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Setup extras: Fork Offset and Swing Arm Length

Started by Asdrael, March 19, 2017, 01:52:01 PM

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Asdrael

March 19, 2017, 01:52:01 PM Last Edit: March 19, 2017, 09:22:39 PM by Asdrael
So we have a good suspension setup guide from Stonerider found here: http://forum.mx-bikes.com/index.php?topic=1463.0

... but why is noone talking about ForkOffset and Swing Arm Length?

Those two settings have, in my experience with OEM bikes, the most influence on the actual front and rear end behaviour of the bike - their combination resuting in drastic changing in feel and balance.

Those settings can be found in the Garage / Others tab / Geometry section.

Fork offset.

It's the distance between the fork and the steering axis. Most bikes have a default value between 22 and 25mm stock. Your offset value adds/removes from that. A 2mm change is already pretty big - 10%.

Decreasing this distance by putting a negative OffSet value generally:
  • Shifts the bike weight to the front, increasing front grip, decreasing rear grip.
  • Increases bike handling, giving a feeling of more controlled and sharper turning
If you find your chosen bike a big slugish with a fuzzy front end, go with -2 and that'll do wonders. Conversly, if you feel the rear end goes everywhere and only the front is reliable, +1 or 2 will change that.


Swing Arm Length.

This is the distance between the Swing Arm pivot point and the rear axle. A standard swingarm is around 590mm. The range of change is around 30mm. There are three positions: middle (1), short (0) and long (2).

A longer swingarm:
  • Shifts bike weight to the front
  • Tends to lessen any excessive wheelie issue
  • Increases turn radius
  • Gives a bit of a sluggish feeling when turning
  • Makes the rear less twitchy when powersliding - the rear wheel will not move as much
  • Makes the rear more mobile twitchy when it starts moving while breaking hard from the front
If you find you are losing the rear uncontrollably, try to go with a longer swingarm. Conversly, if you feel the bike is very rear heavy, a setting of 0 will help. Do not forget that changing the SwingArm Length changes how the rear shock is linked to the wheel! You will need to adjust your preload!

Setting interaction.

As you can see, the impact of some SwingArm settings overlap with the Fork Offset settings. But not all. So you can really impact the behaviour of the bike this way, and a chassis you don't gel with but love the engine off can be quite extensively modified to suit your style better.

Generally, a change of 1 step in swingarm length changes the weight distribution as much as 2 steps in fork offset.

As a rule of thumb, this is valid only when your suspension are properly tuned. A change in offset / length will never stop a fork from bottoming out, or a shock from being too hard and making you lose grip because it skims over terrain. Set you sag, get a good ballpark of Bump/Rebound values. THEN change fork offset and swingarm length. You will maybe fine tune the suspension again afterwards, but you'll be at least working in the right direction.


Hope that helps!
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StoneRider

thanks man :) thanks a lot ! we need you to redo all my tutorial !! xD

HornetMaX

I thought a longer swingarm gives a bigger turn radius. Typo or am I wrong ?

Asdrael

Quote from: HornetMaX on March 19, 2017, 08:52:32 PM
I thought a longer swingarm gives a bigger turn radius. Typo or am I wrong ?

You are correct, I did a typo - I was thinking that it lowers the performance in terms of turn radius and typed it too fast.

Longer swingarm - bigger radius.
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CBM Racing

Quote from: Asdrael on March 19, 2017, 01:52:01 PMSo we have a good suspension setup guide from Stonerider found here: http://forum.mx-bikes.com/index.php?topic=1463.0

... but why is noone talking about ForkOffset and Swing Arm Length?

Those two settings have, in my experience with OEM bikes, the most influence on the actual front and rear end behaviour of the bike - their combination resuting in drastic changing in feel and balance.

Those settings can be found in the Garage / Others tab / Geometry section.

Fork offset.

It's the distance between the fork and the steering axis. Most bikes have a default value between 22 and 25mm stock. Your offset value adds/removes from that. A 2mm change is already pretty big - 10%.

Decreasing this distance by putting a negative OffSet value generally:
  • Shifts the bike weight to the front, increasing front grip, decreasing rear grip.
  • Increases bike handling, giving a feeling of more controlled and sharper turning

If you find your chosen bike a big slugish with a fuzzy front end, go with -2 and that'll do wonders. Conversly, if you feel the rear end goes everywhere and only the front is reliable, +1 or 2 will change that.


Swing Arm Length.

This is the distance between the Swing Arm pivot point and the rear axle. A standard swingarm is around 590mm. The range of change is around 30mm. There are three positions: middle (1), short (0) and long (2).

A longer swingarm:
  • Shifts bike weight to the front
  • Tends to lessen any excessive wheelie issue
  • Increases turn radius
  • Gives a bit of a sluggish feeling when turning
  • Makes the rear less twitchy when powersliding - the rear wheel will not move as much
  • Makes the rear more mobile twitchy when it starts moving while breaking hard from the front

If you find you are losing the rear uncontrollably, try to go with a longer swingarm. Conversly, if you feel the bike is very rear heavy, a setting of 0 will help. Do not forget that changing the SwingArm Length changes how the rear shock is linked to the wheel! You will need to adjust your preload!

Setting interaction.

As you can see, the impact of some SwingArm settings overlap with the Fork Offset settings. But not all. So you can really impact the behaviour of the bike this way, and a chassis you don't gel with but love the engine off can be quite extensively modified to suit your style better.

Generally, a change of 1 step in swingarm length changes the weight distribution as much as 2 steps in fork offset.

As a rule of thumb, this is valid only when your suspension are properly tuned. A change in offset / length will never stop a fork from bottoming out, or a shock from being too hard and making you lose grip because it skims over terrain. Set you sag, get a good ballpark of Bump/Rebound values. THEN change fork offset and swingarm length. You will maybe fine tune the suspension again afterwards, but you'll be at least working in the right direction.


Hope that helps!

I am sorry I don't understand. When we have an issue with our riders having issues with tight turns we remove the stock Tripple Clamps and replace them with a set of 22mm offset ones. So how does this work in the game? I have never seen a set of Tripple Clamps that push the suspension and tire away from the bike so what does each setting do. If it has a -next to it does that mean it is bringing the wheel closer to the frame? I really wish this game came with an instruction manual mapping out exactly what each setting does. If you are interested I will write it if you know what every setting does including front dag which does not exist in real life. I would be happy to help I already know a lot including what every input one setting can do especially for the brakes. I always love your work and would be happy to work with you!
Cheers

Asdrael

I beleive the offset setting is a deviation from the stock value (that is set in the bike editor). "-2" reduces the offset by 2mm. It used to make sense in the 90's and 2000's when stock offsets were 25mm. Nowadays, stock offsets are 22mm (I think only Kawi has a 23mm one) so people don't really change it anymore. As for going for high end triple clamps, I suspect it has more to do with rigidity and feel than anything else if the offset doesn't change.

And thanks for hte offer on the setup, I ll be sure to take it up once I get stuck again modding ;) Currently, the only hard value that can be measured is the weight height bias but it is a bitch to do, so I went with Honda schematic that put it around 45% with suspensions extended.
Donate to me -> feed my coffee addiction -> get more mods!
OEM bikes pack
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CBM Racing

Quote from: Asdrael on March 19, 2017, 01:52:01 PMSo we have a good suspension setup guide from Stonerider found here: http://forum.mx-bikes.com/index.php?topic=1463.0

... but why is noone talking about ForkOffset and Swing Arm Length?

Those two settings have, in my experience with OEM bikes, the most influence on the actual front and rear end behaviour of the bike - their combination resuting in drastic changing in feel and balance.

Those settings can be found in the Garage / Others tab / Geometry section.

Fork offset.

It's the distance between the fork and the steering axis. Most bikes have a default value between 22 and 25mm stock. Your offset value adds/removes from that. A 2mm change is already pretty big - 10%.

Decreasing this distance by putting a negative OffSet value generally:
  • Shifts the bike weight to the front, increasing front grip, decreasing rear grip.
  • Increases bike handling, giving a feeling of more controlled and sharper turning
If you find your chosen bike a big slugish with a fuzzy front end, go with -2 and that'll do wonders. Conversly, if you feel the rear end goes everywhere and only the front is reliable, +1 or 2 will change that.


Swing Arm Length.

This is the distance between the Swing Arm pivot point and the rear axle. A standard swingarm is around 590mm. The range of change is around 30mm. There are three positions: middle (1), short (0) and long (2).

A longer swingarm:
  • Shifts bike weight to the front
  • Tends to lessen any excessive wheelie issue
  • Increases turn radius
  • Gives a bit of a sluggish feeling when turning
  • Makes the rear less twitchy when powersliding - the rear wheel will not move as much
  • Makes the rear more mobile twitchy when it starts moving while breaking hard from the front
If you find you are losing the rear uncontrollably, try to go with a longer swingarm. Conversly, if you feel the bike is very rear heavy, a setting of 0 will help. Do not forget that changing the SwingArm Length changes how the rear shock is linked to the wheel! You will need to adjust your preload!

Setting interaction.

As you can see, the impact of some SwingArm settings overlap with the Fork Offset settings. But not all. So you can really impact the behaviour of the bike this way, and a chassis you don't gel with but love the engine off can be quite extensively modified to suit your style better.

Generally, a change of 1 step in swingarm length changes the weight distribution as much as 2 steps in fork offset.

As a rule of thumb, this is valid only when your suspension are properly tuned. A change in offset / length will never stop a fork from bottoming out, or a shock from being too hard and making you lose grip because it skims over terrain. Set you sag, get a good ballpark of Bump/Rebound values. THEN change fork offset and swingarm length. You will maybe fine tune the suspension again afterwards, but you'll be at least working in the right direction.


Hope that helps!

Honestly, I spoke to my friend who was a YOT and Factory Honda Mechanic for Fonseca and he had no clue why the game would offset the forks in two different ways. Normally if you are having a hard time with tight corners you get a set of 22mm offset Triple Clamps and they work wonders but which way brings the Wheel closer to the Frame to help wit the stability of tight turning. We were guessing when it said - but he and I have ever heard of extending them forwards beyond stock that just isn't something that would work on a factory Race Bike it would make the bike handle worse like riding a chopper obviously on a smaller scale. Unless we are misunderstanding how PiBoSo has it all setup? I don't understand a lot of the settings in this game. I wish I could pick PiBoSo's brain and write up a full instruction manual of exactly what every setting is there for and how it changes the bike for all the people that are new. I know what the swingarm adjustment does that is one of the first things I do when I buy a new bike I push the wheel as far in as possible and then remove a few links from the chain so the bike is more nimble. Thanks for trying to explain it and bringing it to people's attention. As soon as I set my Sag ( another thing what's up with front Sag?) I always set my swing arm to 0 and I adjust the clamps to what I think is bringing the wheel closer in. In Beta 13 it worked wonders I immediately dropped my lap time by 2-3 seconds because I could charge into the inside lines and charge out of them. Now I am still losing the front because of how stiff he made the suspension no matter how soft I try to make it. But at least it is not bouncing anymore and tosing you over the bars. If you are interested I would love to make a Beta 14 settings guide at some point that will explain everything to the rush of people that bought the game once it was released on Steam. Most people I talk to tell me hey only change their view. They never mess with any of the settings.
Cheers