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I would say that leverage ratio is the most important factor (if not the only) in determing your compression tune. If the frame is extremely progressive and your leverage ratio falls between two tunes I'd go for the lighter one.
 

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I would say that leverage ratio is the most important factor (if not the only) in determing your compression tune. If the frame is extremely progressive and your leverage ratio falls between two tunes I'd go for the lighter one.
I'm inclined to agree, but it does depend on what you want, and it can be taken too far.

My Marin Alpine Trail has a modestly progressive trunnion linkage, and Marin specc'ed the bike with a Fox Basic DPX2 with a regressive (yes really) compression tune. It felt soggy, wallow-y and "too linear" even at 20% sag and the biggest volume spacer allowed. I was never happy with it. I bought an Elite DPX2, had it tuned by DSD for "light progression" and run it at 22-25% sag. I originally used a big(ish) volume spacer, but was only using 75% of the travel, so I dropped out ALL the volume spacers and upped the rebound a click or two. Super happy with it now. It's -a little- poppy, and fun when hitting features; but still tracks well, and a chest-high huck to flat uses about 95% of the travel.

Modest progression linkage+ light progression tune with a big air can is money for how I ride.
 

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Generally speaking a more progressive frame (vs another of the same average LR) will use a softer tune because the high initial leverage ratio equals a softer spring rate. This needs a lower damping rate to achieve an appropriate damping ratio and a softer spring encourages higher wheel speeds, so overall the damping is doing more “work” than a more linear bike
 

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If all else is held equal does a more progressive (falling leverage ratio) frame need a lighter or heavier compression damping tune?
OP- I just realized i read what I wanted to read in the first post

you ask about progressive rate linkage (more force as you move deeper into travel) and in parentheses clarify (falling rate) but my understanding- and a quick google is that falling rate is less force to move in the deeper parts vs earlier part, which is *regressive linkage, to keep the language the same. progressive linkage = rising rate.
 

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Discussion Starter · #7 ·
OP- I just realized i read what I wanted to read in the first post

you ask about progressive rate linkage (more force as you move deeper into travel) and in parentheses clarify (falling rate) but my understanding- and a quick google is that falling rate is less force to move in the deeper parts vs earlier part, which is *regressive linkage, to keep the language the same. progressive linkage = rising rate.
After looking up the terms what I did mean was "rising rate" as I understand it which I do believe corresponds to a falling leverage ratio but maybe that was a less clear way to put it. I am trying to describe a frame linkage where the wheel has less leverage against the shock towards the bottom of travel and more leverage against the shock at the top. It does look like "rising rate" is the more conventional terminology so maybe I'll edit that for clarity.
 

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Link Ratio
An increase in link ratio decreases the spring and damping force at the wheel. Defining link ratio that way creates confusion.

A better definition of link ratio inverts the relationship to define link ratio as the ratio of shock/wheel motion. Inverting the definition gives the sane result of an increasing link ratio increasing the suspension force at the wheel. Equations defining link ratio (using the sane definition) for the spring and damping force at the wheel are here.

But there's more. Link ratio produces a larger effect on damping than spring force. A progressive link ratio increases damping force when driven deeper in the stroke, which stabilizes the bike when the suspension is recovering from hard hits on a deep stroke. A progressive link ratio also gives a softer spring rate and damping for small motions around race-sag, and that improves ground compliance. Those two effects give a progressive link ratio two benefits: Improved ground compliance and more damping control on deep strokes.

A progressive link ratio has a third benefit. Shim stack controlled damping is inherently digressive. The digressive damping roll-off when processed through a progressive link ratio partially counteracts the damping roll-off to deliver more-or-less constant damping performance over the range of stroke depths.

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However, contrarians argue the opposite. A digressive link ratio makes damping stiffer for small motions around race-sag. That creates a "peddling platform". A digressive link ratio also softens damping on deep strokes, which launches the bike off of jump faces giving the suspension a "playful feel".

Contrarian tribe philosophies are not good for me….
 
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