below
  5. The late, great, bicycle mechanic Sheldon Brown has a feature article on wheel sizes on his website - worth a look to give you an idea about how different measurement systems can be confusing (and confused!), and reminds us all why the "modern" ISO (previously known as ETRTO) measurement system is so popular!
  6. The conflict between the C5 having 2 inch tyres on 16 inch (actual diameter - i.e. 406mm) wheels, as suggested by the brochure, or having 2 inch tires on 12 inch (actual diameter - i.e. 305mm) wheels can be resolved by dicussion with an owner, visiting a C5 in a museum (I believe there is one in Manchester), or careful comparitive measurement of available photos.
The Sinclair C5 brochure
C5 Alive user group user site

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  1. Hi Pedal Pusher,

    just like to say thanks for taking the time to post these specs.

    I would also like to add some corrections to your page.

    Maximum speed:
    15 mph is 24 kmh and not 15 kmh.

    2 batteries, used sequentially (series) OMG, motor only: 0 miles (0 km).
    If the batteries are connected in series on a standard C5 both the Control Unit and POD (indicator unit) will be blown.

    " but they would be more generally known as 16 inch and 20 inch wheels in the bicycle world!".

    Sorry, but being a C5 owner I must contradict this statement.

    The overall diameter of the front and rear wheels are as per 'established bicycle convention of listing the wheel size including that of a tyre attached'.

    Original Sinclair tyres with the following text, as part of the side walls, are front 'SINCLAIR 12½ x 2½, 62 x 203 Made in Thailand', and rear 'SINCLAIR 16 x 2, 54 x 305 Made in Thailand'.
    Why the brochure quotes '317mm x 57mm (front), and 406mm x 51mm (rear)' is a complete and utter mystery.

    I now use Schwalbe City Jets, front 54-203 (12 x 1.95), and rear 54-305 (16 x 1.95).

    1. Thanks for that - my data is better than my typing (of course 15mph isn't 15kph!!
      As for the tyre sizes, bicycle wheels changed the way they were measured, so, for example a 20" wheel can be 406mm, 419mm or 451mm.
      The usual tyre (tire) size guide used is that compiled by the late, great, Sheldon Brown :
      It being twenty-odd years since I actually drove (rode) a C5, and that was just the one occasion, and although I saw several in the local electricity shop at the time they were made, that was all a long time ago :-)
      It would appear that I am not the only one to be confused by tyre size :-)
      Certainly I don't remember the tyres being as big as the 406 tyres on the bike I ride now.
      But, as you have one, you should know what size they are better than me from distant vague memory and a manual (!)

      On batteries, I have written "used sequentially", meaning "used one after the other", not "wired sequentially" as in wired one after the other i.e. in series. Perhaps you might assist me in choosing a better form of words, as I was not aware that there were two apparently valid (yet very different) interpretations of what I wrote, yet I do see your point, particularly with folks using English as a second language.

      Having said all that, how did you find my review (linked)?