The Drysdale 2x2x2:

Riding the Drysdale 2x2x2 is certainly different - various descriptions were :

- Like riding a jetski (referring to the Kawasaki stand up type)- you have to use the handlebars more than you would normally.
- Like sex with a condom - similar to normal but not the same! 

These sensations resulted from the design decision to have normal handlebar lock for full lock at both wheels.  In other words 45 degrees of handlebar turn gave 22 degrees of lock at each wheel resulting in a better turning circle than a conventional bike at 45 degree handlebar turn.

But it was the progression to this full lock that resulted in an 'odd' feel to it - intially (when the rear wheel is 'frozen') you need to turn the handlebars twice as much as you would normally.  After about 5 degrees there is a period where you require about the same handlebar lock as normal then for the last 10 degrees or so you get more turn than normal for the same handlebar movement.

This may sound like a nightmare but actually was quite easy to get used to.  The plan was to alter this on later versions so that the handlebar to front wheel ratio was closer to 1:1 (but still constant).  As you know- I am only using this set-up on my 2WD bikes and the conclusion I came to was that a 2WD doesn't need as much steering lock as a conventional bike.  It does obviously for slow speed manoeuvring - but at speed there is no need for any degree of lock as a 2WD does beautiful 'zero lock' 2 wheel slides. The slow speed stuff is just something you would have to put up with.

What is a 2WD motorcycle like to ride ?  Motorcyclists normally control their machines with a lot more physical input than their car driving counterparts and hence most motorcyclists will claim that 2WD is variously either unnecessary and/or will spoil the 'feel' of a motorcycle.

I don't think either is true.  My 2WD is a 250 in a reasonably low state of tune - combined with the smoothness of the hydrostatic drive it was almost impossible to get any wheel spin in even the slipperiest conditions.  The 2 wheel steer added to this sensation at low speed as at near full lock both wheels followed almost the same track.  You can use full lock and full throttle in a mud patch and as you turn tighter and tighter the bike will actually highside you every time!  This is due to centripetal force rather than the slip-and-bite highside of a roadracer.

The problems with braking meant that not a lot of high speed testing was done but the 2WD definitely feels more stable in a straight line.  You can feel the front wheel pulling- hard to explain but it feels more 'neutral' than a 1WD.

Sam Xereb's CR500 2WD:

To backtrack a little, Sam Xereb lives in Traralgon, (a few hundred kilometres East of Melbourne Australia) and in 1993 he built a 2WD bike based on a Honda CR500 motocrosser.  Much of the original bike remained but the front end was replaced with a 'stay-arm' and single upper pivoting triple clamp (not unlike the Saxon/Motodd Laverdas and later BMW Telelever) which allowed the implementation of a two-chain drive to the front wheel.  Front and rear wheels were the same diameter with the front undergeared by 5% compared to the rear and driven through a one-way clutch allowing the front wheel to freewheel when coasting but lock up under power- much like a pushbike.  Back to the story…..

Sam's 2WD is a different story altogether- it is without a doubt the wildest thing I have ever ridden.  This is accentuated by the fact that it is a 500 cc 2 stroke with no flywheel (removed when the crank was shortened to allow the drive to be tucked in closer) making the power delivery instantaneous. I rode it on a bush track with an embankment on one side and drop off on the other -not ideal on a dirtbike with 25 degrees of steering lock!

On the first ride I didn't like it at all- the front (18in) knobby was a fairly wide pattern and you could feel the bumps as it stepped from one knob to the next- I was just being too cautious.  I took a second ride- this time with a little more aggression- and became a convert.  As the rear starts to break traction you can feel the back end come out and you opposite lock as per usual (whilst worrying about the limits of the lock).  With a little more wheelspin the front starts to drive (5 % undergeared remember) and all of a sudden the handlebars come back to the straight ahead position and you are doing a perfect 2 wheel slide with the bars straight ahead. Amazing!

Opposite locking into a slide is a natural (and fun) reaction on a conventional bike, it is hard to believe but 2 wheel sliding with no lock is also a completely natural feeling. To look at someone else doing it looks just like the 4WD rally cars- perfect slides with no lock. Angles of lean can be much greater when cornering in the dirt as you can pull the bike down faster with the front driving- and also pull the bike out of the turn as well.

Whilst most people can see the advantages of 2WD in the dirt- I also believe that it would have a marked effect on a roadrace bike's handling as well.  Before we took the CR 500 out to the bush tracks Sam warmed it up in the street outside his house- I have never seen a bike come around a corner like that on bitumen in my life!  Some minor advantage may be gained in a straight line but it is in corners that I believe 2WD roadracers would shine- imagine the confidence that would be gained from knowing that the back end can not slide out far enough to cause a highside.  I could see that a return to harder compound tyres may even be desirable to encourage wheelslip to engage the 2WD instead of just using it as a 'backup'. Of course you can still 'lowside' a 2WD bike but I think there would be much more warning than either a lowside or a highside on a conventional roadbike.