Blog: How much horsepower do you really need?

Motorcycling will always be one of those things where mostest is best. Forget octane ratings and rpm, we should measure biking by TPM - testosterone per minute. Imagine if we approached life in the same way, we’d all be wearing trousers with ten legs – accepting that while we didn’t actually need the additional eight, ‘it’s good to ‘have the extra fabric to get me out of trouble’ Maybe we’d pay extra too for ‘Flaption control’ to stop those extra legs causing aerodynamic drag when we ran faster than 5mph.

A few years back I was involved in a fascinating feature demonstrating how much of our bike’s horsepower we actually used. We took four very different bikes; a Suzuki GSX-R600, Yamaha XJR1300, Honda ST1100 Pan European and Harley V-Rod, fitted them with state of the art datalogging equipment and measured how much throttle was used and how much horsepower around a 50-mile blast on our favourite roads. The bikes were chosen for their difference in character, but also because they all made around 100bhp.

To make the test more interesting we used the most talented rider in Corby – a racer and stunt rider who was more likely to use more throttle than we were.

The results were fascinating. The XJR1300 was the only bike to use more than 70bhp, peaking at 89bhp, but only for about ten seconds in the 48 minutes it took to complete the route. The Pan European had the highest average power-used figure at 43.8bhp and the GSX-R600, being ridden by a fast racer averaged just 29bhp and never got above 50bhp once.

He was as surprised as we were, reporting that he’d had the Suzuki’s needle in the red for much of the time. Thing is… you can hit the red line on any bike at far less than full throttle. Try it next time you’re out – hold the throttle about a third open in the lower gears and see how quickly you hit the limiter.

And that’s where it gets confusing because revs don’t equal power unless you’re at full throttle. Why does this matter? Well, thank you for sticking with me for 365 words, here’s the point.

A few weeks back I was reading a thread on social media about sports bike electronics. Opinion was split as to whether they were a good or bad thing and it didn’t take long for some online hero to explain how ‘now bikes like his make 200bhp, they’d be unrideable without all these electronics’.

I might have missed something here, but back in the bad old days when a decent sports bike only made 180bhp and had no electronic restriction I don’t remember every ride being peppered with cartwheeling R1s and Fireblades highsiding themselves into oblivion. Most crashes not involving a SMIDSY car driver had a rider misjudging a corner, hitting the front brake, which stood the bike up and ran them wide into a ditch. Now it’s possible that cornering ABS might have saved that, but traction control would be irrelevant because in that crash, the throttle is shut.

The boffins that did our 100bhp feature all those years ago explained what happens very clearly. On the road you use your throttle (and therefore power) to accelerate up to a certain speed and then back off, holding a steady throttle to maintain that speed. It needs a certain amount of power to achieve that speed, but once there, you only need a whiff of throttle to overcome the airflow and maintain momentum. Arrive at a corner and you need to slow down. Once through the corner, you accelerate up to speed again.

The reason our heavy tourer used almost twice as much power as the sports bike is because at every corner on our very twisty route it had to slow down more (because it was heavy and handled much worse) and consequently, then had to accelerate harder to get back up to speed, which used more power.

The good-handling sports bike had to slow down much less for the corners and so needed less power to accelerate back up to speed. So, in order to use our bikes most efficiently, Honda should be making 200bhp Pan Europeans and 60bhp Fireblades.

Which is, of course, exactly what we are getting with the latest generation of traction control. TC is a metaphor for power restriction. It allows a manufacturer to build a 200bhp motorcycle to satisfy the marketing dept and their customers’ machismo trouser requirements, but then electronically restrict it in order that, should anyone who buys it actually be clumsy enough to use more than half that power, the restrictors will cut in and make up for their lack of talent. Not only that, but they can charge us extra money for the privilege. Genius.   

On track, of course, the situation is very different. Our boffins explained that any racer or wannabbee track day hero - safe in the knowledge that all they have to do is get to the next corner faster than everyone else - should be aiming to use either full throttle or no throttle all the time, anything else is the behaviour of a dithering loser. And that’s where the electronics come in. Because if you or me, with a lifetime of smoothly using 29bhp on the road to go faster than we ever dreamed, suddenly gets giddy and finds the guts to unleash the full potential of our engines, then, yes, maybe, if that potential is 150bhp-plus, we might just need an electronic version of ‘perhaps this throttle should go the other way now’.

What’s needed here is a bold manufacturer, prepared to build a bike that makes relatively low peak power, but delivers it in a way that helps us use more of it. Funnily enough a mate of mine is currently looking to buy an ancient Honda VFR400. Imagine if there was a modern version of that bike? A 500cc V-four making 80bhp and weighing 140kg. sounds brilliant to me.

And a trip the other week on KTM’s new 790 Duke showed it to be exactly that kind of bike Not too much power, but all delivered in a huge great slug of drive in a chassis that made life feel very, very exciting. If only I can find my turbocharged, ten-nibbed, rainbow-inked Titanium biro I could sign on the dotted line right now.