Do the "Bump" and "Rebound" settings actually work on GP Bikes?
I tested them at the extremes of the settings and hardly felt any difference in the handling of the bike at all. Test bike was on the Verase 500cc bike.
Now surely these settings, in co-operation with the other suspension settings, that are supposed to help keep the tyres on the track surface at all times over, undulations, bumps, acceleration and braking phases, these settings should be vital to be set correctly otherwise you would surely risk some scary moments on track?
Hey..... Have I actually found a subject that has foxed you physics guys?? Hehe
C'mon someone must know something about the workings of the bump and rebound settings to comment on whether they seem to work in GP Bikes or not?
Any takers? Max?.... C21?... Neoraptor?..... anyone?
Hehe, suspensions setup is more an art than a science, because it involves an awful lot of feedback from the rider to the engineers and we all know that talking to an engineer is not easy :) (assuming the rider can express what he wants, and this too is not given).
Anyway, GPB settings do work and you can feel the difference, even on a very smooth track.
The basics, just to be sure we're all aligned.Bump and rebound are damping settings, in fact they are nothing more than frictions within the damper (obtained pushing oil through small holes, oversimplifying). That's totally different compared to the spring setting, which is a stiffness.
A stiffness tells you how much the spring (hence the fork) will compress under a given force. E.g. a 20 N/mm spring will compress by 1mm when under 20N, 2mm under 40N and so on.
A damping tells you how fast the damper (hence the fork) will compress. E.g. 20N/mm spring + damper under 20N will always end up compressed by 1mm, no matter the value of the damping. However, if damping is low, you'll reach the 1mm compression quickly while if it's high you'll ned more time to reach 1mm.
So small bump value ==> the fork will compress quickly, high bump value ==> the fork will compress slowly. Same for rebound, replacing "compress" with "extend".
Example a fork with high bump but low rebound will compress slowly (passing over a bump or under front braking, for example) but will extend quickly (passing over a pothole or when opening the throttle).
On many modern bikes you not only have separate settings for bump (compression) and rebound (extension), but you also have separate settings for low/high suspension speeds (technically, low/high flow rates). So you have 4 settings: bump low/high speed, rebound low/high speed. For example you can have a low damping for bump at low speeds (speed here is not bike's speed, it's the fork's speed) but a high damping at high speeds.
In motogp (and probaly sbk too) it's even more complex than that, so complex in fact that there are so many settings that a software tells you what to change and how, depending on what you want to achieve.
From here on, you're on your own :)
MaX.
Test it on the 125cc ;D
To be honest i did not played /changed the settings yet that much...
Spring adjustment is definetly working , you can check that in the replay.....ahh.....asking for bump and rebound....
QuoteExample a fork with high bump but low rebound will compress slowly (passing over a bump or under front braking, for example) but will extend quickly (passing over a pothole or when opening the throttle).
in the worst scenario: at constant speed the fork will stuck deeper and deeper because of the low rebound if you´re driving upon a rough surface...imho ???
Hi Max.
This is very interesting information! ;D
So on a ruff/bumpy track, if I set the springs pretty stiff, the bump high(to absord the bumps better), and the rebound high(to extend fast after hitting bumps), I should have better grip and handling? Do I have this correct?
Edit: Or is it with low rebound for this setting?
Quote from: C21 on February 07, 2014, 03:46:12 PM
in the worst scenario: at constant speed the fork will stuck deeper and deeper because of the low rebound if you´re driving upon a rough surface...imho ???
YES! that is sth you have to be aware of ... not many think of that
Quote from: Hawk_UK on February 07, 2014, 06:16:41 PM
So on a ruff/bumpy track, if I set the springs pretty stiff, the bump high(to absord the bumps better), and the rebound high(to extend fast after hitting bumps), I should have better grip and handling? Do I have this correct?
Hmm, no :)
High bump ==> the damper will respond (i.e. compress) more slowly to a quick road bump than with low bump: the height variation will hence be "transmitted" more to the chassis (than in the case with a low bump setting).
In general a softer spring and a low bump and rebound will allow your wheel to "follow" the track bumps better. The ride is more comfortable (that's important for road bikes).
The problem of course is that if the setup is too soft, the fork may bottom out (reach its maximum), especially under hard braking (which is bad, leading to poor braking performance).
For the rear, it is more or less the same, minus the braking constraint. As a general rule, a softer (low bump/rebound) rear will give you better traction.
Globally however, a harder bike will be more precise while a softer one will be less.
Overall, it's a big trade-off: precision (better if hard), road following (better if soft), avoiding bottoming out (better if hard) etc.
Spring stiffness will also alter the riding height (and the natural pitch of the bike).
Bump/rebound settings also alters the bike behavior entering/exiting a corner (over/understeer, even if using understeer to describe the bike widening the trajectory when opening the throttle out of a corner is a bit of an abuse).
MaX.
Quote from: Hawk_UK on February 07, 2014, 06:16:41 PM
if I set the springs pretty stiff, the bump high(to absord the bumps better)
this is incorrect - in general low bump damping and rather soft springs should absorb surface irregularities better - but it should
NOT be too soft, otherwise the effect is reversed as the spring will just hit bottom and therefore have no absorbing capability left... so why don't riders not run with soft settings all the way? --> because rather soft suspension, esp. in the fork, makes the turning feel slow and irresponsive - and that is sth you want to avoid when running a race bike ;) so riders in general seek a rather hard suspension setting but have to find a compromise on rough surface....
PS: the master was faster :P
Quote from: Stout Johnson on February 07, 2014, 06:37:07 PM
PS: the master was faster :P
Just because the springs below my (mechanical) keyboard keys are stiffer than yours :)
MaX.
@Max/Stout: Hehe.... I'm determined to get my head around this, so in layman's terms:
- Rebound: Low value setting = Faster extenstion of the suspension after hitting a bump
High value Setting = Slower extention of the suspension after hitting a bump
- Bump: Low value setting = Faster compression of the suspension after hitting a bump
High value setting = Slower compression of the suspension after hitting a bump
Thanks for bearing with me guys. Hehe ;) ;D
Quote from: HornetMaX on February 07, 2014, 06:44:05 PM
Quote from: Stout Johnson on February 07, 2014, 06:37:07 PM
PS: the master was faster :P
Just because the springs below my (mechanical) keyboard keys are stiffer than yours :)
MaX.
@ MaX: LOL! ;D
@Hawk: yes ;)
Quote from: Stout Johnson on February 07, 2014, 06:55:17 PM
Quote from: HornetMaX on February 07, 2014, 06:44:05 PM
Quote from: Stout Johnson on February 07, 2014, 06:37:07 PM
PS: the master was faster :P
Just because the springs below my (mechanical) keyboard keys are stiffer than yours :)
MaX.
@ MaX: LOL! ;D
@Hawk: yes ;)
Hooray!! ;D
Thanks guys, I can get my head around it thinking of it in that way.
Now I'll go put my head on ice. Hehe
Quote from: Hawk_UK on February 07, 2014, 06:48:24 PM
- Rebound: Low value setting = Faster extenstion of the suspension after hitting a bump
High value Setting = Slower extention of the suspension after hitting a bump
- Bump: Low value setting = Faster compression of the suspension after hitting a bump
High value setting = Slower compression of the suspension after hitting a bump
Nicely put Hawk_UK, I may even re-use your wording somewhere !
MaX.
Thanks, Max. Please do. ;)
MaX, I think we should have these threads "featured" somewhere - they might be of interest to many - especially maybe guys new to motorcycle sims. Maybe you could feature these kind of threads under section "Setups"? (or some kind of "physics discussions")
Guess that under "setups" it may make sense.
Yaaawn ... another thing on my todo list ;)
MaX.
Quote from: HornetMaX on February 07, 2014, 10:11:35 PM
Guess that under "setups" it may make sense.
Yaaawn ... another thing on my todo list ;)
MaX.
hehe sorry! ;)
(easy way out: you could just delete my proposal post and ban me from the forum)
Quote from: Stout Johnson on February 08, 2014, 12:16:10 AM
(easy way out: you could just delete my proposal post and ban me from the forum)
I'm no longer moderator so that's not an option. Not that I would have done it anyway (at least in your case) :)
MaX.
Quote from: HornetMaX on February 08, 2014, 11:17:58 AM
Quote from: Stout Johnson on February 08, 2014, 12:16:10 AM
(easy way out: you could just delete my proposal post and ban me from the forum)
I'm no longer moderator so that's not an option. Not that I would have done it anyway (at least in your case) :)
MaX.
OH Noooo! You were the best moderator we've ever had, Max! That is very sad news! :( :(
Why did you give it up? You were doing a BRILLIANT job, mate! I'm very surprised and shocked at this news. A sad day for the community. :( :(
Quote from: Hawk_UK on February 08, 2014, 11:31:41 AM
OH Noooo! You were the best moderator we've ever had, Max! That is very sad news! :( :(
Why did you give it up? You were doing a BRILLIANT job, mate! I'm very surprised and shocked at this news. A sad day for the community. :( :(
I had a minor fight with Piboso about some stupid comments I posted on other forums (you can read a summary here: http://forum.piboso.com/index.php?topic=401.msg6555#msg6555 (http://forum.piboso.com/index.php?topic=401.msg6555#msg6555), a prior part of the discussion was in italian between me and him and has been removed from the thread).
Whole thing is my fault as, despite the fact it was trash-talking more than anything else, that comments I posted were indeed offensive if taken literally.
Anyway, the issue is sorted out (as you can see in the subsequent messages) and I'm happy we agreed to that.
I'm not sure I'm good for the moderator role (and I surely understand the decision of removing me from it after what happened) so that's not a problem at all.
But don't worry, I'll continue to help around here whenever I can and others will take up on the moderator role (if needed, RiccoChicco is already on it).
MaX.
Well having just read the thread mentioned. I can only say that I personally admire people who have the guts to speak there mind, although on occasions it is wise to stand back and say little to avoid saying something in the heat of the moment that is a bit too much said, and something that you will somewhat regret having said later. ;) But it's good that you both didn't completely fall out over the issue and managed to resolved your differences with each other in the end. :)
It's all a big shame though. You have been so instrumental in getting great information(Particularly with regards to modding), with the help of others too, organised and listed in easy to find threads, not to mention your obvious great knowledge about physics, etc, etc, that greatly help us all to better understand the workings of a racing bike and why it does what it does at times. I only hope Ricco will continue to update and maintain those important threads the same as you did? Just seems a big job for just one person.
Oh well, what's done is done.... at least you said you will still be around to help us all, which is great! ;D
I for one will continue to pick your brains from time to time. Hehe
You've done a BRILLIANT job, mate. Don't forget it! ;) 8)
Quote from: Hawk_UK on February 08, 2014, 02:54:34 PM
I only hope Ricco will continue to update and maintain those important threads the same as you did?
I'll do my best. :)
Quote from: Hawk_UK on February 08, 2014, 02:54:34 PM
Just seems a big job for just one person.
It is. Maybe PiBoSo will ask for a second moderator (i don't know).
Quote from: RiccoChicco on February 08, 2014, 06:15:53 PM
Quote from: Hawk_UK on February 08, 2014, 02:54:34 PM
I only hope Ricco will continue to update and maintain those important threads the same as you did?
I'll do my best. :)
Quote from: Hawk_UK on February 08, 2014, 02:54:34 PM
Just seems a big job for just one person.
It is. Maybe PiBoSo will ask for a second moderator (i don't know).
Thanks Ricco. I didn't mean any disrespect in my words at all. I know you do a good job too, you've always been there when I've needed to get something done. I just hope Piboso will take on another moderator to ease the work load and help you keep things organised. Being a moderator is a lot more work than some people realise. ;) :)