Turning Circle Question.

[copemech]

Interesting...

Yes it will turn tighter. But only by a couple of mm. Leaning the bike further into the turn will make it turn much tighter.

6mm will make the steering angle steeper buy approx 0.16deg. You may as well be talking about nothing and tyre pressure or spring settings will have more effect on steering head angle.

It is likely to effect the feel of the handling of the bike and how the front would either tuck under or plow forward. But again tyre pressure and spring settings will effect things more

The biggest difference i found is that the bars will be lower which suits some riders more.

And you see there Jon, Ralphy has done us a calculation on the angular change, which just goes to support my theory that it is basically neglidgable.

Now I shall expound upon my "Little Man in the Boat" theory(it is Friday night), just for Jon!

You see, the boat has to displace a certain amount of water to support itself and the occupant. Consider the springs on the bike just like the water.

As the position of the man changes, so does the waterline of the boat. The changes of the weight of the man shall have a profound effect upon how the boat sits in the water. The same effect applies to just how much angular difference is changed on the bike. Not only that, but how much weight is applied upon the tire. Grip requires friction, friction requires force, force requires weight. And once the grip is exceeded, you will no longer turn(tire will push or skate).

You need a MOTORBOAT!

Recall them motorboat sounds when you are thinking about the little man in the boat?

Well, you see that the motor will automatically lean the boat toward the inside of the turn when instructed to do so. As our little boat motor(the rear wheel) does not turn sideways, WE are the ones that have to supply the correct lean angle for the turn. It is like cheating! As we can artificially influence the natural lean angle to effect the turn, at least within certain limits of balance.

As Scorpa3 must obviously ride a Scorps, which has in itself an extreme turning angle, more than most anything out there, yet still having problems, I doubt a change in the fork height will give you much change. You need to be think more about where the man is in the boat!

Now , can you make that little sound of the motorboat? Keep your inside arm straight man! And make the sound!

I need more beer now!

[jse]

And you see there Jon, Ralphy has done us a calculation on the angular change, which just goes to support my theory that it is basically neglidgable.

Now I shall expound upon my "Little Man in the Boat" theory(it is Friday night), just for Jon!

You see, the boat has to displace a certain amount of water to support itself and the occupant. Consider the springs on the bike just like the water.

As the position of the man changes, so does the waterline of the boat. The changes of the weight of the man shall have a profound effect upon how the boat sits in the water. The same effect applies to just how much angular difference is changed on the bike. Not only that, but how much weight is applied upon the tire. Grip requires friction, friction requires force, force requires weight. And once the grip is exceeded, you will no longer turn(tire will push or skate).

You need a MOTORBOAT!

Recall them motorboat sounds when you are thinking about the little man in the boat?

Well, you see that the motor will automatically lean the boat toward the inside of the turn when instructed to do so. As our little boat motor(the rear wheel) does not turn sideways, WE are the ones that have to supply the correct lean angle for the turn. It is like cheating! As we can artificially influence the natural lean angle to effect the turn, at least within certain limits of balance.

As Scorpa3 must obviously ride a Scorps, which has in itself an extreme turning angle, more than most anything out there, yet still having problems, I doubt a change in the fork height will give you much change. You need to be think more about where the man is in the boat!

Now , can you make that little sound of the motorboat? Keep your inside arm straight man! And make the sound!

I need more beer now!

Wow. I am now totally confused, yet I feel strangely enlightened. I agree, time for another beer......

Jon

[feetupfun]

Copemech's explanation is very good and even works without a beer to help. The man in the boat is definitely what makes the boat.. er...bike turn. That is why bikes are more fun than 4 wheelers in my opinion. There is way more skill needed to do the turns well on two wheels.

Whoever it was that asked the question first, you can do an interesting experiment on a dusty surface that will answer your question perfectly - actually any surface that will leave a visible track of the front wheel of your trials bike.

Part 1

Ride the bike in a full lock turn with standard fork height. Measure the diameter of the front wheel mark.

Part 2

Raise the forks as high as you want in the clamps and try it again. Again measure the diameter of the wheel mark (it might be a bit smaller diameter than part 1)

Part 3

Put the forks back to standard position and ride the turn with the bike leaning over into the turn about 30 degrees and your inside foot just above the inside footpeg (to make sure you have all your weight on the outside footpeg). This time the turn diameter will be much smaller than in parts 1 and 2 and you may not have even touched the steering angle stops in the process.

Good clutch control, rear brake control and footpeg weighting is how to make a trials bike turn amazingly tight.

If you ever find the front wheel sliding sideways on a flat or soft surface, that is a clear message that rider technique is in need of improvement.

[scorpa3]

I'm certainly not wishing to make the SY250 turn any tighter and I can bounce the front around on that ok. No, it's my DRZ400 that I need to turn tighter, I only really use it for LDT's and setting out events (now that much of our local trail riding has been made restricted.)

I've ground back the lock stops until the fork tubes are just about touching the tank on full turn, so altering the ride height is the only other thing to try. Suspension travel isn't an issue and LDT's generally don't need bikes with metres of ground clearance but we do come across tight turns a lot..... for a trail bike that is!

Thanks for everyones input.

[nzralphy]

Ohhh now we see what you are trying to do.

Well I've had my beer and have figured out what you should do.

You need to make the wheel-base shorter. Try this.... cut the very front and very rear ward facing tyre knobs off. It should shorten the bike up a bit and will work brilliantly )

More beer.

[steveo]

Ralphy you are a Knob, everyone knows the wheel base is different to the length of the bloody bike, how many beers have you had. If you want a shorter wheel base tighten your chain more.

[zippy]

steveo Posted Today, 08:09 AM

Ralphy you are a Knob, everyone knows the wheel base is different to the length of the bloody bike, how many beers have you had. If you want a shorter wheel base tighten your chain more.

UUUMMM, actually if you want a shorter wheel base you would have to loosen the chain, by tightening the chain you move the rear wheel away from the front wheel. How many beers have you had.

Hey Scorpa3,

Just give it a try hopping that DRZ400, It's all the same techniques just a bit heavier, yea that's it, should be easy

[neo]

And the tractor won't complain if he rides a different tractor tomorrow.

Best of balance (is what's really needed for tight turns).

Neo

[feetupfun]

I'm certainly not wishing to make the SY250 turn any tighter and I can bounce the front around on that ok. No, it's my DRZ400 that I need to turn tighter, I only really use it for LDT's and setting out events (now that much of our local trail riding has been made restricted.)

I've ground back the lock stops until the fork tubes are just about touching the tank on full turn, so altering the ride height is the only other thing to try. Suspension travel isn't an issue and LDT's generally don't need bikes with metres of ground clearance but we do come across tight turns a lot..... for a trail bike that is!

Thanks for everyones input.

If you like hopping the front of the Scorpa, why not just learn to hop the DRZ instead of all that modification stuff?

I've done lots of course setting for Pony Express and Enduro events on a similar bike to your DRZ and found that when you get caught in a very tight spot the old fashioned balance-the-bike-on-the-rear-wheel-and-pivot-it-around-to-the-new-direction works very well. It is easiest if you pivot towards the left so you can hold the rear brake on while your left foot stays on the ground.

Edited September 14, 2008 by feetupfun

[scorpa3]

If you like hopping the front of the Scorpa, why not just learn to hop the DRZ instead of all that modification stuff?

I've done lots of course setting for Pony Express and Enduro events on a similar bike to your DRZ and found that when you get caught in a very tight spot the old fashioned balance-the-bike-on-the-rear-wheel-and-pivot-it-around-to-the-new-direction works very well. It is easiest if you pivot towards the left so you can hold the rear brake on while your left foot stays on the ground.

Hopping a trials bike is something you can learn, hopping a DRZ400... now that I'd like to see!

If I can get the bike to turn just a little tighter by using "all that modification stuff" then it will be time and effort well spent.

"Foot stays on the ground" is exactly what I am trying to avoid here. Remember, you loose marks for every foot down.

[copemech]

Ummmmhhhh! This should do the trick!

A little trick!

Oops , scroll down to the post 19!

Edited September 16, 2008 by copemech

[biffsgasgas]

Have some one less experienced than you do this.

It would reduce the rake.

Make sure its a done deal by adding something like this.

Best of luck!

--Biff