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2014 Pioneer Run, part 2

October 13, 2014

We’ll start part 2 with my favorite of the old crocks, Harry Karslake’s famous Dreadnought.  The bike is even better known than the man, but that is only due to its longevity compared to his.  Mr. Karslake was a representative of an oil company (Wakefield I think) and his nickname was “Oily”. As part of his job duties he rode quite a bit in the pioneering days before WWI, and eventually was employed by George Brough as his right hand man at Brough Superior. The early magazines are filled with his exploits, including competing in a number of events like time trials, reliability trials and efficiency runs where he was often able to get either the fastest time, the most accurate time or the most miles per gallon of fuel. He also wrote a bit and gave lectures to teach riders of the veteran era how to get the most of themselves and their machines.  Do a search here for “karslake” to see 34 typical mentions of his name in a 6 month period of 1911 of The Motorcycle magazine. Eventually he was the founder and librarian for the Association of Pioneer Motorcyclists, which you can join if you’ve had a motorcycle license for the past 50 years…P1010242

Upon his death, Oily donated the machine to the VMCC, the world’s largest club for old motorcycles. It is ridden most years on the Pioneer Run by the club president, and has been the very first bike to depart every year since the first run in 1930!  It is often the first bike to finish too, with enough performance to keep the later machines from ever catching it.  Click here to read more about the build of the bike.P1010243


An American in England. This 1912 Excelsior single wasn’t quite unique, and was joined by a 1913 twin.



The Wilkinson four. Quite a machine.



This big twin Ariel looked great in green with red and grey. The gearbox was offered in this layout for 1914 only I think, and the later models can be identified by the kicker being on the other side. It is a minor difference, but the Sunbeam club is diligent about keeping track of which bikes are pre1915 and therefore eligible for the Pioneer Run.

 on pioneer run

The ‘13 Veloce took me all the way to the Brighton beach without any issues. If you get bored and want to read about how it was restored, click on the green link in the previous sentence.


Sunbeams have always been regarded as gentleman’s motorcycles. The very fine black jappaning finish and the enclosed chain drive were two details that added to its reputation. Sunbeams began with chain drive from the start of their production, even while others were still using belt drives. (only one ‘Beam model used belt drive, by requirements of the French army during the Great War). The company is a very old one, with origins in 1790 and they were famous for their black finishing work decades before they began making bicycles and motorbicycles.



This series of photos shows some varieties of the Zenith Gradua. As a mechanical design engineer, I’m always excited by designs like this or the Rudge Multi. Builders and buyers of motorbikes knew that gears were needed from the pioneer days c1903. Some were offered with and without clutches, to echo the features of the autocars of the era. However they weren’t seen as being required 100%, and they only increased the cost of the machine, sometimes more than they increased the value of the machine.  So it was some years before they became standard fitment. Even after the proliferation of countershaft gearboxes in the 1914-1915 era, bikes were still offered with primitive clutchless belt drives after WWI, especially on lightweight models and ladies’ models. In between days, bikes had a variation of specifications. The early NSU two-speed gear on the crankshaft was a common fitment, and other proprietary gears and/or clutches were offered by Mabon, etc. But the Zenith design excelled with its complex belt and pulley arrangement.  A crank lever worked a linkage that changed the width between the halves of the V belt pulley on the motor.  By driving the two halves closer, the belt had to ride up the V to a larger diameter, which made the bike go faster. But that larger front pulley also made the belt tighter on the rear pulley, so something was required. Rudge’s design was to have linkage to change the rear pulley size in conjunction with the front pulley.  Zenith went the more complicated way, and moved the rear wheel forwards or backwards to keep the belt tension constant. That is, the wheelbase was altered via that same linkage to the front pulley. This was done by a series of gears which pushed plungers in the frame chainstays, moving the axle. The gear sets were tied together with a chain that ran across the frame, lest the axle get cockeyed.P1010257

In principal it is fairly straightforward, but there are some complications. The first is that the brake needs to move with the rear wheel, but the brake pedal does not! A compensating linkage accounts for that, while the brake shoe is mounted to the moving portion of the left chainstay.P1010232

The other complication is the sheer number of moving parts required. Three gear sets, two sprockets and a chain, plus the linkages and associated bearings, not to mention the cam and bearing hardware in the motor pulley itself, all added to the cost. And as the exposed components wear, the modern rider must replace or repair items to minimize the slop in the system and keep it moving smoothly. P1010236

Like the Rudge Multi layout, the Zenith Gradua was eventually done in by its limited variation in gearing.  They simply couldn’t be driven to a very low gear and also to a very high gear in the way that a three speed countershaft gearbox could. But for a few years they were the best thing that a rider could imagine, and many races were won by Zenith Graduas against single speed bikes or bikes with fragile gearboxes. Zenith was famously barred from competing in some events as they had an unfair advantage. Zenith jumped on this and added the word “BARRED” to all their advertisements.P1010237

Three or four Zenith Graduas were on the 2013 Pioneer Run. A nice assortment of single and twins in different colors and some with left hand or right hand control levers are shown in the photos above.


This neat Bradbury has the above-mentioned NSU two speed on the motor crankshaft.  The lever above the fuel tank can be spun around to choose high or low gear, or a neutral can be found in the middle if the rider is careful. The drive is taken up by a series of metal discs which make a particular squeal when the hand crank is spun.


And just to be different, here is a 1909 shaft drive FN.

6 Comments leave one →
  1. Jim Abbott, Tucson, AZ permalink
    October 13, 2014 3:53 pm

    Pete: Re. the 1912 Excelsior Single, I think any motorbike built before 1915 that still runs is unique.
    Jim A.,

  2. Antony Gullick permalink
    October 14, 2014 2:49 pm

    Hi Pete
    Interesting stuff. I have both a 1911 zenith Gradua single which is my regular veteran ride and I also have a 1902 clement.
    The excelsior is going together and really looks something. Thanks for another great post.

  3. Geert permalink
    October 15, 2014 12:26 pm

    The control levers for the Zenith Gradua system is on the right for single cilinders ,on the left for the twins.
    Probably because the twins had the exhaust on the right.


  4. Nick Smith permalink
    April 10, 2015 5:52 am

    Hadn’t spotted that the operating levers were on different sides depending on what motor you had in your Zenith…

    Not sure about the mention of plungers to move the wheel – the patent (26163/08) shows Acme threads in the chainstays, each of which is operated by the small sprockets by the bottom bracket.

    I suppose this would give a ‘positive’ movement of the wheel in both directions, and enable it to be synchronised with the opening and closing of the pulley through the bevel gear on the end of the handle.

    A contemporary offering, the Osborne, had the mechanisms working independently: they had offered a four-position variable engine pulley from about 1904, and ended up offering a machine with a hand-operated pulley (coffee-grinder handle), and foot operated movement of the rear wheel. Patent 23801/08 has more…

    • April 10, 2015 8:34 am

      Agreed Nick, I could have been more clear in the description. The plunger parts would be the acme nuts (attached to the rear axle) that translate front to rear when the two acme shafts spin in the chainstays.

      Thanks for the top on the Osborne. I hadn’t seen that before! Certainly an interesting precursor to the Gradua/Multi/etc.

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