A New Measure Of Performance

This will be the last in my recent series on horsepower, torque, and how silly they both are when trying to compare bikes. But rather than simply complain yet again about how bike manufacturers fail to provide actually useful information, I’m going to help them out by giving them a solution.

You see, the bike industry has a problem that, to a certain extent, exists in the audio industry as well. If you go and buy a cheap pair of speakers or headphones, the manufacturer will try to quantify the performance statistics by listing the frequency reproduction range of the drivers – usually 50-20,000Hz.

As anyone who knows their audio gear will tell you, those numbers tell you very little – all we know is that, to a certain extent, the speakers can play really high pitched sounds up to 20kHz, and really low sounds down to 50Hz. We don’t know how accurately it will reproduce each frequency compared to the signal it is fed, but apparently that’s not important (/sarcasm). It’s kind of like quoting how many watts your speaker system in your car has. Just because it’s as loud as a pneumatic hammer doesn’t mean it sounds good.

frequency-response_sm58

A quality manufacturer will instead show a graph of the Frequency Response – from which we can learn that the SM58 microphone does a pretty good job of producing a linear response between 200 and 3000Hz, before and after which it drops off and spikes a little bit. Not much, but it’s useful to know when you’re considering spending a couple of hundred pounds on microphones.

Funny how we don’t seem to need to know this when spending several thousand pounds on a bike, isn’t it?

Yamaha R6 Dyno Chart

2007 Yamaha R6 Dyno Chart, comparing the stock exhaust system with an aftermarket one

The Yamaha R6 is a very powerful sports bike. At the rear wheel, after drivetrain losses (all manufacturer power numbers are quoted at the engine crank, and are therefore between 10-20% higher than real-world output), we can see that the R6 manages an impressive 105bhp direct from the factory.

But that figure is assuming we rev the bike all the way to 14,000RPM – and if you look at the torque curve, it’s a actually a very slow crawl up to a very low peak number. If you’re in too high a gear when you open the throttle, nothing much is going to happen at all. In stop-start traffic you’ll be slipping the clutch at 8,000RPM just to pull away, and you’ll be changing up and down the gearbox like a pinball machine.

146_06sportbike_peformance_dyno_chartshonda_corrected_torque_horsepower

The Honda ST1300 measures a lower 95bhp direct from Honda, which may seem comparatively weak for a much larger 1.3 litre V4. But if you look at the torque curve, it has more thrust off-idle than the R6 manages when screaming like a banshee.

Pulling away from traffic will be a breeze on that bike, with a much softer and progressive curve to the overall power output. The R6 will later start to pull away more and more rapidly, giving that “top-end rush” that sports bike fans find so addictive. But the ST1300 owner will find his or her bike much more enjoyable to ride in every-day, real-world scenarios, able to pull smoothly in any gear.

I had to search the internet for charts for these bikes, graphed out by tuning shops when their customers came in to have their bikes tested. But why? Is this some super-secret forbidden knowledge? Why are these charts not on the back of the box, so to speak, when you go shopping for your next bike?

Kawasaki, Triumph, Honda – they all chart their bikes a million times during development. They all tweak and fettle, desperately improving mid-range torque and chasing a linear power curve. And as the biking world moves more towards practical, torquey twins and triples over screaming race-focused inline-fours, it would seem like a no-brainer to place the dyno chart front and centre, allowing bikers to focus in on the bikes that give them the riding characteristics they’re looking for.

Put that in the marketing, Triumph!

Put that in the marketing, Triumph!

Are they afraid these graphs might prove too scary for new customers, putting them off just at a time when biking is desperately trying to lure in less traditional newcomers? Or would they help manufacturers cut through the garbage of high-rise horsepower numbers that are completely misleading when you’re finally out on the road?

Who cares how much power your engine makes just before it explodes?!

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