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jonlampert
02-15-2003, 12:35 AM
I have yet to see any info or discussion about tire pressures. Does anyone out there have a good knowledge of appropriate tire pressures for different weather (50deg ambient vs 95deg ambient), tracks, tires, etc. How does the tire pressure affect the handling of the bike? If you have tire warmers, should you set the pressure when the tires are hot? Any info on this subject would be much appreciated. Currently, I have almost no idea where to set the pressures, aside from "about 30 psi or so".

jonlampert
02-15-2003, 12:35 AM
I have yet to see any info or discussion about tire pressures. Does anyone out there have a good knowledge of appropriate tire pressures for different weather (50deg ambient vs 95deg ambient), tracks, tires, etc. How does the tire pressure affect the handling of the bike? If you have tire warmers, should you set the pressure when the tires are hot? Any info on this subject would be much appreciated. Currently, I have almost no idea where to set the pressures, aside from "about 30 psi or so".

racer550
02-15-2003, 01:52 AM
I always ask the guy who sold me the tires. I usually buy them at the track, but if you bought them in advance, just ask the dealer who carries the brand you are using. Each brand has different characteristics which will affect the optimum psi.
/ubbthreads/images/%%GRAEMLIN_URL%%/eek.gif

racer550
02-15-2003, 01:52 AM
I always ask the guy who sold me the tires. I usually buy them at the track, but if you bought them in advance, just ask the dealer who carries the brand you are using. Each brand has different characteristics which will affect the optimum psi.
/ubbthreads/images/%%GRAEMLIN_URL%%/eek.gif

Jeff Grant
02-15-2003, 09:22 PM
For what it's worth, here is what I was told and what worked for me. From my Pirelli/Metzler and Dunlop 208GP experience...

Of course, these numbers are all suggested when the tires are cold.

Pirelli/Metzeler-warmer/hot climate
Front, 31
Rear, 30

Pirelli/Metzeler-Cooler/cold climate
Front, 32
Rear, 31

Dunlop 208GP-warmer/hot climate
Front, 31
Rear, 29.5

Dunlop 208GR-cooler/cold climate
Front, 32
Rear, 30.5

I've never ran Michelins, so you'll want to get with David Hirsch @ Island Racing.

Since the rear tire is obviously the drive tire, it will generate a little more heat and expand more, ergo, having the rear tire psi -1 from the front.

Hot tire pressure should be taken immediately after you get off the track in order to get a more accurate reading. On a warmer day, tire pressure can rise 3 to 4 psi. After you get off the track, take your tire pressure. 34 to 36 psi when hot is a good general range.

If you set your front to 31 cold and 30 rear cold, go out and do a solid session/practice, then take your hot tire pressure. The goal is to be around 35 psi. If your hot tire pressure is only around 33, then you know that you're not getting enough heat into the tire... therefore, you should raise your initial COLD tire pressure by 1 psi.

Then repeat.

I realize that some tire manufacturers suggest different hot psi levels for "otpimized performance". From what I know, between 34 and 36 psi is the goal.

My $.02 Hope this made sense.

Jeff Grant
02-15-2003, 09:22 PM
For what it's worth, here is what I was told and what worked for me. From my Pirelli/Metzler and Dunlop 208GP experience...

Of course, these numbers are all suggested when the tires are cold.

Pirelli/Metzeler-warmer/hot climate
Front, 31
Rear, 30

Pirelli/Metzeler-Cooler/cold climate
Front, 32
Rear, 31

Dunlop 208GP-warmer/hot climate
Front, 31
Rear, 29.5

Dunlop 208GR-cooler/cold climate
Front, 32
Rear, 30.5

I've never ran Michelins, so you'll want to get with David Hirsch @ Island Racing.

Since the rear tire is obviously the drive tire, it will generate a little more heat and expand more, ergo, having the rear tire psi -1 from the front.

Hot tire pressure should be taken immediately after you get off the track in order to get a more accurate reading. On a warmer day, tire pressure can rise 3 to 4 psi. After you get off the track, take your tire pressure. 34 to 36 psi when hot is a good general range.

If you set your front to 31 cold and 30 rear cold, go out and do a solid session/practice, then take your hot tire pressure. The goal is to be around 35 psi. If your hot tire pressure is only around 33, then you know that you're not getting enough heat into the tire... therefore, you should raise your initial COLD tire pressure by 1 psi.

Then repeat.

I realize that some tire manufacturers suggest different hot psi levels for "otpimized performance". From what I know, between 34 and 36 psi is the goal.

My $.02 Hope this made sense.

David Branyon
02-27-2003, 07:28 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Jeff Grant:
<snip>
If you set your front to 31 cold and 30 rear cold, go out and do a solid session/practice, then take your hot tire pressure. The goal is to be around 35 psi. If your hot tire pressure is only around 33, then you know that you're not getting enough heat into the tire... therefore, you should raise your initial COLD tire pressure by 1 psi.
<snip></div></div>Jeff,
Thanks for all the wonderful info, but I am a bit confused as I thought this last part was backwards. Agree that if the tire pressure is not rising enough from cold to hot that you are not getting enough heat into the tire. But shouldn't you LOWER the cold pressure then, to get more tire flex and therefore more heat into the tire? (Slightly larger resultant footprint will also help get more heat into the tire.)

Help me out, O great one. /ubbthreads/images/%%GRAEMLIN_URL%%/cool.gif
Seriously, I'd like to get straight on this one.

Thanks,

David Branyon
02-27-2003, 07:28 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Jeff Grant:
<snip>
If you set your front to 31 cold and 30 rear cold, go out and do a solid session/practice, then take your hot tire pressure. The goal is to be around 35 psi. If your hot tire pressure is only around 33, then you know that you're not getting enough heat into the tire... therefore, you should raise your initial COLD tire pressure by 1 psi.
<snip></div></div>Jeff,
Thanks for all the wonderful info, but I am a bit confused as I thought this last part was backwards. Agree that if the tire pressure is not rising enough from cold to hot that you are not getting enough heat into the tire. But shouldn't you LOWER the cold pressure then, to get more tire flex and therefore more heat into the tire? (Slightly larger resultant footprint will also help get more heat into the tire.)

Help me out, O great one. /ubbthreads/images/%%GRAEMLIN_URL%%/cool.gif
Seriously, I'd like to get straight on this one.

Thanks,

Ronnie
03-01-2003, 01:08 PM
Primary tire air pressure variables :

1) environmental temp
2) bike/rider weight
3) tire age

-The lower the tire pressure, the more heat generated due to tire sidewall flex.

-The lower the environmental temp. the lower the tire pressure (>50f 26-28 in front and 24-26 in rear) On the hottest summer days, 30-32 in front and 28-30 in rear. These numbers pertain to a Ducati M750 racebike using Michelin slicks and a 150 pound rider fully geared and dripping wet.

More "used up" tires require more air pressure as they tend to overheat quicker.

In my experience, adding/subtracting even one pound often makes a noteable difference. You will obviously need to experiment. You will know when your tires are overheated as the bike will losen up considerably.

I know a motard rider that runs 15lbs front and rear (flyweight bike).

Hope this helps.

Ronnie Gyure - Ex #60

Ronnie
03-01-2003, 01:08 PM
Primary tire air pressure variables :

1) environmental temp
2) bike/rider weight
3) tire age

-The lower the tire pressure, the more heat generated due to tire sidewall flex.

-The lower the environmental temp. the lower the tire pressure (>50f 26-28 in front and 24-26 in rear) On the hottest summer days, 30-32 in front and 28-30 in rear. These numbers pertain to a Ducati M750 racebike using Michelin slicks and a 150 pound rider fully geared and dripping wet.

More "used up" tires require more air pressure as they tend to overheat quicker.

In my experience, adding/subtracting even one pound often makes a noteable difference. You will obviously need to experiment. You will know when your tires are overheated as the bike will losen up considerably.

I know a motard rider that runs 15lbs front and rear (flyweight bike).

Hope this helps.

Ronnie Gyure - Ex #60

jonlampert
03-01-2003, 07:12 PM
OK, now we have two contradictory posts. Jeff says that in a hotter climate, run LESS pressure in your tires. Ronnie says that in a hotter climate, run MORE pressure in your tire. I understand you are both making statements about specific tire brands and models, but one would think that in general, you would do the same for any tire. Maybe that is not the case. Does anyone know for sure?

jonlampert
03-01-2003, 07:12 PM
OK, now we have two contradictory posts. Jeff says that in a hotter climate, run LESS pressure in your tires. Ronnie says that in a hotter climate, run MORE pressure in your tire. I understand you are both making statements about specific tire brands and models, but one would think that in general, you would do the same for any tire. Maybe that is not the case. Does anyone know for sure?

Ronnie
03-01-2003, 08:17 PM
Wow, I had not noticed that my advice, with regard to environmental temp 'v' tire pressure, contradicted Jeff's untill you pointed it out. With all due respect to Jeff, I strongly disagree with his temp/air pressure reasoning. Think about it. The lower the tire pressure, the more sidewall flex (the primary source of generated heat) and thus, a quicker heating and hotter tire. So if you want your tire to heat more and more quickly, (on cold days) one would run less air pressure. The opposite is true for hot days. My info is based upon six years of careful racetrack experimentation and in-depth discussions with Ottis Lance (a 25+ year roadrace veteran who is very bright when it comes to all things motorcycle).

Ronnie

Ronnie
03-01-2003, 08:17 PM
Wow, I had not noticed that my advice, with regard to environmental temp 'v' tire pressure, contradicted Jeff's untill you pointed it out. With all due respect to Jeff, I strongly disagree with his temp/air pressure reasoning. Think about it. The lower the tire pressure, the more sidewall flex (the primary source of generated heat) and thus, a quicker heating and hotter tire. So if you want your tire to heat more and more quickly, (on cold days) one would run less air pressure. The opposite is true for hot days. My info is based upon six years of careful racetrack experimentation and in-depth discussions with Ottis Lance (a 25+ year roadrace veteran who is very bright when it comes to all things motorcycle).

Ronnie

Keith Hertell
03-01-2003, 08:21 PM
Ronnie wins the prize!!! http://freeconservatives.com/smilies/beerchug.gif

Keith Hertell
03-01-2003, 08:21 PM
Ronnie wins the prize!!! http://freeconservatives.com/smilies/beerchug.gif

Jeff Grant
03-01-2003, 11:06 PM
Sorry that I didn't come across correctly... but at least I got the juices flowin'. /ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

I was thinking more along the lines of hot temp with my input, and what works for me. Meaning, if it's hot out, but you're PSI is still a little low, then raising your tire's PSI a pound or two in order to obtain "optimal" PSI has worked for me. From what I've learned, a tire that has lower PSI on a hot day can get TOO hot and get greasy/lose traction.

I agree that if it's cold out, then lower the the PSI, to generate more heat that would normally be reached on a hot day. Feedback seems to be a little "off" initially, but that should change once you get up to temp.

Anyway... I'll be quite now. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

Jeff Grant
03-01-2003, 11:06 PM
Sorry that I didn't come across correctly... but at least I got the juices flowin'. /ubbthreads/images/%%GRAEMLIN_URL%%/smile.gif

I was thinking more along the lines of hot temp with my input, and what works for me. Meaning, if it's hot out, but you're PSI is still a little low, then raising your tire's PSI a pound or two in order to obtain "optimal" PSI has worked for me. From what I've learned, a tire that has lower PSI on a hot day can get TOO hot and get greasy/lose traction.

I agree that if it's cold out, then lower the the PSI, to generate more heat that would normally be reached on a hot day. Feedback seems to be a little "off" initially, but that should change once you get up to temp.

Anyway... I'll be quite now. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

marcus mcbain
03-02-2003, 09:39 PM
Let me really screw this topic up and recommend the following:

1) Many experienced tuners will recommend adding/dropping a pound or two of air to fine tune bike suspension handling/feel.

2) There is a "zone" for each radial tire that provides optimal operation of the tire. Too much or two little pressure distorts the carcass of the tire and creates an unstable/unpredictable situation.

3) Because of this, I don't recommend dropping the pressure more than 1.5psi from the factory recommendations. RATHER, take a line out of your preload (front) and one turn of spring out the rear. This will allow the suspension to be more forgiving for tires that don't want to stick on 34 degree mornings.

4) Lastly, cooking tires on tire warmers for an hour will solve your problems. Most people think that because the surface temperature is cool that the tires are not warm. Tire warmers help the core temperature more than anything else. This includes warming the "rubber" around the carcass so the tire can work properly. This may not be noticeable to the hand, but feel how warm the rims are when you come in.

5) Good luck.

Marcus

marcus mcbain
03-02-2003, 09:39 PM
Let me really screw this topic up and recommend the following:

1) Many experienced tuners will recommend adding/dropping a pound or two of air to fine tune bike suspension handling/feel.

2) There is a "zone" for each radial tire that provides optimal operation of the tire. Too much or two little pressure distorts the carcass of the tire and creates an unstable/unpredictable situation.

3) Because of this, I don't recommend dropping the pressure more than 1.5psi from the factory recommendations. RATHER, take a line out of your preload (front) and one turn of spring out the rear. This will allow the suspension to be more forgiving for tires that don't want to stick on 34 degree mornings.

4) Lastly, cooking tires on tire warmers for an hour will solve your problems. Most people think that because the surface temperature is cool that the tires are not warm. Tire warmers help the core temperature more than anything else. This includes warming the "rubber" around the carcass so the tire can work properly. This may not be noticeable to the hand, but feel how warm the rims are when you come in.

5) Good luck.

Marcus

Rich Desmond
03-02-2003, 10:23 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Marcus McBain:
Let me really screw this topic up and recommend the following:

1) Many experienced tuners will recommend adding/dropping a pound or two of air to fine tune bike suspension handling/feel.

2) There is a "zone" for each radial tire that provides optimal operation of the tire. Too much or two little pressure distorts the carcass of the tire and creates an unstable/unpredictable situation.

3) Because of this, I don't recommend dropping the pressure more than 1.5psi from the factory recommendations. RATHER, take a line out of your preload (front) and one turn of spring out the rear. This will allow the suspension to be more forgiving for tires that don't want to stick on 34 degree mornings.

4) Lastly, cooking tires on tire warmers for an hour will solve your problems. Most people think that because the surface temperature is cool that the tires are not warm. Tire warmers help the core temperature more than anything else. This includes warming the "rubber" around the carcass so the tire can work properly. This may not be noticeable to the hand, but feel how warm the rims are when you come in.

5) Good luck.

Marcus</div></div>uuhhh, Marcus, changing pre-load does NOT change spring rate, at least not in the way that you are implying. At the front it only affects sag, pre-load has zero effect on rate. At the rear, with a stock linkage, taking out pre-load can actually make the rear end stiffer.

Rich Desmond
03-02-2003, 10:23 PM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Marcus McBain:
Let me really screw this topic up and recommend the following:

1) Many experienced tuners will recommend adding/dropping a pound or two of air to fine tune bike suspension handling/feel.

2) There is a "zone" for each radial tire that provides optimal operation of the tire. Too much or two little pressure distorts the carcass of the tire and creates an unstable/unpredictable situation.

3) Because of this, I don't recommend dropping the pressure more than 1.5psi from the factory recommendations. RATHER, take a line out of your preload (front) and one turn of spring out the rear. This will allow the suspension to be more forgiving for tires that don't want to stick on 34 degree mornings.

4) Lastly, cooking tires on tire warmers for an hour will solve your problems. Most people think that because the surface temperature is cool that the tires are not warm. Tire warmers help the core temperature more than anything else. This includes warming the "rubber" around the carcass so the tire can work properly. This may not be noticeable to the hand, but feel how warm the rims are when you come in.

5) Good luck.

Marcus</div></div>uuhhh, Marcus, changing pre-load does NOT change spring rate, at least not in the way that you are implying. At the front it only affects sag, pre-load has zero effect on rate. At the rear, with a stock linkage, taking out pre-load can actually make the rear end stiffer.

marcus mcbain
03-02-2003, 10:47 PM
That is pretty impressive information coming from someone that has told me throttle is used to adjust rebound and compression /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif (OK it was actually Scott /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif )

Actaully you are somewhat correct (But only in the most extreme situation). If you soften the spring too much, then the comrpession/rebound would need to be softened up or the corresponding spring/damping rates would be hosed. (This is what would support your "stiffer" scenario) From what I have experienced (personally and from people paying me money to set their suspension up) 1 line (front) and one turn (rear) will not put your settings "out of whack". NOW, if you suspension is hosed up in the first place, I can't do anything for you on that /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

The real important issue here is that I have seen quite a few knuckleheads drop the air pressure 3 or more pounds on the rires, and this AIN'T the hot ticket.

NOW, THEORY and PRACTICE in action - You can go on this BBS or the WERA BBS and see all kinds of opinions on suspension. Everyone has an theory/opinion based off of linkage rates, etc. THE REAL WORLD swallows those opinions like rice in Ethiopia. I have a couple of race winners that I did the "fine" tuning on at Oak Hill and they will tell you the difference in theory and practical application.

I hope this beter explains Rich's statement.

marcus mcbain
03-02-2003, 10:47 PM
That is pretty impressive information coming from someone that has told me throttle is used to adjust rebound and compression /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif (OK it was actually Scott /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif )

Actaully you are somewhat correct (But only in the most extreme situation). If you soften the spring too much, then the comrpession/rebound would need to be softened up or the corresponding spring/damping rates would be hosed. (This is what would support your "stiffer" scenario) From what I have experienced (personally and from people paying me money to set their suspension up) 1 line (front) and one turn (rear) will not put your settings "out of whack". NOW, if you suspension is hosed up in the first place, I can't do anything for you on that /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

The real important issue here is that I have seen quite a few knuckleheads drop the air pressure 3 or more pounds on the rires, and this AIN'T the hot ticket.

NOW, THEORY and PRACTICE in action - You can go on this BBS or the WERA BBS and see all kinds of opinions on suspension. Everyone has an theory/opinion based off of linkage rates, etc. THE REAL WORLD swallows those opinions like rice in Ethiopia. I have a couple of race winners that I did the "fine" tuning on at Oak Hill and they will tell you the difference in theory and practical application.

I hope this beter explains Rich's statement.

Rich Desmond
03-02-2003, 10:59 PM
Marcus,

I'm not saying changing the pre-load won't help, I've no idea whether it does or not. Physics doesn't lie though, and the reality is that if it does help it's for a different reason than what you're stating.

Rich Desmond
03-02-2003, 10:59 PM
Marcus,

I'm not saying changing the pre-load won't help, I've no idea whether it does or not. Physics doesn't lie though, and the reality is that if it does help it's for a different reason than what you're stating.

marcus mcbain
03-02-2003, 11:56 PM
OK Rich,

First off, I did not imply any specific reason for why I recommend these settings other than they work.

NOW, in regards to your "physics" comments. I am a redneck, so explain the physics to me. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

Here are my redneck physics.

Kinetic Energy is created whenever a "bump" is encountered (Tire/motorcycle rolls over bump).

1) There is a given amount of energy that is absorbed via the tire and suspension as a motorcycle goes around the racetrack and goes over bumps. The tires and suspension (along with geometry) ultimately all work as a balanced mechanism to absorb kinetic energy from a bump and keep the tire contact patch in consistent contract with the race track. (NOTE: In a perfect world, there would be no bumps on tracks, and we would all use those drag race struts instead of shocks /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif )

a) The tire absorbs a proportionately small amount of energy as the carcass "flexes" (On a radial tire) AND transfers energy to the suspension.

b) The suspension absorbs energy as by both the spring and compression/rebound units serve together in different fashions.

1b) The Spring stores energy (it is arguable that the spring dissipates energy)
2b) The rebound and compression units dissipate that energy (from the spring) as oil passes through "valves".
3b) THE SPRING ALSO TRANSFERS ENERGY BACK TO THE TIRE

Overview - Kinetic energy from bumps cause a tendency of tires not wanting to adhere to the asphalt. This creates a bad situation.

Theory – Understanding that the spring stores energy and the rebound and compression units dissipate energy, THEN the spring must not be able to store an unbalanced amount of energy relative to the rebound/compression units and WHAT THE TIRE CAN HANDLE. Both the spring and compression/rebound units must be balanced in their respective setting(s). (NOTE: Changing the spring preload in the amount I suggested should not adversely affect this “ratio” IF the suspension was optimally setup in the first place)

Depending on the conditions (environment if you will) of a racetrack, The spring may need to be able to store less/more energy than other circumstances. In the situation I discussed, I recommended a softer setting for the springs. This (in theory) would allow less potential energy to be “stored” as the spring is now softer. Becuase the spring does not reach higher levels of "stored energy, this would provide a more compliant ride. On a cold surfaced track with tires that are not at the optimal temperature, The following occurs:

1) The actual rubber does not work as well.
2) The carcass may not flex as much.
3) The tires cannot transfer/absorb energy from the track/bump as efficiently as when the track/tires are warm.
4) Having a suspension that is setup for “normal” circumstances will provide a spring setup that is capable of handling more energy than the tire can transfer/absorb.

So anyway, if you take a little of spring out, you will have a more compliant motorcycle in cold weather situations where traction is compromised due to said “cold weather”.

marcus mcbain
03-02-2003, 11:56 PM
OK Rich,

First off, I did not imply any specific reason for why I recommend these settings other than they work.

NOW, in regards to your "physics" comments. I am a redneck, so explain the physics to me. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

Here are my redneck physics.

Kinetic Energy is created whenever a "bump" is encountered (Tire/motorcycle rolls over bump).

1) There is a given amount of energy that is absorbed via the tire and suspension as a motorcycle goes around the racetrack and goes over bumps. The tires and suspension (along with geometry) ultimately all work as a balanced mechanism to absorb kinetic energy from a bump and keep the tire contact patch in consistent contract with the race track. (NOTE: In a perfect world, there would be no bumps on tracks, and we would all use those drag race struts instead of shocks /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif )

a) The tire absorbs a proportionately small amount of energy as the carcass "flexes" (On a radial tire) AND transfers energy to the suspension.

b) The suspension absorbs energy as by both the spring and compression/rebound units serve together in different fashions.

1b) The Spring stores energy (it is arguable that the spring dissipates energy)
2b) The rebound and compression units dissipate that energy (from the spring) as oil passes through "valves".
3b) THE SPRING ALSO TRANSFERS ENERGY BACK TO THE TIRE

Overview - Kinetic energy from bumps cause a tendency of tires not wanting to adhere to the asphalt. This creates a bad situation.

Theory – Understanding that the spring stores energy and the rebound and compression units dissipate energy, THEN the spring must not be able to store an unbalanced amount of energy relative to the rebound/compression units and WHAT THE TIRE CAN HANDLE. Both the spring and compression/rebound units must be balanced in their respective setting(s). (NOTE: Changing the spring preload in the amount I suggested should not adversely affect this “ratio” IF the suspension was optimally setup in the first place)

Depending on the conditions (environment if you will) of a racetrack, The spring may need to be able to store less/more energy than other circumstances. In the situation I discussed, I recommended a softer setting for the springs. This (in theory) would allow less potential energy to be “stored” as the spring is now softer. Becuase the spring does not reach higher levels of "stored energy, this would provide a more compliant ride. On a cold surfaced track with tires that are not at the optimal temperature, The following occurs:

1) The actual rubber does not work as well.
2) The carcass may not flex as much.
3) The tires cannot transfer/absorb energy from the track/bump as efficiently as when the track/tires are warm.
4) Having a suspension that is setup for “normal” circumstances will provide a spring setup that is capable of handling more energy than the tire can transfer/absorb.

So anyway, if you take a little of spring out, you will have a more compliant motorcycle in cold weather situations where traction is compromised due to said “cold weather”.

marcus mcbain
03-03-2003, 12:12 AM
Also Rich,

Renate got a good photo of you and the crew at OH. Make sure you get a copy. I posted High Res shots.

Marcus

marcus mcbain
03-03-2003, 12:12 AM
Also Rich,

Renate got a good photo of you and the crew at OH. Make sure you get a copy. I posted High Res shots.

Marcus

Rich Desmond
03-03-2003, 07:18 PM
Marcus, all that kinematic stuff is mostly correct, but not relevant to the issue. The hard cold fact is that altering the pre-load does not soften or stiffen the spring in the slightest. For example, if you've got the springs pre-loaded 15mm and rider sag is 30mm that means the springs need to be compressed a total of 45mm in order to hold up the weight of the bike and rider. Taking 5mm of pre-load out will just change the rider sag to 35mm, the total compression of the spring (45mm) is the same, and the amount of energy it takes to compress the spring any arbitrary amount is identical. Now, there is a small complication because the trapped air volume above the oil has changed slightly, but if you do the math you'll see that it's a tiny effect. If you don't believe me go ask Max or Paul Thede or Lindeman, I'm sure they'll agree.
I'm not disputing that the changes you're making help, it's just not for the reason you think. Common situation, actually.
And yes, I am a proud graduate of the Scott Levine "Quit whining about the bike and twist the damn throttle." school of road racing. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

PS. Thanks for posting the pics

Rich Desmond
03-03-2003, 07:18 PM
Marcus, all that kinematic stuff is mostly correct, but not relevant to the issue. The hard cold fact is that altering the pre-load does not soften or stiffen the spring in the slightest. For example, if you've got the springs pre-loaded 15mm and rider sag is 30mm that means the springs need to be compressed a total of 45mm in order to hold up the weight of the bike and rider. Taking 5mm of pre-load out will just change the rider sag to 35mm, the total compression of the spring (45mm) is the same, and the amount of energy it takes to compress the spring any arbitrary amount is identical. Now, there is a small complication because the trapped air volume above the oil has changed slightly, but if you do the math you'll see that it's a tiny effect. If you don't believe me go ask Max or Paul Thede or Lindeman, I'm sure they'll agree.
I'm not disputing that the changes you're making help, it's just not for the reason you think. Common situation, actually.
And yes, I am a proud graduate of the Scott Levine "Quit whining about the bike and twist the damn throttle." school of road racing. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

PS. Thanks for posting the pics

marcus mcbain
03-03-2003, 10:03 PM
Hey Rich,

Good enough. I started to write a two page response that talked about hydraulic effect of the forks/springs correlated to the linear action of "straight rate" springs, and the effect of preload but even I know a dead horse when I see one. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

See you all at TWS.

marcus mcbain
03-03-2003, 10:03 PM
Hey Rich,

Good enough. I started to write a two page response that talked about hydraulic effect of the forks/springs correlated to the linear action of "straight rate" springs, and the effect of preload but even I know a dead horse when I see one. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

See you all at TWS.

E. Templet
03-04-2003, 12:58 AM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Marcus McBain:
Hey Rich,

Good enough. I started to write a two page response that talked about hydraulic effect of the forks/springs correlated to the linear action of "straight rate" springs, and the effect of preload but even I know a dead horse when I see one. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

See you all at TWS.</div></div>Get the dead horse off the track!! I'm commin through!!! /ubbthreads/images/%%GRAEMLIN_URL%%/eek.gif

E. Templet
03-04-2003, 12:58 AM
<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">Originally posted by Marcus McBain:
Hey Rich,

Good enough. I started to write a two page response that talked about hydraulic effect of the forks/springs correlated to the linear action of "straight rate" springs, and the effect of preload but even I know a dead horse when I see one. /ubbthreads/images/%%GRAEMLIN_URL%%/laugh.gif

See you all at TWS.</div></div>Get the dead horse off the track!! I'm commin through!!! /ubbthreads/images/%%GRAEMLIN_URL%%/eek.gif

CYCLE 1
03-04-2003, 08:13 PM
If anybody would like to discuss my suspension
theories I would be more than happy to give you
the bottom line in one sentence. These theories have been devoloped over 30 years of racing inferior equipment on really dismal tracks and for two bucks I will include the secret to life!

CYCLE 1
03-04-2003, 08:13 PM
If anybody would like to discuss my suspension
theories I would be more than happy to give you
the bottom line in one sentence. These theories have been devoloped over 30 years of racing inferior equipment on really dismal tracks and for two bucks I will include the secret to life!