wallow is boat-like handling
rigel said:
I've read in some posts that certain suspension forks and designs "wallow" in their travel.
What does this mean?
There is a full suspension handling balance, between the front and rear, through a range from allowing too much irregular wallow like a boat rocks about in bumpy water or being too firm, harsh, and choppy handling. It's tunable by adjusting springs and damping. There is almost always much more weight on the rear suspension, except during hard braking, so the majority of the adjustment for stable handling is tunable at the rear suspension.
Before platform damping, firming up rebound damping to tune out wallow was the common way, particularly with rebound-only adjustable shocks. Any firming of compression adjustment tends to result in harsher bump compliance. Before travel-speed-reactive platform damping, long travel bikes with their softer spring rates, or shorter travel bikes that squat and bob a lot and steep seat and steering angles placing the rider up high, tended to need firmer rebound damping and over firm springs that reduced usable travel to tame the boat like wallowy handling to be more stable and predictable in bumpy conditions. But firmer rebound damping packs down the spring (not allowing full rebound recovery) and becomes increasingly firmer as speeds increase over repeated bumps.
Platform damping firms up very slow speed compression damping which is the only travel speed where wallowing boat like handling needs a firming reaction to stabilize handling. Bump hits are sharp and cause fast shock travel and the firmer very slow speed platform damping blows open the damper valve for softer and freer acting medium and higher speed main circuit damping. So springs and rebound damping can be tuned for higher speed uses, while the slower speeds are stabilized by the platform damping reaction.
Platform shocks produce add-on reactive suspension when the built in suspension path geometry is not advanced enough in design to produce stable pedaling and handling without wallow or over sprung to be firm and choppy. Long travel bikes have enough leverage and soft rate springs where the platform reaction is a great benefit without reducing any noticeable low-speed small bump compliance. Shorter travel suspension combined with platform reactive damping produces some more noticeable loss in smaller bump compliance and choppier handling at lower speeds except when the rear suspension is fully weighted during slow climbing or hard acceleration.
The very few advanced stable-platform path geometry designs only firm suspension to be more stable when tensioned by rider modulated pedaling or braking in sync with rider positioning and effort. They are more completely free of unnecessary suspension reactive input, having freer acting damping at all speeds, more "fully active". The advanced designs are subtly smoother and better handling over a greater range of speeds, without the compromises of platform reactive damping. Or if platform damping is used on a more advanced design the reactive damping does not need to be adjusted as firm for stability without handling wallow.
- ray