# Pro rate spring /pro rate rebound?

#### DEANSFASTWAY

If you have a progressive rate spring would it be beneficial to set up progressive or position sensitive rebound ? Consider this a pro rate spring stores a xcertain energy coefficient at certain lengths if you compress farther the energy increases at a higher rate curve would you think that the rebound force should rise at the same rate, of couse shaft speeds go up and a 2nd stage stack could be tailored to suit the speeds but thats really speed sensitive but Im thinking like true position sensitive? Any thoughts???

#### jmics19067

I think it could be possible to get away with a true position sensitive rebound dampening. In my feeble mind the only force the rebound dampening sees is the coiled spring which would be position sensitive.

never mind as I wrote that I realized it woudl only hold true while in the air. If say on rolling whoops and the wheel is following the ground<as it should> you would have to account for the amount of gravity pulling the bike down against the angle of the back side of the whoop. While rider/bike wieght and gravity would be constant the inertia/angle of the downslope would be changing constantly. Whether or not it is significant compared to the energy stored by the spring I wouldn't know.

How is that for a useless post of me arguing with myself :o

#### terry hay

Member
You are not looking at the whole picture. What happens within the spring is not as important as what occurs at the rear wheel. Any linkage setup has progression engineered into it by altering the leverage. The shock's position is constantly changed by the linkage to create a force curve relative to the rear wheel travel. In order to mimic this occurence progressive springs are used in the PDS setups. Whilst the lean angle of the shock creates a certain amount of progression, it is inadequate and needs to be supplemented with the spring. The damping is and needs to be velocity sensitive as we are trying to control vertical wheel velocity
Originally posted by jmics19067
I think it could be possible to get away with a true position sensitive rebound dampening. In my feeble mind the only force the rebound dampening sees is the coiled spring which would be position sensitive.

never mind as I wrote that I realized it woudl only hold true while in the air. If say on rolling whoops and the wheel is following the ground<as it should> you would have to account for the amount of gravity pulling the bike down against the angle of the back side of the whoop. While rider/bike wieght and gravity would be constant the inertia/angle of the downslope would be changing constantly. Whether or not it is significant compared to the energy stored by the spring I wouldn't know.

How is that for a useless post of me arguing with myself :o

#### DEANSFASTWAY

Yeah Terry we know its velocity sens but Im thinking of a position sensitive possibility tailored to the spring rate ramps.