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Professional Crastinator
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Discussion Starter · #1 ·
I have it in my head that I would like heavier shock oil. But, I know if I do I will have to run both (F and R) rebound dampers wide open fast (or very close to), as opposed to where they are now which is between 1/2 to 1/3 from wide open.

My thinking is that the compression damping will increase (it is not otherwise adjustable on either end of my bike), but I will be able to dial the rebound back to the same as it is now. I am thinking this is the holy grail for my minimally-adjustable stuff.

Yes?

Thanks,
-F
 

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Former Bike Wrench
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Yes, heavier oil will affect compression damping. This can be a useful way to tune a fork that does not have an adjustable compression damper. Just be sure to use the [email protected] degrees C weights and on the weight on the bottle (ie 5w, 10w, etc) as these vary greatly from one manufacturer to another.
 

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EDR
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Oil weight greatly affects damping. Feel free to experiment but like was mentioned compare the cSt @ 40c of what you run now to something you're thinking of trying. The oil "weight" (5w, 10w) is fairly meaningless.
 

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Fleas, yes the fluid viscosity does have an effect. There are however a lot more factors. I'd speculate that for most riders a change from, using the same manufacturer and type fluid, from 5 to 10 would be not impossible but probably not come out and say hi obvious.

If the rider has a very good understanding of the suspension, and understands how to tune it via the clickers, they will likely notice it more easily.

Saying that, the jump from the above mentioned 5 to 10 or in general doubling the Cst, will not directly double the damping force, it will be close in a non shimmed setup that is orifice based.

So, if the Cst were doubled, it is an across the board change, but is most noticed in the freebleed clicker circuits. Stepping further, this change in freebleed flow, equates to the shim stack working sooner on an identical hit.

Suffice to say, that if you are working to cure one portion of the wheels movement, depending upon the design it may suffer in another portion.

Is this for your tandem?

PK
 

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Professional Crastinator
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Discussion Starter · #7 ·
Ha ha! The tandem will be full rigid for a long time.

I have an Iron Horse MkIII with the Rock Shox Monarch 3.1 rear shock and the Rock Shox Recon AM 327 fork. There is no compression damping settings on either (or lockout), just rebound, however they both work just fine and the bike is well-balanced. The DW*Link works great under power, but since I am usually a rigid rider it seems like I am always compensating for what I think is a small short-coming in the suspension to make it work "just right"; that being the compression damping. I set it at 25% sag, it never bottoms harshly, but it never seems like I can lean on it and dig that front wheel into a corner. It just seems to compress forever and never offers a solid platform when I lean on it hard. I think increased compression damping would fix that. I think it would keep me from getting to the bottom of the travel as often, too.

My first thought was to get out my syringe and suck out 1/2 the oil that's in there and replace it with a higher viscosity. This way I probably won't overshoot whatever "sweet spot" I think I can find. I can probably even sorta sneak up on it if I have the patience. Although I'm thinking I won't really know I have it right until I overshoot it and say "that's too much". :D

Thanks,
-F
 

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Fleas said:
Ha ha! The tandem will be full rigid for a long time.

I have an Iron Horse MkIII with the Rock Shox Monarch 3.1 rear shock and the Rock Shox Recon AM 327 fork. There is no compression damping settings on either (or lockout), just rebound, however they both work just fine and the bike is well-balanced. The DW*Link works great under power, but since I am usually a rigid rider it seems like I am always compensating for what I think is a small short-coming in the suspension to make it work "just right"; that being the compression damping. I set it at 25% sag, it never bottoms harshly, but it never seems like I can lean on it and dig that front wheel into a corner. It just seems to compress forever and never offers a solid platform when I lean on it hard. I think increased compression damping would fix that. I think it would keep me from getting to the bottom of the travel as often, too.

My first thought was to get out my syringe and suck out 1/2 the oil that's in there and replace it with a higher viscosity. This way I probably won't overshoot whatever "sweet spot" I think I can find. I can probably even sorta sneak up on it if I have the patience. Although I'm thinking I won't really know I have it right until I overshoot it and say "that's too much". :D

Thanks,
-F
Adding thicker oil in your fork will not change your compression damping at all. Recon 327's do not have a compression circuit, so there is nothing to be effected by the thinker oil. All that it will do is make the rebound more sluggish. The rear shock does have a internal compression circuit though. So adding slightly thicker oil would have an effect on the rear shock, but you need special tools to properly change the oil in your shock.

Im not positive, and I am sure someone will correct me if I am wrong, but you can probably buy a motion control compression damper and install it for relatively cheap. Its probably your best option.
 

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Former Bike Wrench
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mullen119 said:
Adding thicker oil in your fork will not change your compression damping at all. Recon 327's do not have a compression circuit, so there is nothing to be effected by the thinker oil. All that it will do is make the rebound more sluggish. The rear shock does have a internal compression circuit though. So adding slightly thicker oil would have an effect on the rear shock, but you need special tools to properly change the oil in your shock.

Im not positive, and I am sure someone will correct me if I am wrong, but you can probably buy a motion control compression damper and install it for relatively cheap. Its probably your best option.
The 327 does have a compression damper, it is a set orifice size circuit that closes for the lockout. So yes, a thicker oil will have some effect on compression damping. Whether it will solve the problem or not is debatable.

Upgrading to a Motion Control compression damper would be a better option. They run around $50.

We used to tune the old Marzocchi Bomber forks with set orifice damper circuits with oil weight and height so it does make a difference.
 

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Former Bike Wrench
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mullen119 said:
the 327 doesn't have a lock out from what I know.

http://www.togoparts.com/items/view_item.php?iid=4513&did=0&cid=1

I may be wrong, But it seems to be the equivalent of a ora 289 which does not have a compression circuit, Just rebound.
Your right, the 335 is the one with a lock out and compression circuit...my bad

It can be upgraded though and would be a very worthy $50 spent
 
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