Guest Blog: Mat Oxley - MotoGP’s aerodynamic advances: wings are creating more wings

MotoMatters.com is delighted to feature the work of iconic MotoGP writer Mat Oxley. Oxley is a former racer, TT winner and highly respected author of biographies of world champions Mick Doohan and Valentino Rossi, and currently writes for Motor Sport Magazine, where he is MotoGP correspondent. We are featuring sections from Oxley's blogs, which are posted in full on the Motor Sport Magazine website.


MotoGP’s aerodynamic advances: wings are creating more wings

What’s the story behind the fuel-tank wings appearing on MotoGP bikes? It’s all about the extra grip offered by the latest aerodynamics

MotoGP riders pull 1.7g on the brakes, which sounds like nothing when Formula 1 cars pull 5g. But an F1 driver is strapped into his car with a seven-point harness, similar to those used in fighter jets. A MotoGP rider holds on by curling his hands and fingers around the handlebar grips.

In fact, this isn’t enough, so riders use their thighs, feet and backsides to help grip the bike, by gripping the tank like a vice with their knees, digging their feet into the footpegs, (at least until they dangle a leg) and jamming their backside against the seat hump; basically trying to wedge themselves into the bike.

It’s a precarious grip, however, because the rider’s only proper grip is with his (or her) hands, which can work like a pivot, so if he’s not careful he will get catapulted over the handlebars when he hits the brakes.

I know this because I’ve been that idiot, launching myself over the screen when I tested Mick Doohan’s Honda NSR500 at Catalunya, after the 1995 Grand Prix of Europe. Usually teams equipped their bikes with steel discs for journalists unaccustomed to the brick-wall-effect of carbon brakes. But sometimes they left the carbons in place.

That day Doohan’s crew chief Jeremy Burgess and his mechanics fitted carbons. I’m sure I could hear their sniggers as Alex Briggs pushed me off down pit lane.

Riding 500s was always a brain-frazzling experience – your brain literally struggling to keep up as you arrived at the next corner seemingly before you’d left the last.

After a few laps – tyres warmish, brakes warmish – I arrived at Turn Nine, the corner before the site of Sunday’s Catalan GP disaster. I braked hard, the front forks compressed, the rear shock extended and my backside came off the seat like I’d hit the ejector button. Then my feet came off the footpegs. To my horror I was being hurled forward, over the handlebars, pivoting over my wrists. I was totally out of control, doing maybe 120mph.

Read the rest of Mat Oxley's blog on the Motor Sport Magazine website.

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Am I the only one who remembers that road bike stopping distances have not changed in decades?

So, I went and checked.  I found a road test in Cycle Guide from April 1980 where they tested a Kawasaki Z1-R.  In the test data they provided some comparitive stopping distance (60mph-0):

  • Ducati Darmah: 120ft = 1.08g (The first thing I noticed when looking at one is the long wheelbase)
  • Suzuki GS1000S: 124ft = 1.04g

Then I looked up the numbers for modern superbikes (pick your favourite).  The best are around the same at 120 to 125 ft.

But we now have infinitely better brakes and tyres - what gives?

The answer is simple.  The limiting factor in braking with any modern sports or race bike (in a straight line on a good surface) is geometry, specifically the tipping point. As you decelerate harder, the weight of the bike is transferred onto the front wheel. Once all the weight is on the front wheel, you are at maximum deceleration. Brake harder and you will risk doing a somersault like Mat almost did.  Modern bikes do not brake harder than the ones of 30 years ago for the simple reason that they have the same geometrical limitations.  The tyres on all of them are good enough to do a stoppie, the brakes are all good enough to lock the front wheel.

So, if it is geometry limited, how come MotoGP bikes can brake at "1.7g"?  The simple answer is that they don't. Looking at turn 12 at Austin, a long and flat braking zone, according to Brembo (https://www.brembo.com/en/company/news/motogp-americas-brembo-brakes) a MotoGP bike 12 decelerates from 339 to 67 in 6.3 seconds, which equates to 1.22g (1g = 35.3 kph/sec).  This is about the highest ever seen.  There are of course higher instantaneous values, but in the context of Mat's article (physical effort of repeated long braking zones) 1.2g is about it.  The fact that MotoGP bikes can do 1.2g (as against the 1.05g of road bikes) is probably due to the higher speeds (aerodynamic drag at 300 is serious) and a bit of downforce.

 

Total votes: 11

Ah, the Z1-R. Back in the day in my neck of the woods, if you had one of those and were still walking 3 months down the line, you were a local hero. In fact you were a hero even if you weren't still walking. A beautiful but beastly machine.

Total votes: 3