Horsepower, we use it a lot, we know the numbers for our own bikes, but what is horsepower? The term 'horsepower' was first used way back in the 1700s as entrepreneurial Georgians tried to find a way of selling their newly invented steam powered machines to mine owners.
Powering the pumps that were used to clear water from mines and lift the coat out of the shaft was done by horses, so these men made claims regarding how many horses it would take to match the performance of their machines.
Although they didn't actually use the term 'horsepower', the comparison soon became the standard sales pitch. It took another half-century and the intervention of legendary inventor James Watt for the term to become commonplace and defined. In the late 1770s, Watt's genius revolutionized the construction of the steam engine. His new machine was far more efficient than the old Newcomen engine at pumping water out of mines, but he needed a term to convince the bosses at coal mines that they should invest in his engine.
At this point, the historical records are split in their opinions on exactly how Watt calculated a horsepower, but basically, he estimated how much weight an average pony could lift and over what distance in a minute and came up with a figure of 33,000 feet pounds a minute. Which became known as 'one horsepower'. Now, this is all very well and good, but after Watt's genius heralded in the industrial revolution, we have moved on a bit from horses, so how does this figure equate to your motorcycle?
Over the years, the term horsepower became an industry standard for power, but as you might have noticed, it's measured in foot-pounds, a figure we're more used to seeing to measure torque. The fact is that horsepower and torque are directly related, and horsepower is a product of torque. Or to put it simple, to find horsepower, you have to find torque, then do some more calculations.
So how do you find torque? That's where a dynamo-meter comes in. The 'dyno' measures how much load your engine can create. Inside a dyno is a huge, and very heavy drum. When your motorcycle is strapped to it, the force required to accelerate the drum by your motorcycle's rear wheel is measured by the dyno and converted into power and torque charts. If you really want to know you can work out your motorcycle's horsepower by multiplying its torque by its revs at a certain point, then dividing it by 5,252. An interesting fact is that because horsepower is a product of torque, the two lines on a dyno printout will always cross.
So now you know what horsepower is, why is it important? To be truthful, it isn't. Much like a mile or a kilometer, horsepower is simply a way of comparing a set measurement. It's an industry standard, but that doesn't stop us wanting more of it.