Custom Build Gallery, the Laprise Boardtracker

This tribute reproduction of a vintage board-track racer really impressed me, and it is one of the most exciting ebikes I’ve had the pleasure of writing about. The builder is Simon Laprise, and he is from Montreal, Quebec…in Eastern Canada.

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The 1913-15 Cyclone boardtracker

Simon’s inspiration was the boardtracker motorcycles from over 100 years ago, and specifically the Cyclone brand from 1913-15. There were several features that made the Cyclone an advanced competitor, but they suffered from a fatal flaw that was not addressed early enough to allow them to survive against their competitors from Indian and also Harley-Davidson….

A fully-restored 1914 Cyclone boardtrack racer.

The upstart Cyclone company adapted several features in their engines that were very advanced, and were copied from the fledgeling aircraft industry. Although cylinder head designs with 4-valves each had already existed, they were quite expensive. Racing designs were generally produced only in order to sell commercial motorcycles for a profit, and customers only wanted to buy the model that had raced. It was often less expensive [at the time] to get more power by increasing the displacement, or to add more cylinders…rather than increase the RPM’s, which was the main benefit of the increased breathing ability that the four-valve head designs provided.

Once the decision was made to use the more affordable 2-valve design, the Cyclone engineers took the risky decision to incorporate an overhead cam instead of a more common single-cam overhead valve (OHV) design, which would have used four push-rods to actuate rockers. Doing that reduced the reciprocating mass, allowing for more RPM’s. This was partially accomplished by using a spinning shaft and a 90-degree bevel gear, instead of reciprocating pushrods.

One method they used to help the engines’ breathing [within the restrictions that they had imposed on themselves] was that…they canted the valve angles to allow for larger valves. Because of that, they also had to “dome” the piston crowns [instead of using flat-topped pistons] to keep the compression ratio at the best possible level. A compression ratio of 5.5:1 is low by modern standards, but it was in keeping with the poor quality of the low-octane gasoline available in 1913…

Simon’s Cyclone runs almost silently, compared to the original Cyclone which didn’t even have any mufflers.

Since the several good design choices that the engineers had made would allow the Cyclone engines to run at higher RPM’s, they then made the choice of incorporating the more expensive “caged ball bearings” on the crankshaft. The engines of that era normally used a “splash” irrigation to oil-lubricate the bearings, but…if you did not include a now-modern pump-pressurized system, that decision was as good as the bearings could be, compared to the bronze bushings that were common for their competitors.

Modern engines actually do use bushings for their crankshafts (called “plain bearings”), but…they are only adequate for the modern level of performance if you also couple it with a pressurized oil-pump system.

The fatal flaw of the advanced Cyclone engines was how they realized just a little too late, that…the exhaust valves needed more cooling than they had provided. Here is a pic of the fins around the intake and exhaust valves of a flathead 1910 Flying Merkel. There were several later-design options that might have helped the Cyclone to reduce exhaust valve failure. The addition of cooling fins on the exhaust was a solution that was known and available at the time, and the decision to delete this feature was their fatal flaw…

As far as the survival of the commercial version of the orphaned Cyclone brand of motorcycle, you may have noticed that the brakes…uh…(*cough, cough) well, I guess just the single brake…(*nervously looks back, a little more closely at the pic above)…um…apparently…they never produced a motorcycle with ANY brakes. I’m sure that “at the time” there was a market for an advanced high-performance motorcycle with no brakes at all, so…maybe it’s just that their advertising was inadequate?

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The Frame

The motorcycles from this era used an “easy to manufacture” round sideplate in the crankcase of the engine, and this makes it easy to produce a visually similar electric version today. A frame that has this round lower section is often called a “loop” frame.

The Loop-style frame

The forks of the 1914 Cyclone were a simple added-truss style that was common on the bicycles of the day. However, Simon decided to copy the stronger fork design used by the 1910 “Flying Merkel”

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The Motor

Simon custom-fabricated a motor-mount to hold the geared hub-motor in the place where the stock round crankcase is normally located.

The custom motor mount

One of the features that really grabbed my attention was how Simon located the rear disc brake onto the left side of the motor, instead of on the rear wheel.

The rear disc brake.

The old-style “one piece” cranks [that are often found on beach cruisers] require a large diameter bottom bracket shell. The are adapters that will allow a modern smaller-bearing 3-piece crank cartridge to be inserted, but…most of those locate the new cartridge in the center of the BB-shell. Simon used an “eccentric” BB adapter, and that style can be used to tension a chain in a “fixie” style of bike, by rotating the adapter to move the BB-spindle from the rear towards the front.

The aluminum side-plates that hold the motor in place.

I really like the ease of working with aluminum, and also the “look” of using aluminum plate to make adapters. If you don’t want to take the time to use a jigsaw, these can be water-jetted, or laser-cut. Just draw it on a free design program, and then order them from a fabrication shop.

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The Battery

Many replica boardtracker ebikes I have seen in the past have mounted the battery in a faux “fuel tank” to make it easier to build. Simon wanted to use the fuel tank for storage, so he went to the extra effort of constructing a custom battery pack that would be hidden inside the V-twin “cylinders”. the best batteries for ebikes are made from the same 18650-format cells found in cordless tools.

The bare cells that make up the battery pack.

This battery has 14 cell-groups in series (14S), so it is 58V when fully charged to 4.1V per cell. Each paralleled group has six cells (6P). In order to keep the pack as compact as possible, and also evenly split between the two “cylinders”, you might notice that the 6P group at the bottom of the “V” has been split into 3+3.

Here, the cells have been covered by a layer of heavy-duty “heat shrink” sleeving, and then they will also be covered by two PVC pipes and caps.

The vertical fins on the PVC pipe “cylinder heads” were simply cut onto the sides of the plastic PVC pipe caps with a portable angle-grinder..

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The Tank

I would have been happy with any tank as well-made and beautiful as this one Simon ended up with, even if it was just a solid mass. However, Simon didn’t want that available space to go to waste, and he took the extra time to make it into a useful hollow storage locker.

The first step is making a solid Styrofoam blank, and cutting it into the rough shape.

Here, the Styrofoam core has been shaped further.

In the pic above, the core is upright, and Simon has cut a shallow groove where the top-bar would be slightly recessed into the tank. The four radial cross-wise grooves will be filled with epoxy and fiberglass to form re-enforcing ribs.

Here is the bottom of the core, and Simon is adding some thin plywood as a base for the mounts and hinges.

Gluing more plywood onto the bottom of the tank after one layer of fiberglass, and a quick look at the top of the tank after another layer.

The two pics just above are actually the second version of the tank Simon was making. The top will be nestled snugly against the frames’ top-bar, and the bottom will have mounts on one side, and a long “piano hinge” on the right side, which will open up to expose some storage space.

Almost finished!

In the pic just above, Simon has used two-part plastic automotive body-repair filler to smooth-over the outside of the tank. A thin coat would dry fairly fast, so he used several thin layers instead of a single thick layer. He then sanded and primered the finished surface.

The two cut halves of the tank.

Once Simon was happy with the outer shell of the tank, he carefully cut it in half with a thin abrasive wheel on a Dremel. Then, he scooped out the Styrofoam core.

The bottom of the mounted tank.

The left side of the tank was then mounted to the top bar with four L-brackets, and the right side was attached with the long piano hinge shown.

Here is the key-switch he installed, and a “large screen” Cycle Analyst ebike computer.

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The Seat

Simon wanted to reproduce a particular style of leather seat from the boardtrack era. He bought a wide cruiser seat from the Electra company, and stripped-off the stock cover and foam.

A used cruiser seat, purchased to provide the pan, frame, and coil-springs.

Spray adhesive and a thin gray “yoga mat” were used to create the underlying foam shape.

Simon found a large cowhide that was the perfect color and thickness.

The finished leather cover. The holes were made with a tiny drill bit on his Dremel, before he stitched the upper section to the lower part.

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The Kickstand

The 1914 Cyclone had a dual-leg stand that raises the rear wheel. This allows the mechanic to start the engine and run the rear wheel in the air, to test the cycle and work on it. Simon wanted something similar, and he also decided that he wanted to add two small skateboard wheels to the tips, so the cycle can be easily moved around with the rear wheel up in the air.

The bare custom kickstand.

A closeup of the kickstand latch, the custom seat bracket, and also the leather seat-cover bottom.

Here is this clever kickstand in the “UP” position.

The kickstand deployed.

Ebikes are usually heavier than a common bicycle, and normal kickstands will sometimes collapse, or…dig into the grass that the bike might be parked on. The most common solution is to upgrade to a “two legged” stand. This is an awesome feature that I think a lot of ebikers will incorporate, after seeing this example.

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The Final Result

Simon is still wrestling with several decisions over the color and trim, but…even if he doesn’t do anything more to it…I absolutely love the looks and performance of this eye-catching tribute to the daredevils from 100 years ago.