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Formerly PaintPeelinPbody
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Discussion Starter · #1 ·
My bike, a Guerrilla Gravity Trail Pistol (Progressive LR, 120mm travel, 50mm stroke), comes specced from GG with a L/L tune Rockshox Deluxe.

If you're an average weight rider between 140-180lbs, this is probably fine.

Lets say you're not. If your a bigger rider who wants more compression damping, you add some more shims to the compression stack.

Does this change, in effect, replicate the M/L tune from Rockshox?

If you add some more shims to the compression stack and a few to the rebound stack, do you now have a H/M tune?

Or do the type, thickness, etc of shims also impact more specific areas of the tune? I assume IFP pressures factor into this as well.
 

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Can't you just buy the compression assembly you want? Rockshox used to sell 'tune assemblies' for Monarchs but I don't know if they still do for the Deluxe or if they're the same as the Monarch.
 

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Formerly PaintPeelinPbody
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Discussion Starter · #3 ·
I'm not sure. I'm asking this more from a theoretical standpoint.

Like someone says "oh that bike rides great with the L/L tune,but the shock needs more compression damping" if you couldn't go out and get (or replicate by adding shims) a M/L tune.
 

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Can't you just buy the compression assembly you want? Rockshox used to sell 'tune assemblies' for Monarchs but I don't know if they still do for the Deluxe or if they're the same as the Monarch.
Nope RS has gone back to their old ways of not supporting the product after purchase other than simple rebuild kits. No tune options and no small parts (aside from some basic stuff). I have a 2017 Superdeluxe that they changed the rebound tune and added a check valve (that came on the coil models in 2017 but the air I guess got screwed), can't even buy the small parts and instead just expect people to buy an entire new shock for 579.99. With product support like that I think my next won't be rockshox.
 

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So.......I don’t know if there’s a short answer to this, but in general you can change the tune just by adding shims or changing to thicker/thinner (in basic terms). This is the standard method for tuning suspension. BUT a lot of the factory tunes are all over the place and are either not very suitable for a lot of people or hardly have any change between them. Meaning it’s better to have it revalved by someone who can test it properly and know they’re making a difference. Lastly the deluxe doesn’t actually use the shims as it’s main compression valve, so just changing shims won’t do much. It’s actuslly the poppet valve in the shaft controlling most of the damping and you can’t buy replacements for it
 

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To give you an idea, the firmest compression tune Rockshox offered for the Monarch, was softer than the stock Manitou McLeod compression tune.

The L/L and M/M tunes are IMO weird. I don't understand the plan behind their tuning scheme or why large framed bikes are coming with as little damping as they can do!

IFP pressure is about preventing cavitation. It's not really a tuning thing. Less does lower seal friction but it also sucks in more air so you have a shorter service interval.

I'd suggest two things.
1. Go nuts with your own tuning, you have nothing to lose.
2. Start considering a completely different shock.
 

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My bike, a Guerrilla Gravity Trail Pistol (Progressive LR, 120mm travel, 50mm stroke), comes specced from GG with a L/L tune Rockshox Deluxe.

If you're an average weight rider between 140-180lbs, this is probably fine.

Lets say you're not. If your a bigger rider who wants more compression damping, you add some more shims to the compression stack.

Does this change, in effect, replicate the M/L tune from Rockshox?

If you add some more shims to the compression stack and a few to the rebound stack, do you now have a H/M tune?

Or do the type, thickness, etc of shims also impact more specific areas of the tune? I assume IFP pressures factor into this as well.
As Dougal says the IFP pressure does not come into play as far as tuning the damping of a shock. It is there to prevent the oil from foaming under high shaft velocities and oil ripping through the piston in both directions.

In a bit more depth: the thickness and/ or addition of shims will change the forces needed to activate a shim stack (there are a bunch of shims together and bolted in place... in a stack...). However, if you weigh _much more_ than the "average" 180lbs rider then a change in the oil viscosity will be of more benefit. Shims added or subtracted can cover what, about 75 lbs weight range in total, before you run out of space for shims. You're also limited in the number of shims that you can add to any stack! I've tried different oils and prefer the ease of whatev is in the machine because the difference in quality of a hand bled vs. machine bled is important. ( Consistency in performance is my motivator in that regard.)
I am a bigger rider (currently 205 lbs) and usually find that the rebound and compression are on the light side from the factory. I typically add 1 or 2 shims in a 0.006" or 0.0045" to both the compression stack and the rebound stack (respectively). Whether that replicates the M/L or H/L stack I am not sure. It just works for myself and the three other guys who also weigh about the same. The two guys we have in the 275/280 lbs range get two shims in 0.010" and 0.006" _at minimum_ and the last bunch of bikes I did three shims of each for them, no complaints yet! We all ride Fox air shocks, except for me (this year), I'm riding a Fox coil with a change soon to an Ohlins coil that I have lying around. I'll ride that one stock for now and decide if I want to add some shims later after some time in the woods on it.

Side note: "revalving" is a misnomer since that really refers to drilling out piston ports to get more oil or less oil flow.... that hearkens back to the days of yore when pistons were straight drilled through and worked like crap most of the time! Buy a new uncut piston and drill your own ports was the way to got back in the day! But you know... moto / racer guy cross-pollination stuff!!
 

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In a bit more depth: the thickness and/ or addition of shims will change the forces needed to activate a shim stack (there are a bunch of shims together and bolted in place... in a stack...). However, if you weigh _much more_ than the "average" 180lbs rider then a change in the oil viscosity will be of more benefit. Shims added or subtracted can cover what, about 75 lbs weight range in total, before you run out of space for shims. You're also limited in the number of shims that you can add to any stack! I've tried different oils and prefer the ease of whatev is in the machine because the difference in quality of a hand bled vs. machine bled is important. ( Consistency in performance is my motivator in that regard.)
I am a bigger rider (currently 205 lbs) and usually find that the rebound and compression are on the light side from the factory. I typically add 1 or 2 shims in a 0.006" or 0.0045" to both the compression stack and the rebound stack (respectively). Whether that replicates the M/L or H/L stack I am not sure. It just works for myself and the three other guys who also weigh about the same. The two guys we have in the 275/280 lbs range get two shims in 0.010" and 0.006" _at minimum_ and the last bunch of bikes I did three shims of each for them, no complaints yet! We all ride Fox air shocks, except for me (this year), I'm riding a Fox coil with a change soon to an Ohlins coil that I have lying around. I'll ride that one stock for now and decide if I want to add some shims later after some time in the woods on it.

Side note: "revalving" is a misnomer since that really refers to drilling out piston ports to get more oil or less oil flow.... that hearkens back to the days of yore when pistons were straight drilled through and worked like crap most of the time! Buy a new uncut piston and drill your own ports was the way to got back in the day! But you know... moto / racer guy cross-pollination stuff!!
Oil viscosity really affects low speed damping, if you happen to run out of room for shims the next thing to do is increase the clamp shim diameter
 

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Formerly PaintPeelinPbody
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Discussion Starter · #9 ·
However, if you weigh _much more_ than the "average" 180lbs rider then a change in the oil viscosity will be of more benefit. Shims added or subtracted can cover what, about 75 lbs weight range in total, before you run out of space for shims. You're also limited in the number of shims that you can add to any stack! I've tried different oils and prefer the ease of whatev is in the machine because the difference in quality of a hand bled vs. machine bled is important. ( Consistency in performance is my motivator in that regard.)
So would a rider at around say 230-250 need both shims and thicker oil? Or could we get away with thicker oil and a lighter shim stack? Rebleeding to thicker oil sure would be cheap! Could maybe even be done locally.

I am a bigger rider (currently 205 lbs) and usually find that the rebound and compression are on the light side from the factory. I typically add 1 or 2 shims in a 0.006" or 0.0045" to both the compression stack and the rebound stack (respectively). Whether that replicates the M/L or H/L stack I am not sure. It just works for myself and the three other guys who also weigh about the same. The two guys we have in the 275/280 lbs range get two shims in 0.010" and 0.006" _at minimum_ and the last bunch of bikes I did three shims of each for them, no complaints yet!
What shock are you referring to here?

Do guys that big do a combination of more shim and heavier oil, or do they just do the shims and stick with stock oil for ease of machine bleed on your end?
 

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Oil viscosity really affects low speed damping, if you happen to run out of room for shims the next thing to do is increase the clamp shim diameter
Or replace two thinner shims with one thicker. 2x thicker shim is 8x stiffer.

I heard that Deluxe and Monarch have similar shimstacks. There is lots of good information in the Monarch tuning thread.
 
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