Tread Envy | Code Break

[ktk_ace]

http://www.motorcyclistonline.com/features/columns/tread_envy_code_break/

[YellowDuck]

Great article that no doubt will be of interest to a lot of street riders. I do take exception to this though:

 

One tip is to soften the suspension, especially at the rear, so you aren't feeling every distracting bump and ripple in the pavement. That feedback alone can make a rider wary of approaching traction—and lean—limits. A plush 30–40mm of sag when you are seated on the bike is a good place to start.

While I agree that 30-40 mm is a reasonable sag setting for the street, removing preload to add sag is not going to "soften the suspension". It is just going to change the position in the stroke where the suspension is riding, and reduce the chance of topping it out on negative (extension) travel - spring compression will be the same. In fact, on most (practically all) bikes adding rear sag will make the rear suspension a bit firmer because of the progressive linkage - the mechanical advantage that the shock has over the swingarm increases as the swingarm rises, which it does if you add sag.

 

Sorry, pet peeve of mine. Otherwise great article.

[faffi]

If you happen to own an old style bike with twin shocks and progressive springs, you will (I believe) actually stiffen the action with extra preload by more or less eliminating the softer part of the spring from coming into action.

[YellowDuck]

If you happen to own an old style bike with twin shocks and progressive springs, you will (I believe) actually stiffen the action with extra preload by more or less eliminating the softer part of the spring from coming into action.

 

Not unless you are riding around with the suspension topped out (which you had better not be).

 

As long as it is not topped out with you on board, the spring compression will be the same - however much it takes to support your weight and the bike's weight. The fact that you achieved some of that total compression with preload and the suspension is therefore more extended in use does not affect the additional suspension action per unit force.

 

The exception to this the case of (usually) forks with really long topout springs. If you add so much preload that you are riding around with the topout springs engaged then yes, the suspension will be stiffer at the top of the stroke. But that's an exception, not the rule.

 

Eirik, I know you like technical stuff, so I am betting you will enjoy this site. Best series of technical articles on motorcycle suspension I have ever seen:

 

http://www.promecha.com.au/springs_basics.htm

 

There are three technical articles on springs, and then it goes on to linkages and leverage.

[Lnewqban]

Please, explain this fragment:

 

"Then work on cornering grip, not drive grip."

[faffi]

 

If you happen to own an old style bike with twin shocks and progressive springs, you will (I believe) actually stiffen the action with extra preload by more or less eliminating the softer part of the spring from coming into action.

 

Not unless you are riding around with the suspension topped out (which you had better not be).

 

As long as it is not topped out with you on board, the spring compression will be the same - however much it takes to support your weight and the bike's weight. The fact that you achieved some of that total compression with preload and the suspension is therefore more extended in use does not affect the additional suspension action per unit force.

 

The exception to this the case of (usually) forks with really long topout springs. If you add so much preload that you are riding around with the topout springs engaged then yes, the suspension will be stiffer at the top of the stroke. But that's an exception, not the rule.

 

Eirik, I know you like technical stuff, so I am betting you will enjoy this site. Best series of technical articles on motorcycle suspension I have ever seen:

 

http://www.promecha.com.au/springs_basics.htm

 

There are three technical articles on springs, and then it goes on to linkages and leverage.

 

Thanks for the link.

 

About preload - even if the suspension isn't topped out, you will still vary the amount of negative travel. You will notice a difference between 1 cm and 7 cm of negative travel when it comes to absorbing dips. A huge difference.

[YellowDuck]

 

 

If you happen to own an old style bike with twin shocks and progressive springs, you will (I believe) actually stiffen the action with extra preload by more or less eliminating the softer part of the spring from coming into action.

 

Not unless you are riding around with the suspension topped out (which you had better not be).

 

As long as it is not topped out with you on board, the spring compression will be the same - however much it takes to support your weight and the bike's weight. The fact that you achieved some of that total compression with preload and the suspension is therefore more extended in use does not affect the additional suspension action per unit force.

 

The exception to this the case of (usually) forks with really long topout springs. If you add so much preload that you are riding around with the topout springs engaged then yes, the suspension will be stiffer at the top of the stroke. But that's an exception, not the rule.

 

Eirik, I know you like technical stuff, so I am betting you will enjoy this site. Best series of technical articles on motorcycle suspension I have ever seen:

 

http://www.promecha.com.au/springs_basics.htm

 

There are three technical articles on springs, and then it goes on to linkages and leverage.

 

Thanks for the link.

 

About preload - even if the suspension isn't topped out, you will still vary the amount of negative travel. You will notice a difference between 1 cm and 7 cm of negative travel when it comes to absorbing dips. A huge difference.

 

 

Agreed. Not topping out the suspension hard in big dips will make quite a difference in how it feels. 7 cm is not a realistic number though - that would certainly lead to bottoming under braking or even hard cornering, if you could even achieve that much sag.

[ktk_ace]

 

 

 

If you happen to own an old style bike with twin shocks and progressive springs, you will (I believe) actually stiffen the action with extra preload by more or less eliminating the softer part of the spring from coming into action.

 

Not unless you are riding around with the suspension topped out (which you had better not be).

 

As long as it is not topped out with you on board, the spring compression will be the same - however much it takes to support your weight and the bike's weight. The fact that you achieved some of that total compression with preload and the suspension is therefore more extended in use does not affect the additional suspension action per unit force.

 

The exception to this the case of (usually) forks with really long topout springs. If you add so much preload that you are riding around with the topout springs engaged then yes, the suspension will be stiffer at the top of the stroke. But that's an exception, not the rule.

 

Eirik, I know you like technical stuff, so I am betting you will enjoy this site. Best series of technical articles on motorcycle suspension I have ever seen:

 

http://www.promecha.com.au/springs_basics.htm

 

There are three technical articles on springs, and then it goes on to linkages and leverage.

 

Thanks for the link.

 

About preload - even if the suspension isn't topped out, you will still vary the amount of negative travel. You will notice a difference between 1 cm and 7 cm of negative travel when it comes to absorbing dips. A huge difference.

 

 

Agreed. Not topping out the suspension hard in big dips will make quite a difference in how it feels. 7 cm is not a realistic number though - that would certainly lead to bottoming under braking or even hard cornering, if you could even achieve that much sag.

 

 

IMHO ... the type of springs (straight/double/triple/progressive rate) also affects how dips and bumps are felt