B. N. G. Spagthorpe:
Indomitable

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  • The Spagthorpe Indomitable was developed during the time that BNG (British National Group) owned Spagthorpe, shortly before the original family bought it back, by Wilhelm Grotonwicke Spagthorpe, AKA Willie G. Spagthorpe, as an answer to the Japanese invasion of hi-tech bikes. The market response was something less then enthusiastic and only 4 additional units were produced. (I think Malcolm Forbes had one, one blew up on the bonnie salt flats when the cooling water became contaminated, and the other two lost in the sands of time.)

    It had a driven front wheel; it was a water-cooled bike, but instead of a radiator, it had sort of a boiler affair. They ran steam lines down the front forks to a steam turbine in the front hub (the hub apparently looked sort of like a front drum brake type deal). The clever part was the centrifugal vane advance on the turbine which would adjust the vanes for maximum torque when stopped, and maximum power at speed. I was sort of skeptical, but he explained the reasoning behind it: an internal combustion engine is only about 70% efficient, with the rest being lost to heat. If you only get 50% efficiency out of the steam turbine, that’s still 15% power that would otherwise blow away in the wind. 15% power to the front wheel may not sound like much, but proportionally, it’s similar to the amount of efficiency you get out of a rear brake. So, when you look at it that way it doesn’t seem so unreasonable.

    The goal behind the driven front wheel design was similar to that of 4-wheel drive cars--increased cornering stability, and better control on surfaces with poor traction. I was concerned about the effect of the additional unsprung weight in the front wheel, but my friend just said, “Hey, it’s a Spagthorpe.” Good point.

    Apparently these bikes were never made in quantity, because the cost of British union steamfitters would have made production bikes prohibitively expensive.

    I take it that this was a completely different design from the one that had the small radial-engines, not unlike miniature versions of those used in WWII vintage aircraft, acting as both motive force and as front and rear wheels? I recall that they had several problems with this design:

    • Unsprung weight was a problem, although the center of gravity was extremely low. This model was not fitted with a center stand, a sidestand, or any kind of stand. Apparently it could easily be balanced to stand upright even on its narrow tires with no other means of support.
    • The seals around the axles had a tendency to leak gasoline. A suitable gasket material and lubricant was never developed. This ultimately led to the cancellation of the plan to store gasoline in the tires, rather than in the gas tank, more of a fuel bladder really, that doubled as the rider’s seat, although this had the advantage of the rider’s weight pressurizing the fuel system. However, the bike never idled well unless someone was sitting on it.
    • Fuel was fed through the frame down through the front forks and the rear shocks, which made the bike especially hazardous in a crash. However, one-way valves and natural suspension action served as an effective fuel pump.
    • The tires frequently melted due to high cylinder head temperatures. I know that water jackets were tried briefly, which worked as long one did not want to turn, and as long as speeds were low. Centripetal force apparently forced water high into the cylinder heads and made its return to the spinning radiators which stuck out on either side of the axles problematic.
    • At high speeds, the spark plugs were frequently thrown from their holes, which frequently entangled the spark plug wires in the spinning engine. This resulted in frequently reboring of the holes to install new plugs.

    There were several lawsuits, I recall, from pedestrians who were clipped by the rather wide (and hot) “wheels” when the machine was ridden through town. Not to mention the few that were flayed by loose spark plug wires and the still-attached plugs. A fascinating experiment, one which the march, or at least the stagger, of technology will surely eventually make feasible.

    The steam-powered front-wheeled bike was fairly dangerous and certainly too dangerous to be used in the States where its citizens have that nasty tendency to sue somebody every time they encounter even a reasonable amount of danger.

    The Spagthorpe was entered in the Ulster Trials but the local Police confiscated it, thinking it a device of the IRA.

    Spagthorpe Home Jim Groh groh@sig.cs.fsu.edu | DoD #0356 | Hog# 0437643 |new improved
    1959 XLH 900 ** 1982 FXR ** 1989 XLH 883 ** 1990 XLH 1200 | smaller sig

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