Sideslip angle, wut ?

[HornetMaX]

Hi max, for me Stout has done a great job of doing that already mate. In the video and the stills it shows the nose of the bike pointing to the outside of the track but it's coming towards you.

I guess you refer to the image under "Situation 1" (of the 4 Stout has posted above).
What I see there is totally possible. The bike is leaning: this means than on top of the thrust (that is in the "bike's" direction) you also have a lateral force on the rear tire (even if the rear tire is not sliding at all): it's the Camber thrust. It pushes the rear wheel (and hence the bike) towards the interior of the turn. Because of that, the bike may not go towards the direction it is pointing to (most likely, thanks also to the light front).

And your right about Lukey Heights at Victoria Stout. As you come over the crest of the left and into the tight right hand hairpin it's all over the place.

Lukey heights is on a slope (and a little banked too IIRC), we already know there are issues with this kind of corners.

MaX.

[Forty6]

It's probably more the 1st image of situation 2. The bike has completed the turn and is now starting to straighten up. But the nose is still looking as though it's heading off track and the bike is coming towards you. I get what your saying regarding a lightening front end under power but the nose/front should now be going in the direction of the rear tyre. And if it was down to the rear sliding then the nose would be pointing to the inside of the turn as shown in the second image of situation 2. It's like, I get what Stout is saying and totally agree. But explaining it is a totally different matter. I suppose if you don't see it, then you don't see it. 

[HornetMaX]

It's probably more the 1st image of situation 2. The bike has completed the turn and is now starting to straighten up. But the nose is still looking as though it's heading off track and the bike is coming towards you. I get what your saying regarding a lightening front end under power but the nose/front should now be going in the direction of the rear tyre. And if it was down to the rear sliding then the nose would be pointing to the inside of the turn as shown in the second image of situation 2. It's like, I get what Stout is saying and totally agree. But explaining it is a totally different matter.

I think we're pretty clear (now) on what's bothering. Roughly speaking, at turn's end (e.g. from 0:12s) the bike is pointing at me (or slightly to the right of the screen) while it is globally moving left. To me it's not an issue and I also think the specific perspective is playing a role here: the fov and the fact the camera is straight in front makes you notice more any side movement than any forward movement, giving the impression the bike is "floating to the left of the screen".

That's why having the replay is good in such cases, you can have a look from different angles.

I suppose if you don't see it, then you don't see it. 

I do see it, I just think it's not an issue. Not the same thing

MaX.

[Forty6]

Glad you see it  but I don't necessarily feel it's the camera angle on the replay that exaggerates the movement as it's really clear from 3rd person camera which isn't static but it's following the bike/rider. It for me also happens mid corner or on corner entry. It looks like your loosing the front but your not. Where's Stout when you need him? He's much better at explaining 

[HornetMaX]

Glad you see it  but I don't necessarily feel it's the camera angle on the replay that exaggerates the movement as it's really clear from 3rd person camera which isn't static but it's following the bike/rider. It for me also happens mid corner or on corner entry. It looks like your loosing the front but your not.

I'd think something like a helicopter view (fixed camera even, if possible in terms of zoom) should be the best to detect this kind of trajectory-related issues.

Where's Stout when you need him? He's much better at explaining 

He's probably "supervising his french maid" 

MaX.

[janaucarre]

Thanks to BOBR6 84.
From weeks i search to reproduce what you posted.
I think it's a strange things, the rear wheel really doesn't follow the front wheel. I'm ok it happens in real, but i think it looks to much strange in gpbikes, like the effect is to big than in reality.

[BOBR6 84]

Right! 
Im not trying to nitpick at gpbikes its just it doesnt look right at all to me.. As we all know its more noticable on up/downhill turns but its always there.. Almost like the front tyre isnt connected to the track?

I fully accept what maX is saying but like janau said its seems a bit over the top compared to reality.

So track surface problem?
Tyre slip problem?
Or other?
Thats all beyond me.. All I can do is point out what I see..

[Stout Johnson]

Where's Stout when you need him? He's much better at explaining 

He's probably "supervising his french maid" 

MaX.

LOL! I am very busy, because had to do all the stuff a housemaid is supposed to be doing... She is not good at that, but she is VERY good at the stuff a wife is supposed to be doing

I guess you refer to the image under "Situation 1" (of the 4 Stout has posted above).
What I see there is totally possible. The bike is leaning: this means than on top of the thrust (that is in the "bike's" direction) you also have a lateral force on the rear tire (even if the rear tire is not sliding at all): it's the Camber thrust. It pushes the rear wheel (and hence the bike) towards the interior of the turn. Because of that, the bike may not go towards the direction it is pointing to (most likely, thanks also to the light front).

Well that's a good point. But camber thrust does only account for the wheels running towards the interior of the turn, it does not account for the bike pointing towards the outside while running towards the inside.  Also, the camber thrust is getting less and less towards the end of the video (as the lean angle is getting less), but the wrong direction issues is more and more obvious...

To me it's not an issue and I also think the specific perspective is playing a role here: the fov and the fact the camera is straight in front makes you notice more any side movement than any forward movement, giving the impression the bike is "floating to the left of the screen".

That's why having the replay is good in such cases, you can have a look from different angles.

Well, the angle you look at it, does play a big role ofc. If it was so obvious that it didn't, I assume we would not have this discussion here as it was clear to all that there was a problem (if there is any). It is natural that I tried to use an angle that made it as obvious as possible in order to show it clearly. But I can assure you that it can be observed from many angles, I did not arrange a rare optical illusion. For me (and luckily others too) it is even noticeably in standard cameras, on certain tracks and certain turns (e.g. Lucky Heights). I do have some replays saved, but I doubt that you will come waving at me that you now all of a suddon see the problem, when you do not see it with me trying to make it as obvious as possible.

It is like forty6 said:

Glad you see it  but I don't necessarily feel it's the camera angle on the replay that exaggerates the movement as it's really clear from 3rd person camera which isn't static but it's following the bike/rider. It for me also happens mid corner or on corner entry. It looks like your loosing the front but your not.

It really does look like your loosing the front, like when braking too hard into a turn and you lose the front. But this issue we try to report here in GPB happens while accelerating mid-turn, more noticeable with more lean angle.

I'd think something like a helicopter view (fixed camera even, if possible in terms of zoom) should be the best to detect this kind of trajectory-related issues.

I tried that today... BUT with not really satisfactory result. When using non-static camera, you just do not see any issue at all. When using static camera, you have to zoom out very far. Good thing is you can see the trajectory of the bike. Bad thing is, you can hardly differentiate between front and rear wheel trajectory. So, I might have seen a clue of the problem, but is much much more noticeable in the video I posted ealier. If you dont see it there, you will not see it from bird view. My conclusion is, that the overall trajectory of the bike seems fine (as far as I could say from zoomed out view). So I think it is really only an issue of the orientation of the bike (bike pointing to the outside while running towards the inside of the turn) which is less noticeable from zoomed out bird view.

Well, I still have sth. in mind - I will get back to this topic asap. Will be busy next couple of days, but when I find time I will post my thoughts...

[HornetMaX]

Well that's a good point. But camber thrust does only account for the wheels running towards the interior of the turn, it does not account for the bike pointing towards the outside while running towards the inside.

Theoretically yes, it could: if the front is light, the force on the rear wheel contact patch pushing towards the interior will make the bike "pivot" and point towards the exterior.

For me (and luckily others too) it is even noticeably in standard cameras, on certain tracks and certain turns (e.g. Lucky Heights).

Lucky heights is on a slope (like BOBR6's examples on brands hatch): we already know there's a problem in this kind of turns, this has been agreed a long ago by Piboso (not sure where we stand with respect to that, thought it was a bit better with beta5).

MaX.

[BOBR6 84]

look on klax's latest video... DST practice on laguna in his thread DST adventures.. from about 17 sec into the vid..

[HornetMaX]

look on klax's latest video... DST practice on laguna in his thread DST adventures.. from about 17 sec into the vid..

Turns on a slope (or banked) ==> known problem

MaX.

[BOBR6 84]

lol so this whole topic.... 

[HornetMaX]

lol so this whole topic.... 

The (original) topic was unrelated to what you/Stout and others have reported.
Then the discussion drifted: Stout's video is on a flat turn, so it's interesting. Banked/sloped turns do have an issue, that's clear.

MaX.

[BOBR6 84]

ok 

[WALKEN]

lol so this whole topic.... 

The (original) topic was unrelated to what you/Stout and others have reported.
Then the discussion drifted: Stout's video is on a flat turn, so it's interesting. Banked/sloped turns do have an issue, that's clear.

MaX.

Would you like the thread removed Hornet?