The K-Zone: Mercury cyclemaster

If BMW's C1 represents the top end of the motorcycle technology scale, then the Cyclemaster represents the bottom end. Of course, nearly fifty years of technological development separate the two machines, so this is no great surprise. A huge number of Cyclemaster engines were produced in the 1940s and 1950s, and were supplied to a number of different manufacturers to fit in their frames. Mine is made by Mercury, an obscure British bicyle manufacturer that produced Cyclemaster machines in the early 1950s.
      The Cyclemaster engine fits into the centre of a bicycle-type wheel; the rest of the bicycle is pretty much standard, except for the cables that control the engine. The clutch and throttle controls are mounted on the handlebars. On my model, the engine itself has a 32cc capacity and is claimed to be capable of driving the machine at 25 mph (but you'd be mad to try it). It runs on a mixture of petrol and two-stroke oil, in a ratio about 20:1, and economy figures of over 90 mpg have been reported.
      The great advantage of the Cyclemaster was its simplicity. One of the design goals was that the rider could strip down and reassemble the engine in a lunch break. As the engine's inlet and exhaust ports are operated by the rotary action of the piston, there are no valves or pushrods to worry about (or adjust). In fact, there are hardly any moving parts at all. To start the Cyclemaster, you set the throttle about half-way, disengage the clutch, pedal at a brisk pace, then drop the clutch. The clutch level is mounted on the right handlebar, just above the (single) brake lever. When the clutch is engaged, the wheel motion turns over the engine, providing ignition power via an alternator. If you're lucky, the engine will fire up, and away you go.
      When it's buzzing along, you can adjust the speed using the handlebar-mounted throttle. There's only one brake - a caliper on the front wheel - and when you pull up hard on the brake lever it has the effect of disengaging the clutch as well. Ingenious. However, the bike weighs about a hundred pounds, and when it's hurtling along a single caliper doesn't do a huge amount. Moreover, by disengaging the clutch, you lose any engine braking that you might otherwise get. On a modern bike, the throttle is spring-loaded, so you naturally tend to release it when you reach for the brake. On the cyclemaster, the throttle holds its position, so you wouldn't get any engine braking anyway.
      The 1950s advertising brochures for Cyclemaster tend to show a variety of gents in jackets and ties, often smoking pipes, pootling around the countryside with big grins on their faces. For many people, a Cyclemaster was, no doubt, a cheap introduction to simple, powered transport. However, riding one today would be a different story. For a start, you'd probably have to wear a crash helmet to ride a Cyclemaster - legally it's a motorcycle. The heavy weight, coupled with the lack of engine braking and a single caliper bicycle brake, makes riding anywhere other than an empty road a terrifying experience. The only suspension is the springs underneath the rock-hard leather saddle, so with the upright riding position every bump in the road is transmitted straight to your spine. Even the cheapest, tattiest modern scooter outperforms a Cyclemaster whatever the comparison. None of this is important, of course, if you want to own a piece of motorcycling history.

Update

Kevin,
Thanks for your article re these great machines.
      I say great as I owned 2 of these and did thousand of miles on them. Most of this was in London. I then handed then on to my younger brother who also use it for a number of years.
      You are right about the "Disk" valve and I used to take great delight on friends who would tell me that there "Suzuki" had an "revolutionary rotary valve" There was a look of disbelief when I told them that MY "TOY" machine also had this revolutionary device.
      My engine was fitted into a "Normal" roadster bicycle frame. The cycle master was unusual in having a clutch, most "Mini-Motors" you used to lift the whole motor on or off the rear wheel. The alternator gave out i thing about 6 or 7 watts. If you could find and old "Pifco" lighting set this would give you very good light output. The cycle-master also had the advantage that when when you stopped at lights,lift the clutch and the engine kept on and you had lights.
      I am slightly surprised at your comments about lack of brakes. I had both cc and cc models and both had rear peddling brakes. I have heard other owners say the brakes were useless.
      Most owners did not know that the cycle master had what is called in America a"Coaster Brake" This meant that when you wanted to stop you just peddled backwards, the harder you pressed back-wards the better the braking. I can assure you that it worked! Living in London even tn those days people had no respect for cycles let alone those with a so called engine.
      The main reason this brake did not seem to work was that you had to OIL it! I never understood WHY it worked, the same as I cannot understand why some car's used to be fitted with an "Oil filled clutch" and you had to keep that topped up.
      If you look at the main spindle hub you should see a small "Oilier" if not you should see a large, flat black spring going all the way around the hub. The oiler is fixed with a little spring cap that you can lift up. It does not matter what type you have, if an oiler lift the cap and put some oil in. The spring type you just move it one one or the other (some of these even had a small "dimple" to cover the oil hole) This type was nearly always fitted to "Roadster" push bikes of that era.
      I soon learnt to know when it needed oil when you found yourself behind a big London bus and his stop lights went on and your cycle master did not slow down.
      I used to travel from Kentish Town to Kennington Oval every day to work. Of a weekend I would go out to Epping Forrest or London Airport.
      It used to cost me under one pound it "Fill her Up" including oil! One other thing I remember was that the power? output was .08 BHP at 4200 rpm! The exhaust would soon carbon up at the milage I did but you soon knew when it needed cleaning. (lack of power!) I had a spare so it did noe have to be that much of a chore.
      I hope that this has helped you.

Regards
Bob