Technical question

[GSVR]

A racetrack is built that is flat. I don't mean smooth I mean perfectly flat without the slighest hint of a bump or elevation change. If someone was to lose a hair off their head it would create a bump. Get the idea.

Now two identical bikes (apart from one difference) are made. One has suspension and one doesn't.
Which bike would technically be able to be ridden the around this racetrack the quickest.
Or to put it another way which bike could be made to go the fastest assuming changes could be made but one bike will always have no springs or dampening.

To look at this another way does the forward and rearward pitching of a bike help it to go any faster? How does the level of grip effect things in this case?

[Shaun]

Obvious Garry- I know even you knowthe awnser to this one your self

[vtec]

I was going to say the one with no suspension. However, come to think about it. Tailslides and front end slips are handled differently on a bike with suspension. So I think a bike with some clever suspension would be better, as it would be more foregiving when right on the edge. I think the more stable weight distribution on a bike with no suspension would be advantageous. But there are still things that need to be absorbed to prevent cutting tyres loose, like say getting on the throttle, would the tyres give enough before letting go?

[MSTRS]

Does the non-suspended bike have to keep the front down at all times...

[Tony.OK]

Tyres are good nowadays, but they ain't that good that they'd cope with 100% of the loads and forces put on them.

[GSVR]

Does the non-suspended bike have to keep the front down at all times...

Good question. Wheelstands are counter productive to going fast so I'd say yes.

[MSTRS]

Good question. Wheelstands are counter productive to going fast so I'd say yes.

Seek no more, for you have your answer.

[Racin Jason]

Ha this cracks me up!

Maybe if the track was a perfect cirlce and robots were riding the bikes the non suspended bike might keep up.

[Racin Jason]

Ha this cracks me up!

Maybe if the track was a perfect cirlce, and robots were riding the bikes to maintain a exact constant optimal speed, the non suspended bike might keep up.

[GSVR]

Does the non-suspended bike have to keep the front down at all times...

My last answer to this may have been a little missleading.

In order to make the assumption that the front wheel will lift you have to assume that the bike is powerful enough to do so and also the level of grip is good enough that the rear doesn't spin up under hard acceleration.

The reason I mention level of grip is that the outcome could be different in lower grip situations.

And of course theres the issue of the rear staying on the ground under heavy braking!

[LBD]

With suspension.....Come into a corner on the front brakes, nose down, Steeper steering angle, tip in quicker than without front suspension. Gas on at the apex, rear down front up bike naturally stands upright.....Would be quicker with suspension in my mind....

[cowpoos]

A racetrack is built that is flat. I don't mean smooth I mean perfectly flat without the slighest hint of a bump or elevation change. If someone was to lose a hair off their head it would create a bump. Get the idea.

Now two identical bikes (apart from one difference) are made. One has suspension and one doesn't.
Which bike would technically be able to be ridden the around this racetrack the quickest.
Or to put it another way which bike could be made to go the fastest assuming changes could be made but one bike will always have no springs or dampening.

To look at this another way does the forward and rearward pitching of a bike help it to go any faster? How does the level of grip effect things in this case?
Whats behind this question??...this is basic basic stuff Gary...a kid in 3rd form would tell you suspesion???

[discotex]

You could ask these guys...

-3ODe9mqoDE

[Robert Taylor]

Whats behind this question??...this is basic basic stuff Gary...a kid in 3rd form would tell you suspesion???

Youve gotta wonder Poos! Pitch forward under braking changes trail and helps to further initiate turn in. Pitch rearwards under power allows the tyre to ''bite the track'' harder and minimise wheel spin. Part of the function of suspension is to allow pitch which helps steering. Little wonder that a mountain bike with suspension can turn tighter than a pushbike without.
Gary, do everyone a favour, dust off your wallet and go and buy textbooks re the subject, or visit the local library.
I think also that bike manufacturers have the basic physics worked out.

[GSVR]

Youve gotta wonder Poos! Pitch forward under braking changes trail and helps to further initiate turn in. Pitch rearwards under power allows the tyre to ''bite the track'' harder and minimise wheel spin. Part of the function of suspension is to allow pitch which helps steering. Little wonder that a mountain bike with suspension can turn tighter than a pushbike without.
Gary, do everyone a favour, dust off your wallet and go and buy textbooks re the subject, or visit the local library.
I think also that bike manufacturers have the basic physics worked out.

No use looking or asking on the internet then?

[Robert Taylor]

No use looking or asking on the internet then?

Textbook material that will give you the answers AT LENGTH are to be found on other forms of internet i.e not this forum. You are effectively asking some poor sod to recite at considerable length because you havent been bothered looking for yourself.
Shaun gave you the best answer, as a prolific reader he would have done his own study, why dont you follow his example.

[GSVR]

With suspension.....Come into a corner on the front brakes, nose down, Steeper steering angle, tip in quicker than without front suspension. Gas on at the apex, rear down front up bike naturally stands upright.....Would be quicker with suspension in my mind....

I would tend to agree with this but I also mentioned the level of grip as this too plays a part I'm thinking.

The closest thing I can think off in the real world (as opposed to my imaginery senario) is longtrack and solo speedway. These bikes have no rear suspension and minimal front suspension and the fastest way to get around the track seems to be in a constant drift.

The pitching of the bike would be of (dare I say it) obvious help at transfering weight to the back of the bike under acceleration but you can have to much of a good thing and this would obviously have an effect on how hard the bike could accelerate under conditions where theres more than enough grip.

Examples of this would be dirtbikes that pitch a large amount to transfer weight back and forth so the wheel that is doing the work has the most weight on it. Or a Fast roadbike being drag raced that has the front forks strapped so as to stop the front end pitching up. These bikes go considerably faster when strapped.

So going back to may first (imaginery senario) post the suspension doesnt have to perform its primary role of absorbing bumps and deviations in the track surface. I made my question this way as I only wanted people to concentrate on the other roles the suspension performs.

I also only used the word "Track" and not circuit as this left the question open for someone to talk about which bike might win a drag race or talk about where/when the bike with suspension may have an advantage.

The whole purpose of the thread was to have some interesting discussion and get some fresh ideas but looking at the replys its been a bit of a disapointment.

Sorry to everyone for asking a stupid question.


Youve gotta wonder Poos! Pitch forward under braking changes trail and helps to further initiate turn in. Pitch rearwards under power allows the tyre to ''bite the track'' harder and minimise wheel spin. Part of the function of suspension is to allow pitch which helps steering. Little wonder that a mountain bike with suspension can turn tighter than a pushbike without.
Gary, do everyone a favour, dust off your wallet and go and buy textbooks re the subject, or visit the local library.
I think also that bike manufacturers have the basic physics worked out.

Who would have thought it. If anyone but an expert had told me that a mountain bike with suspension could turn tighter than a pushbike without I would have laughed. I wonder how much tighter an Ohlins equipped mountain would be able to turn!

To hell with it I'm laughing anyway.

[GSVR]

Textbook material that will give you the answers AT LENGTH are to be found on other forms of internet i.e not this forum. You are effectively asking some poor sod to recite at considerable length because you havent been bothered looking for yourself.
Shaun gave you the best answer, as a prolific reader he would have done his own study, why dont you follow his example.

You assume to much Robert. I'll try and study harder!

[Shaun]

You assume to much Robert. I'll try and study harder!




He can do! But at least he spends the time to try and help on here with silly questions fom some people

[Robert Taylor]

I would tend to agree with this but I also mentioned the level of grip as this too plays a part I'm thinking.

The closest thing I can think off in the real world (as opposed to my imaginery senario) is longtrack and solo speedway. These bikes have no rear suspension and minimal front suspension and the fastest way to get around the track seems to be in a constant drift.

The pitching of the bike would be of (dare I say it) obvious help at transfering weight to the back of the bike under acceleration but you can have to much of a good thing and this would obviously have an effect on how hard the bike could accelerate under conditions where theres more than enough grip.

Examples of this would be dirtbikes that pitch a large amount to transfer weight back and forth so the wheel that is doing the work has the most weight on it. Or a Fast roadbike being drag raced that has the front forks strapped so as to stop the front end pitching up. These bikes go considerably faster when strapped.

So going back to may first (imaginery senario) post the suspension doesnt have to perform its primary role of absorbing bumps and deviations in the track surface. I made my question this way as I only wanted people to concentrate on the other roles the suspension performs.

I also only used the word "Track" and not circuit as this left the question open for someone to talk about which bike might win a drag race or talk about where/when the bike with suspension may have an advantage.

The whole purpose of the thread was to have some interesting discussion and get some fresh ideas but looking at the replys its been a bit of a disapointment.

Sorry to everyone for asking a stupid question.



Who would have thought it. If anyone but an expert had told me that a mountain bike with suspension could turn tighter than a pushbike without I would have laughed. I wonder how much tighter an Ohlins equipped mountain would be able to turn!

To hell with it I'm laughing anyway.

Everyone else is laughing as well, but not with you.

[GSVR]

He can do! But at least he spends the time to try and help on here with silly questions fom some people

I have a great deal of respect for Robert and what he does.

[GSVR]

Everyone else is laughing as well, but not with you.

Your assuming your the spokesman for everyone?

[Robert Taylor]

Your assuming your the spokesman for everyone?

Every one person that asks sensible questions that arent ''loaded'' or twisted to suit a perverse pleasure in winding people up yes. I thank Shaun for expressing that I take the time to answer many questions, many of them indeed stupid. If anyone deliberately sets out to act like a ''cock'' then I guess there will be many people laughing at that person.
There is proof enough that your question was ''silly'' by some of the immediate answers.

[MSTRS]

A racetrack is built that is flat. I don't mean smooth I mean perfectly flat without the slighest hint of a bump or elevation change. If someone was to lose a hair off their head it would create a bump. Get the idea.

Now two identical bikes (apart from one difference) are made. One has suspension and one doesn't.
Which bike would technically be able to be ridden the around this racetrack the quickest.
Or to put it another way which bike could be made to go the fastest assuming changes could be made but one bike will always have no springs or dampening.

To look at this another way does the forward and rearward pitching of a bike help it to go any faster? How does the level of grip effect things in this case?



I also only used the word "Track" and not circuit ...

Forgive us our assumption that you were not talking about a drag strip.

[GSVR]

Forgive us our assumption that you were not talking about a drag strip.


Oh no I've been sprung (excuse the pun). Sorry about that.

I understand why you asked about the front wheel staying on the ground I think. But when I said yes it had too couldn't figure out what "theres your answer" meant.

[GSVR]

Every one person that asks sensible questions that arent ''loaded'' or twisted to suit a perverse pleasure in winding people up yes. I thank Shaun for expressing that I take the time to answer many questions, many of them indeed stupid. If anyone deliberately sets out to act like a ''cock'' then I guess there will be many people laughing at that person.
There is proof enough that your question was ''silly'' by some of the immediate answers.

When I see a silly thread I don't even bother to post on it. Perhaps you could explain why you feel compelled to do the opposite?

Please feel free "not to post" as its not compulsory !

[GSVR]

With suspension.....Come into a corner on the front brakes, nose down, Steeper steering angle, tip in quicker than without front suspension. Gas on at the apex, rear down front up bike naturally stands upright.....Would be quicker with suspension in my mind....

I would tend to agree with this but I also mentioned the level of grip as this too plays a part I'm thinking.

The closest thing I can think off in the real world (as opposed to my imaginery senario) is longtrack and solo speedway. These bikes have no rear suspension and minimal front suspension and the fastest way to get around the track seems to be in a constant drift.

The pitching of the bike would be of (dare I say it) obvious help at transfering weight to the back of the bike under acceleration but you can have to much of a good thing and this would obviously have an effect on how hard the bike could accelerate under conditions where theres more than enough grip.

Examples of this would be dirtbikes that pitch a large amount to transfer weight back and forth so the wheel that is doing the work has the most weight on it. Or a Fast roadbike being drag raced that has the front forks strapped so as to stop the front end pitching up. These bikes go considerably faster when strapped.

So going back to may first (imaginery senario) post the suspension doesnt have to perform its primary role of absorbing bumps and deviations in the track surface. I made my question this way as I only wanted people to concentrate on the other roles the suspension performs.

I also only used the word "Track" and not circuit as this left the question open for someone to talk about which bike might win a drag race or talk about where/when the bike with suspension may have an advantage.

The whole purpose of the thread was to have some interesting discussion and get some fresh ideas but looking at the replys its been a bit of a disapointment.

Some standard rake and trail figures for roadbikes:

SV650 Rake 24.8 degrees Trail 100mm
GSX600 Katana Rake 24 degrees Trail 96mm
K9GSXR1000 Rake 23.8 Trail 98.3mm

[MSTRS]

... solo speedway. These bikes have no rear suspension and minimal front suspension and the fastest way to get around the track seems to be in a constant drift.



Not necessarily. I'm assuming that the almost vertical front forks are to help with stability when tipped in with the front turned out?
<img src=http://www.yorkhospitalradio.com/grasstrack/images/Hinsley%20web%20etc/simon%20vickers%20bike.JPG>

[GSVR]

Yeah that looks berserk. Like the front suspension.

I don't know the rules for these bikes and haven't seen any for a while but ASSUMED that the rules didn't allow rear suspension.

A speedway sidechair builder told me that some places overseas don't allow rear suspension on their sidechairs. Could research it but too lazy.

[MSTRS]

Ah, but side chairs would be different again.

[Robert Taylor]

When I see a silly thread I don't even bother to post on it. Perhaps you could explain why you feel compelled to do the opposite?

Please feel free "not to post" as its not compulsory !

So youre not posting on your own threads.....there have been some reasonable threads youve posted and frankly some downright silly ones.

[Benk]

Dunno about everyone else, but isnt the 'Racing' forum for 'racing' related info?

Shoulndt mooting these useless points be relagated to General Ravings, or basically anywhere other than the Racing forum?

[GSVR]

So youre not posting on your own threads.....there have been some reasonable threads youve posted and frankly some downright silly ones.

And many of your posts seem like either a Kiwibiker sponsored advertisement for CKT or a party political broadcast (Thank fark the elections over).

[GSVR]

Dunno about everyone else, but isnt the 'Racing' forum for 'racing' related info?

Shoulndt mooting these useless points be relagated to General Ravings, or basically anywhere other than the Racing forum?

I'd just send it to PD its already been sabotaged by God. Judas!

[Robert Taylor]

Dunno about everyone else, but isnt the 'Racing' forum for 'racing' related info?

Shoulndt mooting these useless points be relagated to General Ravings, or basically anywhere other than the Racing forum?

I agree, its always a shame when there seems to be either an agenda or a petty vendetta, for what perverse reasons god only knows.
My own personal record stands in having helped a lot of people over the decades in racing circles and a more recent expression of that has been here in print. I make no apology for responding appropriately to anyone who has a smart alec demeanour.
My own vocation has given me a lot of experience and any relevant information is passed on in good spirit, I just dont get why there have to be such people that relish in winding others up.

[Mishy]

A racetrack is built that is flat.............................................. .........
To look at this another way does the forward and rearward pitching of a bike help it to go any faster? How does the level of grip effect things in this case?

:eek: many people have written substantial books on the subject of suspension, and dedicated immense amounts of time in trying to understand EXACTLY what goes on with suspension behaviour, and how to use it to progress laptimes. It is TOTALLY fair to say that you will not get a complete definitive answer via a forum, nor by many publications, so i have to say - good on you for wondering, but the answers will require a LOT more thought, effort and investigation.

I started making an effort to get an understanding of what makes it all tick a few years ago, and am STILL discovering how little I really do know about why/how, and how much, despite the fact that i have learnt quite a bit (Robert will testify to the volume of "silly questions" and "crazy ideas")

It's complicated, and once you start it will comsume you
If you are still keen, seek psycological help my friend :eek:

[t3mp0r4ry nzr]

am I crazy to wonder of the merit of a "speedway" type bike set-up for the circuit. it would need plenty of torque to break traction at will to "steer with the rear" at high speed? I probabley am, cos circuits are'nt perfectly smooth so its wasted thought. mind you drift cars usually have rudementary suspention to stop weight transfer to ultimately reduce traction (?) to create slip. with the inherent instability of a 2 wheeled machine, this probabley isnt the best or fastest way around a circuit even if perfectly smooth.

[MSTRS]

am I crazy to wonder of the merit of a "speedway" type bike set-up for the circuit. it would need plenty of torque to break traction at will to "steer with the rear" at high speed? I probabley am, cos circuits are'nt perfectly smooth so its wasted thought. mind you drift cars usually have rudementary suspention to stop weight transfer to ultimately reduce traction (?) to create slip. with the inherent instability of a 2 wheeled machine, this probabley isnt the best or fastest way around a circuit even if perfectly smooth.

This would tend to illustrate the reason why suspension is important. It's primary function is to keep the tyres in contact with the road/track/whatever. Without it, the tyres will deform slightly (would anyway?) providing a tiny bit of 'suspension', but not possible to provide enough. With a rigid rear, it would be hard (sic!) to keep the front down under hard acceleration, and heavy braking would definitely be interesting. Cornering without drifting would be almost impossible. Both would slow you down.

[GSVR]

:eek: many people have written substantial books on the subject of suspension, and dedicated immense amounts of time in trying to understand EXACTLY what goes on with suspension behaviour, and how to use it to progress laptimes. It is TOTALLY fair to say that you will not get a complete definitive answer via a forum, nor by many publications, so i have to say - good on you for wondering, but the answers will require a LOT more thought, effort and investigation.

I started making an effort to get an understanding of what makes it all tick a few years ago, and am STILL discovering how little I really do know about why/how, and how much, despite the fact that i have learnt quite a bit (Robert will testify to the volume of "silly questions" and "crazy ideas")

It's complicated, and once you start it will comsume you
If you are still keen, seek psycological help my friend :eek:

Thanks for your reply. I spend way too much time thinking about many aspects of what makes a racebike tick. Weather it be suspension, engines, weight distribution, electronic aids, rider psycology, fitness and diet, tyres, support crews, aerodymanics, etc. the list is endless.

One method I use to make decisions on what are major factors or not is to break a problem down into easy to understand parts. Hence the dead flat track in this case.

I can see that when hard on the brakes if the front end dives by any amount this will lower the bikes center of gravity and make it possible to brake harder before the rear wheel lifts. And of course all bikes do this the trick is for the suspension not to bottom out!
I can also see the same effect under hard acceleration but if the front is sprung then its going to raise unless its already topped out.

The changes in rake and trail when the bike pitches I see as being a negative effect. If the pitching of the bike is minimal or doesn't happen when the bike is trying to be steered then its not a problem. The trail being the biggest issue because as soon as it becomes negative the bike is unstable.

The level of grip and power of the the engines and brakes are possibly the most important factors in deciding if the non suspended bike could be faster than a suspended one.

Say that the bikes do not have enough power to pull a wheelstand and cannot achieve hard enough braking to lift the rear wheel. This would then isolate the grip factor somewhat.
Lets say that the grip is 100 percent (ie. not loss of traction whatsoever) Then possibly both bikes may even lap at exactly the same pace or some other aspect of the problem I have overlooked become apparent!

One thing I do know is the rake and trail of the rigid bike would be able to be set very accurately.

Anyway when you stop about thinking how to go faster your've either given up or your paying/getting someone else to think for you!

[GSVR]

This would tend to illustrate the reason why suspension is important. It's primary function is to keep the tyres in contact with the road/track/whatever. Without it, the tyres will deform slightly (would anyway?) providing a tiny bit of 'suspension', but not possible to provide enough. With a rigid rear, it would be hard (sic!) to keep the front down under hard acceleration, and heavy braking would definitely be interesting. Cornering without drifting would be almost impossible. Both would slow you down.

Example of rigid rear end may be Top Fuel Dragsters again its all about levels of grip/traction

[Robert Taylor]

This would tend to illustrate the reason why suspension is important. It's primary function is to keep the tyres in contact with the road/track/whatever. Without it, the tyres will deform slightly (would anyway?) providing a tiny bit of 'suspension', but not possible to provide enough. With a rigid rear, it would be hard (sic!) to keep the front down under hard acceleration, and heavy braking would definitely be interesting. Cornering without drifting would be almost impossible. Both would slow you down.

Yes, controlled pitch and weight transfer is neccessary to initiate turn in and to assist exit grip. Theres obviously a lot more to it than that but thats the important bits. Also when relating to speedway the surface is obviously loose and chops up. I dont know what the construction of speedway tyres is with respect to sidewall stiffness and carcass construction.

[Robert Taylor]

Thanks for your reply. I spend way too much time thinking about many aspects of what makes a racebike tick. Weather it be suspension, engines, weight distribution, electronic aids, rider psycology, fitness and diet, tyres, support crews, aerodymanics, etc. the list is endless.

One method I use to make decisions on what are major factors or not is to break a problem down into easy to understand parts. Hence the dead flat track in this case.

I can see that when hard on the brakes if the front end dives by any amount this will lower the bikes center of gravity and make it possible to brake harder before the rear wheel lifts. And of course all bikes do this the trick is for the suspension not to bottom out!
I can also see the same effect under hard acceleration but if the front is sprung then its going to raise unless its already topped out.

The changes in rake and trail when the bike pitches I see as being a negative effect. If the pitching of the bike is minimal or doesn't happen when the bike is trying to be steered then its not a problem. The trail being the biggest issue because as soon as it becomes negative the bike is unstable.

The level of grip and power of the the engines and brakes are possibly the most important factors in deciding if the non suspended bike could be faster than a suspended one.

Say that the bikes do not have enough power to pull a wheelstand and cannot achieve hard enough braking to lift the rear wheel. This would then isolate the grip factor somewhat.
Lets say that the grip is 100 percent (ie. not loss of traction whatsoever) Then possibly both bikes may even lap at exactly the same pace or some other aspect of the problem I have overlooked become apparent!

One thing I do know is the rake and trail of the rigid bike would be able to be set very accurately.

Anyway when you stop about thinking how to go faster your've either given up or your paying/getting someone else to think for you!

We have dvds available for sale that explain some of that. You should also look at purchasing a copy of Tony Foales book, it will answer all of your questions and some.

[MSTRS]

Example of rigid rear end may be Top Fuel Dragsters again its all about levels of grip/traction

Yeah, but aren't we talking about bikes? You know...those unstable 2 wheeled death machines?
Anyway, even Rails can wheelstand if the driver gets it wrong.

[GSVR]

I'm still talking about the perfectly flat track here.

So we have established that the people in the know believe that the bike with suspension will be faster because it can pitch back and forth to provide better steering and corner exit amounst other things.

Now lets say just so things don't get too radical that the bike is based on the latest GSXR1000.

How much suspension travel would you need for the perfectly flat track?
How far would you setup the bike to pitch?
How does the level of grip effect this?

Be careful as I don't want to be accused of having leading questions!

[Benk]

*Loads gun, blows own brains out*

[cowpoos]

*Loads gun, blows own brains out*
can i have your bike?

[Benk]

No worries, you can be the first to try it with my new suspension. I have got rid of springs and oil and shit, and just wedged a couple of bits of wood in there. Saved myself some weight, and will be able to do at least 1:42's round Taupo, by steering with the rear wheel and running 5psi of air in the tyres. You should be able to manage 1:41's easily. I mean, if my skill level was hypothetically perfect, then this shouldnt be a problem at all.

Infact, bugger it. Ill just hover 2 inches above the track. Im hoping this will allow me to remove my tyres altogether.

*Throws new wooden suspension concept on the fire. Wont be needed, will be too busy hovering*

[GSVR]

*Loads gun, blows own brains out*

What you justed realised your riding a Honda?

[GSVR]

I'm still talking about the perfectly flat track here.

So we have established that the people in the know believe that the bike with suspension will be faster because it can pitch back and forth to provide better steering and corner exit amounst other things.

Now lets say just so things don't get too radical that the bike is based on the latest GSXR1000.

1/How much suspension travel would you need for the perfectly flat track?
2/How far would you setup the bike to pitch?
3/How does the level of grip effect this?

Be careful as I don't want to be accused of having leading questions!

I'll have a go and Robert or someone thats not disruptive can explain if I have it right!

1/The same as for a bumpy track
2/Depends on the type of corners eg sharp then opening or sweepers into sharps.
3/ The more grip the stiffer I'd make the suspension.

Sorry this isn't entirely my answer its how I imagine some other person might answer.

[Benk]

What you justed realised your riding a Honda?

Ohhhh I get it now. Thats hilarious!

[Mishy]

How much suspension travel would you need for the perfectly flat track?
How far would you setup the bike to pitch?
How does the level of grip effect this?

Be careful as I don't want to be accused of having leading questions!


Now you need to tell us how fast the corners are, how long they are, what the riders preferred feel is ( notwithstanding the pretty blonde at the end of the bar) and a whole heap of other stuff that matters too. All this stuff (except the blonde) will have some sort of influence on spring rate, sag, preload, rideheight etc etc, and there is seldom a "perfect answer" only a better compromise. i can think of a heap of reasons why your stick suspension bike would suck, but it just takes too long to type all that shit - just trust me, it'd suck ass big time.

tyres don't like bad suspension or geometry either. They need enough load at the right time, and not more or less, otherwise they are not at their best. carcasses deform all over in normal riding, and they also happen to be a dampened spring themselves, so they can pass force back into the suspension. the light/heavy cycle of a tyre compressing and rebounding would probably be a nightmare on an unsuspended bike all on it's own.

You need to read the Foale book - you will REALLY enjoy it :2thumbsup

[Robert Taylor]

Now you need to tell us how fast the corners are, how long they are, what the riders preferred feel is ( notwithstanding the pretty blonde at the end of the bar) and a whole heap of other stuff that matters too. All this stuff (except the blonde) will have some sort of influence on spring rate, sag, preload, rideheight etc etc, and there is seldom a "perfect answer" only a better compromise. i can think of a heap of reasons why your stick suspension bike would suck, but it just takes too long to type all that shit - just trust me, it'd suck ass big time.

tyres don't like bad suspension or geometry either. They need enough load at the right time, and not more or less, otherwise they are not at their best. carcasses deform all over in normal riding, and they also happen to be a dampened spring themselves, so they can pass force back into the suspension. the light/heavy cycle of a tyre compressing and rebounding would probably be a nightmare on an unsuspended bike all on it's own.

You need to read the Foale book - you will REALLY enjoy it :2thumbsup

Good answer, and the reality is that you couldnt lay exact figures, that is one compelling reason race teams do lots of testing. To try different settings and end up with the best setting ( with what youve got to work with ) to get round the track as fast as possible and save the tyres. This would also apply on a totally smooth totally bump free surface, were there such a surface, anywhere.
Although it may sound counterintuitive smoother race tracks tend to require softer settings to actually get the chassis to move more to find grip. Bumpy race tracks require more ''slope'' on the high speed damping to catch sudden movements.That is from my own experience. Purchase the Foale book.

[Mishy]

.....................wedged a couple of bits of wood in there. Saved myself some weight,...

Stick with the wood :) Winters on the way, and you could just pull the "suspension" at the end of the day and burn it to get warm !

[Mishy]

Although it may sound counterintuitive smoother race tracks tend to require softer settings to actually get the chassis to move more to find grip.

Funny, huh ? It seems to be all about getting the suspension to control the balance of load aplied to either tyre, and having enough spring to transfer that load to the tyre (and therefor the contact patch) without soaking it all up in the damper. That would be how we use suspension to influence "mechanical traction" I believe :yes:
What are your thoughts on that ?

[Robert Taylor]

Funny, huh ? It seems to be all about getting the suspension to control the balance of load aplied to either tyre, and having enough spring to transfer that load to the tyre (and therefor the contact patch) without soaking it all up in the damper. That would be how we use suspension to influence "mechanical traction" I believe :yes:
What are your thoughts on that ?

Therby achieving maximum possible ''pavement interlock'' and minimise any chance of ''dry aquaplaning'' !!!!!!!!!!!!!!!!!!!!!!!!!!

[Mishy]

Therby achieving maximum possible ''pavement interlock''


Souns like a woman i met once . . . .. . . . . . . . . . . :msn-wink:

[GSVR]

Thanks for the replys I'll have another go at answering my own questions again.


1a/How much suspension travel would you need for the perfectly flat track?
1b/How far would you setup the bike to pitch?
1c/How does the level of grip effect this?

1a/ Suspension travel is not solely for absorbing bumps it also aids in the transfer of weight between the tyres and changes the wheelbase and geometry of the bike as well as other stuff to technical to go into at length. The amount of suspension travel the manufacturer has built into the bike is probably right. After all its a GSXR with years of development.

1b/ Way to complicated to answer without all of the information about the track,rider,conditions,tyres,bike etc. Are you asking if I'd use all of the available travel? Or if there was more grip I would have the bike pitch less for any given set of other conditions?

1c/ Grip is something you can never have to much of. The whole point of suspension in roadracing is to maintain maximum grip between the track and tyres.

Tyre carcass is a very interesting subject at the moment with manufacturers taking different approachs. This alone requires very different suspension settings.

Possibly a stick bike would require solid tyres to improve its bad performance! Forget the stick bike please. The question is only concerning areal world example namely GSXR1000K9 (apart from the perfectly flat track of course).

[roogazza]

Gary, was just having a read of this thread and a bit of a giggle about how it was say, 35 years ago. With a Mach4 for example, to get them round a race track we would stick packers in the front of about 1 inch and for oil , engine oil like castrol XL 30/40 ! At the rear we just shoved the units on the hardest setting (no sag in those days mate !) A set of TT100s' and away you went.
Brings a smile to hear of all the stuff you have to do today. Gaz.

[GSVR]

http://www.tonyfoale.com/

Thought the name sounded familiar. Been to this site recently when researching another motorcycle matter.

What do you think of the bike with hardly any rake and alot of offset?. He reacons its a possible winner. Or at least he did when he wrote the article. One of its percieved advantages was less front end dive!


Gary, was just having a read of this thread and a bit of a giggle about how it was say, 35 years ago. With a Mach4 for example, to get them round a race track we would stick packers in the front of about 1 inch and for oil , engine oil like castrol XL 30/40 ! At the rear we just shoved the units on the hardest setting (no sag in those days mate !) A set of TT100s' and away you went.
Brings a smile to hear of all the stuff you have to do today. Gaz.

I suppose some might consider this to be the Golden Era of motorcycle racing. Interesting how Formula 1 seems to be heading backwards technically but if the first GP this year is anything to go by this may be a very good year for specators and drivers alike.

Regenerative braking is something I like that is high tech and I can see how it will aid cars and possibly then bikes of the future.

[Robert Taylor]

Thanks for the replys I'll have another go at answering my own questions again.


1a/How much suspension travel would you need for the perfectly flat track?
1b/How far would you setup the bike to pitch?
1c/How does the level of grip effect this?

1a/ Suspension travel is not solely for absorbing bumps it also aids in the transfer of weight between the tyres and changes the wheelbase and geometry of the bike as well as other stuff to technical to go into at length. The amount of suspension travel the manufacturer has built into the bike is probably right. After all its a GSXR with years of development.

1b/ Way to complicated to answer without all of the information about the track,rider,conditions,tyres,bike etc. Are you asking if I'd use all of the available travel? Or if there was more grip I would have the bike pitch less for any given set of other conditions?

1c/ Grip is something you can never have to much of. The whole point of suspension in roadracing is to maintain maximum grip between the track and tyres.

Tyre carcass is a very interesting subject at the moment with manufacturers taking different approachs. This alone requires very different suspension settings.

Possibly a stick bike would require solid tyres to improve its bad performance! Forget the stick bike please. The question is only concerning areal world example namely GSXR1000K9 (apart from the perfectly flat track of course).

You just cannot pluck totally specific figures out and thats why I posted about such things being exhaustively tested. Sometimes the setup can deviate substanially from pre-theory. Suffice to say a road race bike on many smooth Euro GP circuits may only use up to a third of its travel, a wee bit of moderate bump absorption but mainly to get it to pitch fore and aft for the reasons I put forward in a previous post. Indeed Superbikes have to pitch more than 600s and a lot more than 250s / 125s because they have so much power. They need weight transfer to minimise spin and maximise grip.
Youd only use close to all of the available travel on notorious circuits such as Pukekohe ( and the street circuits ) because the bumps and g outs incur that. Suspension shaft velocities on that track are up around 800mm/second in turn 1. Nasty and dangerous.
In Formula Ford racing it is not uncommon to tune out excessive grip to either balance the car or to compensate for there not being enough power to pull the skin off a rice pudding.
If the surface is wet you soften off the spring and clicker settings to allow it to more so ''mechanically pitch'' as you cannot feed in engine power so readily to make it do so, etc.

[Robert Taylor]

Gary, was just having a read of this thread and a bit of a giggle about how it was say, 35 years ago. With a Mach4 for example, to get them round a race track we would stick packers in the front of about 1 inch and for oil , engine oil like castrol XL 30/40 ! At the rear we just shoved the units on the hardest setting (no sag in those days mate !) A set of TT100s' and away you went.
Brings a smile to hear of all the stuff you have to do today. Gaz.

And weld up the hinge in the middle? I remember seeing Ray or Alan ( ? ) Collison wobbling around Pukekohe on those widowmakers.

[Robert Taylor]

http://www.tonyfoale.com/

Thought the name sounded familiar. Been to this site recently when researching another motorcycle matter.

What do you think of the bike with hardly any rake and alot of offset?. He reacons its a possible winner. Or at least he did when he wrote the article. One of its percieved advantages was less front end dive!



I suppose some might consider this to be the Golden Era of motorcycle racing. Interesting how Formula 1 seems to be heading backwards technically but if the first GP this year is anything to go by this may be a very good year for specators and drivers alike.

Regenerative braking is something I like that is high tech and I can see how it will aid cars and possibly then bikes of the future.

That Tony Foale book is in my library and I havent read it yet. Ho hum.

Formula 1 is something Ive followed since I was a kid and I thought the mid to late 60s were the golden era, a little bit anachronistic to some of my other views.
Its an interesting field, theres a lot of technology and very fertile thinking going on in spite of constant rule changes. It always amazes me looking at the slow mos of the cars banging over the kerbs while cutting through chicanes. It is so violent and rather suggests that in suspension terms the cars are little beter than go karts but with no chassis flex. Its rather lucky they have tall aspect ratio sidewalls otherwise theyd need suspension that actually moves!
The reason of course they are so rigid is because first and foremost the chassis / suspension setup has to be almost totally subservient to aero function and balance.Flat bottom cars with diffusers need to essentially keep the underside as parrallell and as low to the ground as possible while cornering to assist in creating maximum possible downforce and therefore grip. In straight line situations there must be some very strictly controlled pitch so that positive benefits can be gained from downforce migration from one end of the car to the other to assist in braking and exit grip etc.
Even here in NZ downforce and management of chassis attitude is critical on our humble Toyota racing series cars. The spring rates are huge and we had to instal some reasonably aggressive damping. At low speed when there is no downforce ( exiting pits etc ) you may as well be riding in a block dray.

[roogazza]

And weld up the hinge in the middle? I remember seeing Ray or Alan ( ? ) Collison wobbling around Pukekohe on those widowmakers.

Yes, it was Alan,very strong guy as I recall, all that moto X, huh ? (guess that helped, he was the man to beat for a long time). Gaz.