Why re-valve a shock?
- From: TRS Media | Published: January 26th, 2007 - 11:10 pm
The most recent example of this situation comes from a rider testing last weekend at Jennings.
We had just put a new Ohlins set-up on the bike. After listening to how the rider’s weekend went we got the impression that the forks were okay but the rear end of the motorcycle was not quite right. He indicated that he was having some difficulty finishing the corners and that under heavy breaking the back end was wandering. He also said that with the pre-load out of the spring on the shock it improved the grip out of the corner but made the entry worse.
When we did the shock originally at the rider’s request we built a softer or smoother set-up (a personal preference). According to his weight and experience we put a softer (compression side) valve set up and a spring on the heavier side for his weight, adjusters set up neutral. While he liked the handling overall, with the adjustments available he could only make the corner entry better by losing ground on the exit or vise-versa. He couldn’t seem to find the middle ground. This is where most people make the big mistake. They figure “that’s it” and start to ‘ride around’ the problem.
The correct thing to do is re-vale the shock and try another spring. We will put another valve stack in – one that tests with similar characteristics only stiffer, so we know exactly what it will change. At the same time we will drop him down on the spring. By reversing the damping condition he still should have a ‘softer ride’ however, the shock will become ‘slower.’ This should help by preventing the rear end of the bike from collapsing going into the corner (no more hopping). At the same time the softer spring should allow the tire to grip on exit without compromising the geometry, allowing it to finish the corner. Problem fixed!
Actually, if it was that easy the AMA Pro teams would send the suspension guys home after spring testing. The truth is the rider is going to have to go back out there and test it again. We have the data and the change will make it better, but then he gets faster, the tire company comes out with a new tire and we start all over again. This is where relationships come into play. Because we now know what works best for ‘him’ we will be able to keep the chassis moving in a manner he likes, even as everything around him changes.
We’ll follow up with a discussion about forks soon.
