http://www.motorcyclenews.com/MCN/News/new...wheel-drive-r1/
Ohlins’ 2WD project manager reveals: it was faster dry or wet, suffered only a 2.5bhp power loss, and that there were four manufacturers who had Ohlins 2WD-equipped mules.
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Is it true the system only works when the rear wheel is slipping?
Yes. But the only time you have no rear-wheel slip on motorcycle is when you are pushing the bike. If you are riding, even at a constant speed, then you have a small slip. Before rubber transmits any drive at all it deforms. At 80kmh you have maybe 0.5% slip. At full throttle at 200kmh you have as much as 5% slip. At 5% spin there is roughly 160bar pressure in the system [system is pre-pressurised to 2-3 bar at rest].
In a corner, because of the different width in tyres front and rear, the rear wheel rotates faster than the front and this pressurises the system too, sending more power to the front. It works as hard at a constant speed in a corner as when accelerating at full throttle in a straight line. The effect is to drag the bag into the apex in a very different way to a rear-wheel-drive [RWD] bike. Turning the throttle in a bend on a RWD bike causes the bike’s front to lift and the bike to understeer. With 2wd the behaviour is completely different – the more you accelerate the more tightly the bike begins to turn.
What were the performance benefits?
Stability and cornering. Accelerating hard in a straight line the 2WD bike tracked straighter, with less chance of wheelying. But if you did provoke it into a wheelie it was much more easy to control – the spinning wheel creates gyroscopic stability to balance the whole bike. In the corners testers found they could accelerate harder round corners with none of the understeer that would normally cause. Just overcoming the rolling resistance of the front wheel helps the stability in all conditions. The R1 was 5 seconds faster in the wet at Kelskoga track. But it was between 1 and 2 sec faster in the dry too. The press has focused on advantages for novice riders, and this is true off-road. But on-road the more experienced you are the more benefits you can exploit. The more aggressively you ride it, the closer you dare to be to the limit, the more you stand to gain.
Which other manufacturers were interested?
Four manufacturers from Japan and Europe were very interested. We visited their factories to demonstrate the 2wd R1 and TT600R, and we came away with some of their machines to convert to 2wd for them to evaluate – everything from sportsbikes to tourers.
What was the response from the manufacturers?
Most of their test riders were impressed by the system on the R1. Most were going faster in the dry as well as the wet thanks to increased corner speed. But it altered the bike’s character from very crisp and urgent, into something more relaxed. Not slower, but easier to drive through corners and less ‘frisky’. It was a little heavier to turn in chicanes.
By 2004 we had the manufacturers’ bikes ready for evaluation – a tourer, a sportsbike equivalent to the R1, an adventure bike and another off-road bike. We thought the system added performance to all of them. They then took them away and as far as I know they still have them. Waiting to hear back was like waiting to hear from a girlfriend who has gone away. Unfortunately we heard very little.
What went wrong?
In 2004 we produced with Yamaha the WR450 2-Trac, with a run of 250 units. But demand was low because the price of such a limited run is high, and it was never homologated for the road. It was very frustrating to watch that bike fail. We continued to develop the technology for two years, until 2007, and had a new generation ready. But after the 2-Trac there wasn’t the demand. If that bike had succeeded we would have two-wheel-drive Yamahas and perhaps from other manufacturers today.
...
Ohlins’ 2WD project manager reveals: it was faster dry or wet, suffered only a 2.5bhp power loss, and that there were four manufacturers who had Ohlins 2WD-equipped mules.
...
Is it true the system only works when the rear wheel is slipping?
Yes. But the only time you have no rear-wheel slip on motorcycle is when you are pushing the bike. If you are riding, even at a constant speed, then you have a small slip. Before rubber transmits any drive at all it deforms. At 80kmh you have maybe 0.5% slip. At full throttle at 200kmh you have as much as 5% slip. At 5% spin there is roughly 160bar pressure in the system [system is pre-pressurised to 2-3 bar at rest].
In a corner, because of the different width in tyres front and rear, the rear wheel rotates faster than the front and this pressurises the system too, sending more power to the front. It works as hard at a constant speed in a corner as when accelerating at full throttle in a straight line. The effect is to drag the bag into the apex in a very different way to a rear-wheel-drive [RWD] bike. Turning the throttle in a bend on a RWD bike causes the bike’s front to lift and the bike to understeer. With 2wd the behaviour is completely different – the more you accelerate the more tightly the bike begins to turn.
What were the performance benefits?
Stability and cornering. Accelerating hard in a straight line the 2WD bike tracked straighter, with less chance of wheelying. But if you did provoke it into a wheelie it was much more easy to control – the spinning wheel creates gyroscopic stability to balance the whole bike. In the corners testers found they could accelerate harder round corners with none of the understeer that would normally cause. Just overcoming the rolling resistance of the front wheel helps the stability in all conditions. The R1 was 5 seconds faster in the wet at Kelskoga track. But it was between 1 and 2 sec faster in the dry too. The press has focused on advantages for novice riders, and this is true off-road. But on-road the more experienced you are the more benefits you can exploit. The more aggressively you ride it, the closer you dare to be to the limit, the more you stand to gain.
Which other manufacturers were interested?
Four manufacturers from Japan and Europe were very interested. We visited their factories to demonstrate the 2wd R1 and TT600R, and we came away with some of their machines to convert to 2wd for them to evaluate – everything from sportsbikes to tourers.
What was the response from the manufacturers?
Most of their test riders were impressed by the system on the R1. Most were going faster in the dry as well as the wet thanks to increased corner speed. But it altered the bike’s character from very crisp and urgent, into something more relaxed. Not slower, but easier to drive through corners and less ‘frisky’. It was a little heavier to turn in chicanes.
By 2004 we had the manufacturers’ bikes ready for evaluation – a tourer, a sportsbike equivalent to the R1, an adventure bike and another off-road bike. We thought the system added performance to all of them. They then took them away and as far as I know they still have them. Waiting to hear back was like waiting to hear from a girlfriend who has gone away. Unfortunately we heard very little.
What went wrong?
In 2004 we produced with Yamaha the WR450 2-Trac, with a run of 250 units. But demand was low because the price of such a limited run is high, and it was never homologated for the road. It was very frustrating to watch that bike fail. We continued to develop the technology for two years, until 2007, and had a new generation ready. But after the 2-Trac there wasn’t the demand. If that bike had succeeded we would have two-wheel-drive Yamahas and perhaps from other manufacturers today.
...
