Under ideal conditions, each part would need its own temperature range to perform most efficiently but, like everything in this sport, the balance between performance and wear is very delicate. The parts of the bike are designed to resist high temperatures and to operate within an ideal margin but even then they suffer wear and tear. You only have to look at the tyres, which have a temperature of around 100°C in order to have optimal grip. But when they are on asphalt that can reach a temperature of over 50°C they gradually wear down.
The temperature of the tyres is high, but that’s nothing compared to what the carbon brake pads reach at full capacity. While the calipers can reach 200°C, the optimum operating range for the discs and pads ranges between 200°C and 800°C. Now that’s hot, isn’t it?
The suspension doesn’t get as hot, especially the front suspension, which is normally a little above ambient temperature. The rear suspension can get much hotter, reaching 70°C. It’s very important to take measurements of the ambient temperature when adjusting the suspension, since the viscosity of the oil inside varies according to the day’s heat.
The fuel cannot, according to the regulations, be more than 15°C below the ambient temperature. At 15°C, 1 litre of fuel weigh 0.75 kg, while at 25°C the same weight corresponds to 1.01 litres, so that the hotter the day, the less fuel you can put in the tank. This phenomenon occurs because liquids expand with heat and contract with cold. Dorna measures the ambient temperature one hour before the race to decide what temperature the fuel can have.
The rider must remain around 36.5°C at most, especially if we want them to finish the race in good health! During hotter races, cooling systems may be used inside the suit, like those used by astronauts.
Without a doubt, the component that reaches the highest temperatures is the engine, where the flame front normally reaches 1800°C and can reach 2500°C. These temperatures are only reached at ignition point but they are enough to heat the heads of the pistons to over 250°C and the cylinder walls to over 200°C. The intake valves get to 250°C but the exhaust valves are over 600°C, as the exhaust gases easily exceed 700°C.
The bikes have numerous sensors to measure the temperature at some 10 points. Because of the cooling system and Repsol lubricants, the components can remain at ideal temperatures, allowing the engine to perform at its best. Honda and Repsol work together to get the best results in competition.