Track 101: Dave Moss on Brake, Gas, Turn - Page 2 - Ducati Supersport 939 Forum
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post #11 of 15 (permalink) Old 07-12-2019, 12:07 AM
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Originally Posted by LowRyter View Post
So this guy doesn't recommend trail braking? It's MSF approach. I didn't catch anything about engine braking but I am guessing he's against it.

I have some questions about the suspension set up too. He seems to go with under inflated tires countered with heavy preload. I suppose that is great for the track (I have no opinion about it) but not for the street I agree with the owner's manual for air pressure (and usually add a couple lbs more) and keep the suspension compliant.
I don’t think you are doing him justice.

Preload is preload. It gives you the right sag, or ride height. Suspension travel to absorb bumps as well as extension to follow depressions and keep the front wheel in contact with the road during acceleration weight transfer.

Damping (rebound) is damping. It needs to be set so the suspension recovers from compression at the correct rate. Too fast and it will carry over the suspension stroke and start back down again. Too slow and it will not be recovered from a previous shock, meaning reduced travel to absorb the next bump. That’s called packing.

The stuff Dave Moss preaches is not proprietary, most suspension experts preach the same lessons.

As for tyre pressure, do you follow the owners manual with hot or cold tyres? When it’s 5C or 35C?

We all know that our tyres have to get to a certain temperature to give us maximum grip. We also know that maximum grip is not necessarily maximum tyre life. We also know that as a tyre warms the internal air pressure goes up.

If you watch the Dave Moss stuff you will realise he uses the increase in tyre pressure to check tyres are getting to the correct temperature range. An increase of 4 psi on the road for a compromise between tyre life and grip, 6 psi for maximum grip on the track, where tyre life is not as important.

If you’re happy to stick with 36 on the road, fine. If you whack extra in for a long run, fine. But have you bothered to understand what is happening, why, and is it really improving anything?
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post #12 of 15 (permalink) Old 07-12-2019, 07:58 AM
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Originally Posted by Ed K View Post
DM also contradicts some of the things said in the “slide” vid, posted earlier.

In the end, imo, there is no one way fits all, “cook book recipe” for performance riding...

These are all tools to have at the ready depending on so many environmental factors that vary between among and street and track riding that the rider needs to assess.

And, from my personal perspective, the most important thing is to maximize enjoyment of the ride, not necessarily speed.

Spot on.

On the street, you've got to make a decision there and then for every bend. You can't stick to one system all the time as there are so many variables.

You may only have a split second to make a decision, and you need to call on experience, feel and talent all in one. Learning various ways to corner and practicing them, is the only way.
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post #13 of 15 (permalink) Old 07-12-2019, 11:07 AM
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Originally Posted by Rhino View Post
Dave Moss knows what he is talking about but in this case it is easy to pic holes with what he is saying.
Agree, plenty of holes. One important one, checking front rebound with the brakes applied.

This video explains how to do it properly. Fast forward to about the 50 second mark to get to the relevant point about the importance of NOT applying the front brake when evaluating rebound speed. You can get a front suspension to return seemingly correct over a wide range of adjustment when the brakes are held on. Without the brakes applied it will respond far more accurately to the actual rebound setting .....

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post #14 of 15 (permalink) Old 07-12-2019, 11:10 AM
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Originally Posted by theresanothersteve View Post
I don’t think you are doing him justice.

Preload is preload. It gives you the right sag, or ride height. Suspension travel to absorb bumps as well as extension to follow depressions and keep the front wheel in contact with the road during acceleration weight transfer.

Damping (rebound) is damping. It needs to be set so the suspension recovers from compression at the correct rate. Too fast and it will carry over the suspension stroke and start back down again. Too slow and it will not be recovered from a previous shock, meaning reduced travel to absorb the next bump. That’s called packing.

The stuff Dave Moss preaches is not proprietary, most suspension experts preach the same lessons.

As for tyre pressure, do you follow the owners manual with hot or cold tyres? When it’s 5C or 35C?

We all know that our tyres have to get to a certain temperature to give us maximum grip. We also know that maximum grip is not necessarily maximum tyre life. We also know that as a tyre warms the internal air pressure goes up.

If you watch the Dave Moss stuff you will realise he uses the increase in tyre pressure to check tyres are getting to the correct temperature range. An increase of 4 psi on the road for a compromise between tyre life and grip, 6 psi for maximum grip on the track, where tyre life is not as important.

If you’re happy to stick with 36 on the road, fine. If you whack extra in for a long run, fine. But have you bothered to understand what is happening, why, and is it really improving anything?
I am keeping 38 lb front and rear on my bike (street riding). Having never been to the track before, I actually increased air pressure when I did a couple of track days (several years ago). Air pressure alone stiffened the suspension and makes for quicker turn in.

I am aware now that most track riders use less air pressure, usually well below the factory recommendation. My issue wasn't to criticize the practice because I really don't know the pro and cons. My point was that if the rider softens the tire pressure that he would likely make it up with a stiffer suspension. Therefore, the suspension and tire settings would likely be different for the street.

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post #15 of 15 (permalink) Old 07-12-2019, 06:50 PM
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Originally Posted by LowRyter View Post
My point was that if the rider softens the tire pressure that he would likely make it up with a stiffer suspension. Therefore, the suspension and tire settings would likely be different for the street.
Be aware, there's another 'hole' in the video when he says 'he'll stiffen up the suspension' by increasing the preload where the riders are experiencing excessive fork travel. That statement is way more incorrect than correct.

Increasing preload will only 'stiffen' the very first 3/4 to 1 inch of suspension travel from fully extended. The point where the front tire is just skimming the surface when the bike is accelerated hard out of a corner. Other than that all it does is raise the front ride height of the bike, which may adversely affect other factors. It'll have more downward travel (at the expense of less upward travel), but it won't be any 'stiffer'.

If the front sag had initially been set for the track, which it was (set smaller than for the road because you don't expect pot holes in a track) then excessive fork travel is likely to be due to (a) underweight springs, (b) inadequate compression damping, or (c) low fork oil height.

While there would be little scope to properly correct some of these possible causes at the track, whether the compression damping was adequate should have been explored before just fudging the sag and lifting the front end. Even if fudging the sag was the only solution on the day, not pointing out this was just a crude fudge and leaving viewers thinking this is possibly the correct way to fix excessive suspension travel is quite misleading, IMO.

P.S. Compression damping can't be evaluated in the pits. Only the rider out on the track can do it (with possibly some guidance).

Last edited by John; 07-12-2019 at 07:00 PM.
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