Kevin Cameron
Shouldrace bikesbe purpose-builtor heavilybasedon productionbikes?
Should race bikes be purpose-built? Kevin Cameron looks at the longstanding argument.
When the Isle of Man TT road races resumed in 1920after the Great War,the general assumption was that this was still a test of endurance among well-prepared production bikes - literally a Tourist Trophy event. If primitive belt-rim or caliper brakes functioned poorly, too bad! It would be un-sporting to fit nonproduction brakes that actually worked.
Yetit was also clear that success on the Island sold a lot of motorcycles, such that sourpuss makers like Triumph and BSA,normally devoted to selling lowpriced utility bikes, were tempted to give it a try.
In engines, the sharp point of technology was overhead valves. But Laurence Pomeroy's dictum applied in 1920: "The first instance of novel principle is invariably defeated by the developed example of established practice:' A side-valve Sunbeam won the Senior TT in 1920, despite Douglas's head start with OHV (they'd built one in 1913) and AJS'scertainty that OHV was the future. Alec Bennett's 1922 Senior win on a Sunbeam would be the last in class by a side-valve.
The following year Douglas got it right and the revolution appeared unstoppable as their bikes were 1-2-3-4 on the first lap. One by one they stopped, leaving local man Tom Sheard to win on the highrevving OHV Douglas flat twin.
It was tempting to take the moral high ground by running useless stock brakes and flexy pre-war chassis in the TT, but it was becoming clear that misguided morality did not win races. 'Pa' Norton famously threatened to fire any rider who raced with other than the jerky, short-travel Druid girder fork.
But riders see clearly what better ideas can do. Graham Walker fitted a longer-travel Webb fork with friction damping - and went faster. One by one, the other riders followed his example.
When Walter Moore was hired to make a winner of Norton's OHV 500, he saw it was crippled by nearly useless stock brakes. As British Hub, the usual supplier, could do nothing before the TT, Moore adapted brakes from Ford cars.
When crankpins wallowed loose in soft cast-iron stock engine flywheels, what was a moralist to do? No new bikes would be sold by crowing that their parts, proven inferior in performance, best fit the spirit of the rules. This made the choice a simple one: either race to win or don't race at all. Cast iron flywheels were replaced by heat-treated carbon steel equivalents.
AJS and Velocette saw the value of overhead cam (OHC, but it took them time to make it work. Douglas and Sunbeam both made OHC experiments, but without success. To make bikes finish races, a lot of testing was necessary, and there was a need for development engineers with racing experience. Hire one of the top men and, like it or not, your results improved. Racing was no longer just sporty flat-cap riding on standard bikes. When you fixed what broke in this process, your motorcycle naturally evolved into a purpose-built racing machine.
The shortcomings of drip-feed total-loss oiling drove design toward full pumped recirculating oil systems. A total-loss rider, looking back and seeing no smoke, knew it was time to 'give 'er a shot' of oil with the hand pump. Engines rejected such cretinous schemes by tightening and seizing at speed.
First one maker and then another had spurts of TT success. Douglas had no future in racing because there was no way to cool their rear cylinder, sheltered as it was behind the crankcase and magneto. Sunbeam and Rudge had short-term success too, but it was becoming clear that winning required designing to win - not 'careful assembly' of warmed-over production machines with useless brakes and frames that snapped.
Norton eventually accepted this wholeheartedly and the resulting long list of wins drew criticism that they had 'ruined racing'. In 1931, once they'd got their OHC 500 and 350 performing properly, Nortons were first, second and fourth in the Junior, and 1-2-3 in the Senior, ahead of two Rudges.
Did Norton ruin racing? Experience of the present day in MotoGP and World Superbike tells us clearly that they did not. What they did was build the best bike possible under the rules in force. If anyone
'ruined' racing, it was the rules-makers in failing to set limits like those set out in detail for WorldSBK.
Yetbecause this was all happening for the first time in the sport we can't frown too darkly at the rulesmakers either. The 'spirit of the rules' was made clear in 1911 when pedalling gear was banned and multi-speed gearboxes were deliberately encouraged. The role of racing was to bring forth technologies that would raise the capability of the motorcycle for all users.