Technical question

[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

[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

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
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
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 . . . .. . . . . . . . . . .

[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.