[jeremy3220]

I just picked up a SC Megatower and it came specced with a RC Super Deluxe Ultimate (air) and I'm having a heck of a time setting this up.

I'm 225 lbs geared up. I set the shock to 255 psi (11 psi over SC's recommendation) to get to 30% sag. I found it was bottoming out a bit too easy. Even just bunny hopping (18-24") would cause it to bottom out. Now, the bike is supposed to be progressive enough to run coil and you can even spec it that way from the factory so I was surprised that I would need volume spacers just to be able to bunny hop it.

So I added two volume spacers, set the sag to 30% (244 psi). On the trail I was still bottoming out on small jumps. I increased the LSC from 4 clicks out to completely closed. This felt noticeably better and improved bottom out resistance somewhat. I'll still have to add more volume spacers to be able to hit everything I normally do at my local trails. However, it feels like there's no support until the last few mm's of the stroke. If my wheels leave the ground, the indicator ring will be within a few mm of the bottom out point.

I still plan to try it with more volume spacers but I find it strange I'm having to stuff this shock with spacers when the bike is made progressive enough for coil. A lot of reviewers were even saying the compression tune felt stiff for them and they ended up running the sag at 32-33% to soften things up. I think either the shock compression is tuned way too light for my weight or there's something wrong with it. I'm trying to figure out if I should a) have it retuned, b) send it back to Rockshox, c) buy a different shock (X2). Thoughts?

 

[LyNx]

Why did you drop the pressure if you were already easily bottoming the shock at 255 PSI? That makes no sense, you just add the volume spacers to try and stop the bottoming out, but run the same pressure you were before :skep:

 

[jeremy3220]

Why did you drop the pressure if you were already easily bottoming the shock at 255 PSI? That makes no sense, you just add the volume spacers to try and stop the bottoming out, but run the same pressure you were before :skep:

To set the sag at 30% which is what SC recommends and everyone runs on these bikes. I'll try running it at 255 next time I go out just to see how it rides.

Edit: just doing some reading in the Bronson V3 thread and it looks like there's quite a few people running down to 25% sag with good results. So I'm going to try just upping the pressure until I get the bottom out resistance I need or it becomes really harsh.

 

[trailbildr]

Those bikes have typically been spec'd with LOW compression tunes because the kinematics are supposed to do the work that a medium compression tune would do.

I'm not a fan of bikes that try to make the rear shock do weird stuff, different compressed and uncompressed chainstay measurements and mandated sag numbers.

Get those volume spacer in there, get the pressure up and ignore their sag recommendo.

mk

 

[jeremy3220]

I think on this bike they use a medium tune. There's a MM320 code written on the shock which I thought was medium rebound, medium compression.

 

[294037]

First thing-forget about sag, it’s a good starting point/indicator but if you’re bottoming the bike out the first thing to do is add more air, simple as that. Sag is too imprecise because it depends on how you are sitting on the bike or it is entirely possible to add 20psi but still make it read 30%.

Second, at your weight you will almost definitely benefit from a firmer tune. Even the medium tunes are usually quite soft so it is likely quite underdamped, but I still think you need more pressure

 

[Dougal]

Use air pressure to set the spring rated based on frequency. Then use volume spacers to change ride-height vs spring rate: https://www.shockcraft.co.nz/technical-support/setup-guide

Do you need more compression damping? Most likely yes. But your problems right now are air spring.

 

[jeremy3220]

Use air pressure to set the spring rated based on frequency. Then use volume spacers to change ride-height vs spring rate: https://www.shockcraft.co.nz/technical-support/setup-guide

Do you need more compression damping? Most likely yes. But your problems right now are air spring.

Your method makes sense to me and I like thinking of setting the spring based on frequency but I also wonder if I'm going to control for ride height (sag) then why not loosely set the ride height and use volume spacers to adjust spring rate? Won't I end up in the same spot? Or is it so you can experience what the changes in ride height makes?

 

[Dougal]

Your method makes sense to me and I like thinking of setting the spring based on frequency but I also wonder if I'm going to control for ride height (sag) then why not loosely set the ride height and use volume spacers to adjust spring rate? Won't I end up in the same spot? Or is it so you can experience what the changes in ride height makes?

That way will also work. But might be more circular to get the same end result.

 

[jeremy3220]

Ok thanks. I'll try upping the pressure first.

 

[Shredur]

I wonder what the Megneg aircain would do. I'm the same weight and considering adding the megneg myself.

 

[jeremy3220]

I wonder what the Megneg aircain would do. I'm the same weight and considering adding the megneg myself.

I wondered about that also. I'm not sure what the downsides are (besides lighter riders not being able to use full travel or heavier riders maxing out the shock pressure).

 

[Shredur]

I wondered about that also. I'm not sure what the downsides are (besides lighter riders not being able to use full travel or heavier riders maxing out the shock pressure).

there is a guy on the pinkbike forums that installed one on his Trek Slash and seemed to think it was a great upgrade that adds suppleness and increased bottom out resistance. I don't think we would have to worry about reaching max psi at our weight.

 

[jeremy3220]

there is a guy on the pinkbike forums that installed one on his Trek Slash and seemed to think it was a great upgrade that adds suppleness and increased bottom out resistance. I don't think we would have to worry about reaching max psi at our weight.

Cool. I've got the "Gnar Dog" token (stupid name) on order. If I can't get the right setup with that and adding pressure then I might try the MegNeg (also kinda dumb name). I really liked how the shock behaved plowing through rock gardens, I just need more support for pumping and landings.

 

[jeremy3220]

Update: I have enough tokens to keep it from bottoming out on everything now. I still feel like I have to either run the pressure stiff and harsh if I want support or soft and wallowy if I want to not get beat up on the chunky stuff. The LSC is at 0 clicks out and the rebound at 1 click. I'm not sure if the MegNeg air sleeve will help or if the shock is just under damped. It seems like if the MegNeg allows the shock to sit deeper in the sag while still offering better midstroke support... that's nice but won't the bike be wallowing on the climbs not having enough LSC? I'm not sure if I'm running the LSC closed to make up for the lack of spring support in the midstroke or if the shock is simply underdamped.

 

[Jesse Hill]

At your weight your probably out of range for what it’s ideally tuned for. The x2 would give you a wider tuning range out of the box than a traditional shim stack shock but you may also look into vorsprung tractive tune. I’m thinking of doing it for mine even though I’m in the right weight range there is still benefits to custom tune and a lot cheaper than an entire shock.

 

[jeremy3220]

At your weight your probably out of range for what it's ideally tuned for. The x2 would give you a wider tuning range out of the box than a traditional shim stack shock but you may also look into vorsprung tractive tune. I'm thinking of doing it for mine even though I'm in the right weight range there is still benefits to custom tune and a lot cheaper than an entire shock.

I think I'm going to swap it with an X2. I've had good luck with that shock on another bike.

 

[294037]

I'm not sure if I'm running the LSC closed to make up for the lack of spring support in the midstroke or if the shock is simply underdamped.

Both

 

[Jesse Hill]

I think I'm going to swap it with an X2. I've had good luck with that shock on another bike.

Probably a good route, I had a ccdb air in the past on another bike and loved that shock and still have a coil on v10. I've been waiting to see if they're ever gonna update the air to more modern air spring design but it's been a while now.