Offroading the GS12 for the first time ....Any tips ?

[bonox]

Sorry, Bonox - I didn't realise that you were writing from Australia; Of course gravity, or is it gyroscopes, operate the other way round there, don't they? (Must be why those All Blacks never seem to drop the ball - even when it was raining here in Lyon last Saturday.)

the only good thing you lot ever did was encourage the world to take up metric.






as for the physics, how familiar are you with corriolis accelerations? (the water in the bowl draining the other way). The acceleration is so small it doesn't have an effect - but the design of the bowl/bath etc does. And toilets on the equator don't drain without spinning - got any weird explanations for that frenchie?

 

[power2learn]

gyroscopic forces come from a sum of angular momentum. Having two wheels of equivalent rotational inertia on the same axle but spun in opposite directions result in an angular momentum sum of zero. You can try this yourself:

1 wheel on the axle spinning makes it hard to change orientation of the axle (ie gyroscopic precession inhibits the movement)

2 wheels on the axle (spinning opposite directions) shows no inhibition to movement of the axle.

The tests on bicycles used a pair of geared masses (but only one wheel of the pair touches the ground). Result? Bicycle is still stable without precession effects.

Hmm. This is very interesting. I must admit, I went away after this post thinking, yeah, but the same thing happens with kayaks - they are inherently unstable and liable to tip you over when stationary or slow moving, but feel much more secure and stable when under way.

But back to bikes - I can't think of any reason why each wheel would not exert a gyroscopic effect as it rotates at speed, and intuition would suggest having two heavy fast spinning gyroscopes to contribute to the dynamic stability of the bike, but when it comes to physics and mechanics, I trust the physicists of Berkely much more than anyones intuition .

Jones concludes: "In addition to the rider's skill and the gyroscopic forces , there are, acting on the front wheel, the centre of gravity lowering torque and the castoring forces; the heavier the bicycles load [and a GS is heavy] the more important these become." (p.40)

So it seems that it is not that gyroscopic forces are not relevant, but rather that they are one of a number of factors causing stability in two wheeled systems.

I think it is also interesting to note - Jones and the theorists he cites were only working on 'bicycles', and they observed that gyroscopic forces were significant in an unladen (riderless) bicycle, but insufficient to account for the stability of the rider / bicycle system. I presume this is because the gyroscopic forces were low compared to the gravitational effect on the riders mass as a) the wheels of a bicycle are very light, and b) they were only rotating at a relatively low speed.

It would be interesting to see how the numbers are affected by the much heavier mass of motorcycle wheels, and their much faster rotation.

But to return to the point, the article you cite above does observe: "The theory [Timoshenko & Young 1948] explains, for example, that... the faster a bicycle moves, the easier it is to ride (because a smaller steering adjustment is needed to create the centrifugal correction) and that it cannot be balanced when stationary." (p.35).

This is actually the core point I was making: whether it is because of gyroscopic effect, castor effect or some other more obscure physical property of the motorbike system, the advice to the newbie off-roader remains the same - your bike is more stable moving at a moderate pace than when crawling very gingerly at walking pace or less, so don't be too cautious, and as far as possible, keep a decent pace up on the rough stuff.

 

[cookie]

gyroscopic effect means little off road, what you need is talent.

 

[(RIP) Kaister]

what you need is to get out and do it - stop theorizing.

in the 60's they had BSA's and Triumphs - they managed..

no gyroscopic precession forces acting on their load of old bollox was there ?

 

[DrKen]

what you need is to get out and do it - stop theorizing.

in the 60's they had BSA's and Triumphs - they managed..

no gyroscopic precession forces acting on their load of old bollox was there ?

Nooooooo theorising is so important. This is the first time I have read athread on a bike forum with peer reviewed scientific paers cited as evidence. Fantastic! We could apply for a grant and have a conference - 'offroad motorcycling theory, research and practice'. Where should we go?

 

[Shep]

Nooooooo theorising is so important. This is the first time I have read athread on a bike forum with peer reviewed scientific paers cited as evidence. Fantastic! We could apply for a grant and have a conference - 'offroad motorcycling theory, research and practice'. Where should we go?

It should involve riding off road at various locations around the world, perhaps a tour even, we would have to promise not to enjoy ourselfs of course, to justify the grant

Sounds good

Shep

 

[power2learn]

D'ya know, there just might be something in this

 

[DrKen]

Multidisciplinary research is all the rage nowadays. If we can assemble a few engineers, a couple of physicists, a psychologist or two, and I will contribute as a sociologist, we could really have a lot of fun. (Which is of course the real point of conferences. Some of the best ones are actually called 'congress' and not without reason )

 

[SpyInTheCamp]

Multidisciplinary research is all the rage nowadays. If we can assemble a few engineers, a couple of physicists, a psychologist or two, and I will contribute as a sociologist, we could really have a lot of fun. (Which is of course the real point of conferences. Some of the best ones are actually called 'congress' and not without reason )

If I bring along some whisky maybe we could get some funding from the (rest of) the drinks industry too ...

Kai

 

[bonox]

Multidisciplinary research is all the rage nowadays. If we can assemble a few engineers, a couple of physicists, a psychologist or two, and I will contribute as a sociologist, we could really have a lot of fun. (Which is of course the real point of conferences. Some of the best ones are actually called 'congress' and not without reason )

*hands up for engineer*

As long as a bit of my country is included in the tour!

 

[Deano]

Just came from another fantastic ride in the desert. Not sure what kind of offroading you are planning on doing, but if its in sand then here are a few tips...

I use Tourance tires and have found today that lowering the tire pressure to 7psi in the front and 8psi in the rear is a unstoppable combination. It performed so well today that I am not going to purchase the TKC tires.

Secondly, try and keep as much weight as you can off the front wheel. Lean back and blip the throttle when you are either blimping a soft mound or dune, or whenever you are going downhill. It also helps you steer!

Finally, strap your centre stand in the up position to prevent it from bouncing up and down when going over bumps the noise is really annoying!!

Here are some pics from our trip...

 

[Brian ROSEN]

Now all we have to do is find a nice quiet beach like that!

 

[Tony F]

NuffSaid

Getting back to the original question. Note that everyone keeps mentioning Tourances, I've got Bridgestones if you have too, i'd get rid of them as soon as possible.

Been off-road(sic)* a few times now on the 1200 and it's a bit of a lump!

Tyres make a huge difference, the Bridgestones just about cope on dry tracks but as soon as it gets muddy

I've been riding "off-tarmac" on bigger four strokes for some years, as well as lots of green laning on four wheels.

*(If you are on the Plain on Byways, they are roads so technically you are not "off-road")

Most of the advice has been given... Keep it loose and relaxed, don't be afraid to use the throttle (but be prepared for the consequences), stand up (yes the bars are too low) and use the rear brake first or only if you can.

And don't go where you haven't been before, I only ride byways or UCRs that I have previously explored on my mountain bike and usually also in my Land Rover Discovery.

Now 245/75R16 BF Goodrich Mud Terrains, that's what you need for grip!!!

Good luck!

Tony

Yamaha XT250
BMW R80GS
Yamaha TT600
Land Rover Series III
Range Rover 3.5 V8
Freelander
Another Series III
BMW R1200GS
Land Rover Discovery 3.9 V8i

No not all at once! I only have the last two these days

 

['Nuffsaid]

Thanks everyone for their contributions, I went out at the weekend and .... it feels plain weird - I do not feel in control , I feel doubled over to reach the bars ( I thought I would not roll them forward until next ride ) and I really struggled to get the angle on the rear brake right .... even though I pulled it out as advised. This, combined with an incredibly twitchy throttle - funny how I never noticed this defore riding on the black stuff, made it all feel really odd - Am i alone in this ? I guess I should just keep trying - I cant wait to get it "right"

 

[Brian ROSEN]

Has this been said before?

In my humble opinion the 1200GS is probably an excellent bike off road - if you really know what you are doing; I do NOT think that it is a good FIRST bike to learn the technique, although if it is someone else's (World of BMW for instance) and you are well protected (in body and wallet) it might be worth trying.
I learnt on a 250 BSA (with a hand change incidentally) and perfected (ha,ha!) my technique on Army bikes - and wrote off quite a few in the process.
It is a bit like skiing 'off-piste' - when you get out of the cable car to go off piste for the FIRST time take a run beside a gentle green or blue slope. Don't launch yourself over the nearest precipice even if you can see others doing just that.

 

[Firebird]

The 'twitchy throttle' is probably the result of being in 1st gear. Even when going slow, snick it up in to 2nd and use the torque. I'll sound like a bag of spanners falling down the stairs, but you'll find you have much more control.

In 1st the engine breaking is so severe once you're up on the pegs that it can catch you out and pitch you forward.

 

[Deano]

yes, like firebird said, second is better! Its not a bad bike to lean on. My mate just bought a KTM 250, something you would consider a great leaners bike, and he is struggling big time... He's constantly gotta keep the thing in the power band and having to change gears because its got no torque. I start of and ride around all day in second gear... easy peasy, and its my first offroad bike too!!

Nuffsaid, yeah it does feel wierd, you gotta hold the bike with your thighs not your arms and allow the thing to move around a bit. It REALLY helps to put as much weight off the front tire as possible (by leaning back)...particularly when turning. Makes a HUGE difference!! Keep the speed going and you will stay upright. All the times I've come off, i've been going too slow.


Keep going out... you will notice that your second time will be a MILLION times better.

 

[Brian ROSEN]

That means that the FIRST time is a miliion times worse than the second time so try and use somebody else's bike for that first time!

 

[Deano]

ha ha ha ha ha!! Thats the funniest $hit!!

 

[Supervox]

Multidisciplinary research is all the rage nowadays. If we can assemble a few engineers, a couple of physicists, a psychologist or two, and I will contribute as a sociologist, we could really have a lot of fun. (Which is of course the real point of conferences. Some of the best ones are actually called 'congress' and not without reason )

Surely you will also need 'Joe "Ordinary" Bloke' who knows nothing about anything at all to use as a benchmark or baseline for all the reasearch you'll be doing ?

Well I never, the above description happens to fit me perfectly !!