ESE's works engine tuner

[Drew]

Yip, and tried to add as much as we can.
I actually thought it was an interesting thing to discuss.
Given late model RS125s and TZ125s tend to show this as well.
The GPR frames feel great on track.
Streamroller, your only 3rd in NZ (two years in a row) what would you know.
And don't worry about Glen Williams SVR650....

Wobs post above makes good sense, I can imagine that the more mass (weight) and more power - loads up the front with too much anti squat and if front end is not setup to deal with it then it will all go pear shaped.

Owell we will stay away.

It's not the front that it goes pear shaped at. The rear lets go in a hell of a hurry, because the suspension isn't working due to the torque fighting it. So there's no give and when it hits a bump the wheel leaves the ground.

The distance between the two sprockets is at it's greatest when the swingarm pivot and sprocket centers are all in a straight line. When you put the rear sprocket lower than that straight line and apply the gas, the torque is trying to pull that sprocket forward by shortening the distance more as the swingarm further extends.

Loading a tyre more is the goal, bump compliance is the unfortunate requirement for suspension.

[F5 Dave]

" as the rear end rise's it pushes the rear into the track whichs keeps the front on the ground for better turning".

Thats dead correct except its back to front thinking in my opinion.
If you have an issue with running wide on exit then you need to look at gaining some front end turn - drop the forks thru.
Gaining front grip by killing the rear end with anti squat does "work " but in the example I gave with the Frepin, it was loosing rear grip under power when tipped over hard.
So I didnt try to fix that by reducing the front grip, I dialled in some more natural rear grip by reducing the anti squat % - dropping the rear ride height.
This works just as well around the sweeper at Mt Welly where even at those slow speeds the suspension is heavily compressed.
No Mates bike initially used to step the back out when leaned over going as hard as he could around the sweeper.
Dropping the back gained some rear grip by reducing the anti squat.
It then started to run wide on turn in,so rather than reduce the good rear grip we had just gained he dropped the forks thu to steepen up the front.
Now it steered, and had rear edge grip - seemed to work OK, he won on Mt Welly 3 years in a row.

Same idea with Discombs TZ350 around Hampton when he won the Sheene last year.
It was pattering and loosing front grip when hard over exiting the sweeper under power - that bike has near on no anti squat at all, so all we could do was reduce the squat by winding in
a heap of preload and a couple of compression clicks.
This stopped the rear from squatting so much and unloading the front - then it steered at full noise onto the front straight - seemed to work, he was 3 secs a lap faster than anyone in his class.

Its always best to try and gain grip to balance out a lack at one end, reducing the grip at the opposite end can and does work - if that all that can be done to fix pig handling.

niges real problem is the spring at the rear is too soft for his fat arse. I spent a bunch of time watching at the last GP as my bike had welded it's clutch. And you could see it going full stroke and stepping dread fully at Tokaroa which is a severe track. He hadn't noticed but was still frothing at the mouth post race. Ahh we're all getting too old. To be fast again.

[TZ350]

I actually thought it was an interesting thing to discuss.

Me too, as its a topic I am going to have to learn more about.

So as I understand it so far (and probably incorrectly):-

If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front. Un loading the front under power can allow the bike to run wide.

Ant squat or the back rising up transfers weight to the front wheel for front end grip when turning in and with less weight on the back, the back could tend to slide out.

Because its been our habit to tie the bikes down so tight on the dyno I have not really observed if ours squat or otherwise, interesting that we can use a run on the dyno to observe changes made to this part of the suspension setup.

[wobbly]

What many forget is that there is a finite mass of bike and rider.
Using antisquat to transfer some of that finite amount to the front - MUST by definition reduce the rear.
Less or neutral anti squat by dropping the ride height and the swingarm angle ,allows more weight transfer to the rear - increasing grip at that end.
The anti squat rising force is an internal frame vector, the actual result of the frame rising ( thus the rear wheel pushing down ) is weight transfer off
the rear and onto the front - counter intuitive I know, but increased FRONT grip is what actually happens in the end.
Add to that the dramatic increase in effective rear bump rate under power, and anti squat although intellectually an obviously useful tool, suddenly becomes a very sharp double edged sword.

[wobbly]

One thing to be careful of TeeZee is that the rear wheel will try to climb up the dyno roller under power - giving the illusion of a big anti squat %.
To get an idea of the squat rate you have to be aware of the wheel position.

[TZ350]

One thing to be careful of TeeZee is that the rear wheel will try to climb up the dyno roller under power - giving the illusion of a big anti squat %. To get an idea of the squat rate you have to be aware of the wheel position.

Thanks for the tip.



I can see the possibility of a headache coming on, while trying to get to grips with understanding suspension tuning.

[Drew]

Get the spring rate right, set he sag with rider, and static the swingarm should be pointing close to the middle of the front sprocket or slightly above.

Adjust the tendency to run wide or tip too fast with fork height. This is the start point. From it you are in the crazy land of suspension damping, and the endless trade offs you are forced to deal with.

You're pissing in the wind with the wrong springs.

Have fun.

[mr bucketracer]

Me too, as its a topic I am going to have to learn more about.

So as I understand it so far:-

If the back squats down under power it puts more weight and therefor traction on the back wheel and un loads the front. Un loading the front under power can allow the bike to run wide.

Ant squat or the back rising up transfers weight to the front wheel for front end grip when turning in and with less weight on the back, the back could tend to slide out.

Because its been our habit to tie the bikes down so tight on the dyno I have not really observed if ours squat or otherwise, interesting that we can use a run on the dyno to observe changes made to this part of the suspension setup.

squat with ant squat working together is what gives traction , remove ant squat out of it and let it squat under power will i think go from unloaded to overload as it bottoms out , i bit of both is a good controlable ride

[Moooools]

What many forget is that there is a finite mass of bike and rider.
Using antisquat to transfer some of that finite amount to the front - MUST by definition reduce the rear.
Less or neutral anti squat by dropping the ride height and the swingarm angle ,allows more weight transfer to the rear - increasing grip at that end.
The anti squat rising force is an internal frame vector, the actual result of the frame rising ( thus the rear wheel pushing down ) is weight transfer off
the rear and onto the front - counter intuitive I know, but increased FRONT grip is what actually happens in the end.
Add to that the dramatic increase in effective rear bump rate under power, and anti squat although intellectually an obviously useful tool, suddenly becomes a very sharp double edged sword.

Could you explain where this increased grip on the front wheel is coming from?

Anti squat causes an increase i frame height (or in reality pitches the bike forward) when accelerating. Under steady acceleration the only affect this will have is to raise the COG height of the bike+rider, which will increase normal load on the rear wheel (due to pitching moment from acceleration), and take it off the front - more rear grip, less front.

Under a transient acceleration (acceleration of acceleration) the chassis will be accelerated upwards, and a reaction force will be seen at the rear wheel (D'Alembert's principle). This reaction force stops when the acceleration becomes steady or begins decreasing. This is more often a smoother affair and is unlikely to happen during a corner. So - More rear grip followed by maybe less rear grip if you decide to shut the throttle.

I am struggling to see in all this a reason for the front wheel to see increased grip. What am I missing?

EDIT: Is it inertial moments causing the bike to pitch about some point ahead of the COG, causing a larger reaction force at front wheel due to a shorter moment arm? That would mean that the motion increases load on both wheels (but more so at the front) and the reverse motion (springing back to neutral position) unloads both wheels. (Not sure I explained that too well)

[Drew]

squat with ant squat working together is what gives traction , remove ant squat out of it and let it squat under power will i think go from unloaded to overload as it bottoms out , i bit of both is a good controlable ride

The spring is constantly pushing the wheel onto the road. Corectly sprung you should be able to tune with damping for nearly any track.

Antisquat is getting to the uppermost technical side of suspension tuning. 99% of riders need never worry about it unless they get a bike that's been set up too high to begin with.

[Drew]

Could you explain where this increased grip on the front wheel is coming from?

Anti squat causes an increase i frame height (or in reality pitches the bike forward) when accelerating. Under steady acceleration the only affect this will have is to raise the COG height of the bike+rider, which will increase normal load on the rear wheel (due to pitching moment from acceleration), and take it off the front - more rear grip, less front.

Under a transient acceleration (acceleration of acceleration) the chassis will be accelerated upwards, and a reaction force will be seen at the rear wheel (D'Alembert's principle). This reaction force stops when the acceleration becomes steady or begins decreasing. This is more often a smoother affair and is unlikely to happen during a corner. So - More rear grip followed by maybe less rear grip if you decide to shut the throttle.

I am struggling to see in all this a reason for the front wheel to see increased grip. What am I missing?

This is getting fucking stupid.

With the rear shock unable to compress, as soon as the tyre reaches the top of a bump YOU LOSE TRACTION. Not gain it.

Ps. Weight distribution is where tye extra front grip comes from. But it is important to realise that this is a different part of the turn. Corner entry is where raising the rear gives more front grip, the trade off being less exit grip at the rear.

[Moooools]

This is getting fucking stupid.

With the rear shock unable to compress, as soon as the tyre reaches the top of a bump YOU LOSE TRACTION. Not gain it.

Ps. Weight distribution is where tye extra front grip comes from. But it is important to realise that this is a different part of the turn. Corner entry is where raising the rear gives more front grip, the trade off being less exit grip at the rear.

Anti squat doesn't remove the ability for the rear shock to compress though , unless you were to run a shit tonne of it and topped the shock out. The spring can still compress just the same, it is just sitting higher than it was.
Bumps aren't the only transient concern on a motorcycle. In fact they are a pretty small factor compared to inertial loads when you are riding around on billiard tables i.e. a racetrack.

[wobbly]

Wrong - anti squat force is obtained by the chain trying to pull the rear wheel forward, or put another way - to shorten the swingarm.
When the swingarm is at an acute downward angle, as the chain pulls harder the resultant anti squat reaction forces the rear of the bike upward.
By the obvious physics of action and equal re action, then rear wheel is being pushed downward at the same time with the same force value.
Thus it is this reaction force ( an internal frame force ) that prevents a bump or track ripple from compressing the rear shock, via the rear wheel rising
in relation to the seat height.
So although the shock/spring combination may actually physically able to compress, it cant due to the high internal frame force trying to lengthen the shock.
When in this powered on state, a bump will have to lift the rear of the bike AND the riders bum mass as well, this is not called suspension, its called a jolt in the arse
closely followed by an instantaneous slide, closely followed probably by a highside - they hurt.
To prove any theory, go to the nth degree.
With a lot of pro squat dialled in via front sprocket height, and or swingarm angle - under power on conditions ultimately ALL the bike/rider mass will be transferred to the rear tyre.
ie a wheelstand.
Watch MotoGP today and on virtually every corner exit the front tyre is just off the deck, thus they have just enough weight transfer ( and auto Hp control ) to give the absolute
maximum rear grip available - the front tyre is off the ground, directional control is then only via counter-steering and rider weight.

[TZ350]

Squat Anti Squat




The calculations for anyone game enough to risk brain damage.

http://supermotojunkie.com/showthrea...tric-supermoto

Remember that guy who was building an electric bike in Wellington.

Well I came across this one, 137kg with rider and by the looks of it an electric bike could be very competitive on a Kart track.

Electric bike kicks arse:- https://www.youtube.com/watch?v=xC9KYF-SJkU

Electric bike dyno run:- https://www.youtube.com/watch?v=bwoGXQDzB-s

[el chupacabra]

Is there any chance anyone here could give more info about the swissauto 500? I am curious to know if the cylinders fired in pairs etc. Any pictures would be sweet.

I have read through most of this and this particular engine interests me very much so, I cant understand why it wasn't done more, the flying web crank.