MegNeg

PB Forum :: SRAM
MegNeg
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Posted: Oct 4, 2020 at 18:29 Quote
HooperAK wrote:
What are thoughts on running megneg on a Jeffsy, I know it's a very progressive frame but I currently have 2 volume spacers in to limit bottom outs. I could probably just remove those to negate the added progressivity from the bigger negative air chamber, and would benefit from better midstroke support and small bump sensitivity, correct?

I'm around 200lb and run about 230psi for 25% sag with 2 tokens.

I’m 200lbs running 3 tokens and 235psi for 25% sag with a stock rct3 on a Kona process 153....megneg install tomorrow and curious what your setup/experience is like with megneg? I am thinking of starting with one token, no bands 285psi.

Posted: Oct 5, 2020 at 11:05 Quote
Lukejacob10 wrote:
HooperAK wrote:
What are thoughts on running megneg on a Jeffsy, I know it's a very progressive frame but I currently have 2 volume spacers in to limit bottom outs. I could probably just remove those to negate the added progressivity from the bigger negative air chamber, and would benefit from better midstroke support and small bump sensitivity, correct?

I'm around 200lb and run about 230psi for 25% sag with 2 tokens.

I’m 200lbs running 3 tokens and 235psi for 25% sag with a stock rct3 on a Kona process 153....megneg install tomorrow and curious what your setup/experience is like with megneg? I am thinking of starting with one token, no bands 285psi.

I really like mine the small bump sensitivity is nice on roots and the shock no longer blows through the midstroke on medium impacts, I think I wound up around 265psi for 25% sag with one band and no tokens, actually feels like it bottoms out a bit too easy so I've thought about removing a band and adding a token but I'm kinda lazy.

Posted: Oct 5, 2020 at 19:40 Quote
HooperAK wrote:
Lukejacob10 wrote:
HooperAK wrote:
What are thoughts on running megneg on a Jeffsy, I know it's a very progressive frame but I currently have 2 volume spacers in to limit bottom outs. I could probably just remove those to negate the added progressivity from the bigger negative air chamber, and would benefit from better midstroke support and small bump sensitivity, correct?

I'm around 200lb and run about 230psi for 25% sag with 2 tokens.

I’m 200lbs running 3 tokens and 235psi for 25% sag with a stock rct3 on a Kona process 153....megneg install tomorrow and curious what your setup/experience is like with megneg? I am thinking of starting with one token, no bands 285psi.

I really like mine the small bump sensitivity is nice on roots and the shock no longer blows through the midstroke on medium impacts, I think I wound up around 265psi for 25% sag with one band and no tokens, actually feels like it bottoms out a bit too easy so I've thought about removing a band and adding a token but I'm kinda lazy.

Cross posting my whole review from the Kona process forum but I went with my initial guess setup and what you’re saying is dead on..I probably just need to drop to 275psi...

First ride on the megneg tonight and it is worth every penny.

Rider info:
32 yo 6’4” 205-210lbs with gear on xl 27.5” cr/dl
First year riding, some dirt bike/street bike experience: I am not the fastest or slowest 3-4’ drop to flats and 15’ long mild tables are the biggest things I’ve done

Super deluxe setup before:
240 psi
Lsc 3 from open
Rebound 4 from open
Sag ~25%
3 tokens

With megneg:
285psi
Lsc 2 from open
Rebound 5-6 from open
Sag ~27.5%
1 token
0 bands

Initial impressions:
-crazy supple off the top: sharp and small (2-3” height) roots and rocks are barely felt and climbing traction is unreal as a result

-midstroke support is insane-possibly a bit too firm on medium chunky stuff with current setup but I am holding momentum in tons of places because of it and having something to push against is really nice in berms, Jump faces etc. hardly ever pedal striking anymore as well (170 fork helped this as well) This was the main area I was having trouble with blowing through travel on all kinds of Smedium drops, jumps, and chunk.

-additional bottom out resistance which was needed as I was using all travel on my mild local trails before and now I’m in the 85-90% realm

-very confidence inspiring: I had 7 PRs in a 7 mile ride so it’s definitely an improvement. I’d say tonight was the first time I’ve ever actually railed a berm- in general I was on rails, the bike finally has the right balance of pop and composure that I couldn’t find before. I was literally seeing a taking lines I haven’t before.

- I would give up a bit of the suppleness off the top for a fractionally less firm midstroke but don’t want to lose any end stroke bottom out resistance- especially since I haven’t been on any bigger hits yet- so next time out I’m going to try 5-10 less psi First which may just be the Goldilocks zone, if not then maybe remove a token. Then add a band, and then try 1 of each to see how it all works and what would be best but I feel I’m only about 10% away from having it completely dialed with the initial hypothesized setup.

Posted: Oct 5, 2020 at 19:47 Quote
Lukejacob10 wrote:
I would give up a bit of the suppleness off the top for a fractionally less firm midstroke but don’t want to lose any end stroke bottom out resistance

Drop the pressure and add a positive reducer (token).

If it's too supple off the top - is there such a thing?! - try adding some LSC before adding a negative reducer (band).

Posted: Oct 5, 2020 at 20:16 Quote
R-M-R wrote:
Lukejacob10 wrote:
I would give up a bit of the suppleness off the top for a fractionally less firm midstroke but don’t want to lose any end stroke bottom out resistance

Drop the pressure and add a positive reducer (token).

If it's too supple off the top - is there such a thing?! - try adding some LSC before adding a negative reducer (band).

Next ride I’m for sure dropping pressure then if it’s not just right I’ll try adding a little lsc for shots and giggles ...and if I start to bottom I’ll add the second token... I’m definitely not saying it’s TOO supple off the top- more so that in a world of trade offs that’s the one I am willing to make...I think the real problem is now I can see how the lyric would improve with a larger negative chamber! Haha

Posted: Oct 5, 2020 at 20:22 Quote
Lukejacob10 wrote:
I think the real problem is now I can see how the lyric would improve with a larger negative chamber! Haha

Already has one of the largest on the market, but I agree, it's incredible it's taken the industry decades to fix the tiny negative springs that were ruining air spring performance for anything other than XC racing.

As much as I'm a fan of coils, the emerging crop of large negative springs, multi-chamber positive springs, and air dampers (ex. Ramp Control, Neopos) are bridging the gap and making the extra weight of coil springs difficult to justify.

Posted: Oct 6, 2020 at 20:29 Quote
R-M-R wrote:
Lukejacob10 wrote:
I think the real problem is now I can see how the lyric would improve with a larger negative chamber! Haha

Already has one of the largest on the market, but I agree, it's incredible it's taken the industry decades to fix the tiny negative springs that were ruining air spring performance for anything other than XC racing.

As much as I'm a fan of coils, the emerging crop of large negative springs, multi-chamber positive springs, and air dampers (ex. Ramp Control, Neopos) are bridging the gap and making the extra weight of coil springs difficult to justify.

Not to mention the tune-ability and price point of is killer compared to coils...can’t speak to pedaling platform as I haven’t ridden a coil but from what I understand air wins that as well.

Posted: Oct 6, 2020 at 20:35 Quote
Ease of tuning (for the consumer) and ease of spec (for the vendor) are huge wins for air springs.

Pedaling performance is a complex issue and there's a case to be made for coils being more efficient, so let's say the jury is out on that issue.

Coils don't have to be more expensive than air springs. When the same damper is available with either spring type, the price is usually the same or very similar.

Posted: Oct 18, 2020 at 22:57 Quote
I have a new V2 Sentinel and would like to know whether a MegNeg will give me what I’m looking for. I’m used to really active suspension (came from a 2017 stumpy) so the sentinel seems to feel a bit harsh to me, though it is extremely poppy, which I like. I have been experimenting with +tokens and pressure and so far it feels like the lower the pressure I run the better it feels. However, to keep from bottoming out I need to add more and more tokens, currently running two +tokens. I have also noticed slightly more pedal bob at lower pressures (about 155psi for my 185lbs).

My thought is that megneg will get me the suppleness I enjoy from low pressures and increased sag, but keep the rest of the spring curve more supportive to avoid bobbing and bottoming out. I’d like a bit more braking traction from the rear, and less harshness over faster sections with small bumps like 1-2” roots.

Would the megneg help me to find the feeling I’m looking for?

Posted: Oct 19, 2020 at 3:36 Quote
scottziesman,

Interesting situation. Sounds like some of what you're feeling can be attributed to the spring and some may be the damper. Overall, yes, the MegNeg will help, but it may not solve everything.

"Harshness" can come from many factors. It's more often the damper than the spring. Your first step could be to reduce the low-speed compression damping and, if possible, high-speed compression damping. The latter may reduce resistance to bottoming out, though. You should also test faster rebound to ensure it's not packing down; this may also improve braking traction.

Large negative springs, such as the MegNeg make the spring curve more linear. This should be the default for air springs, and the S-shaped curve caused by a smaller negative spring should be the tuning option for bikes with weird kinematics. The MegNeg will improve the performance of most bikes.

One way to think of the MegNeg's effects is that it reduces support in the first roughly third of the travel. This could allow you to keep the rest of the travel exactly as-is or, more applicable to you, you could raise the pressure to raise the support in the middle and end thirds without making the first third too supportive.

You're correct the MegNeg can give you the feel of running more sag with more support later in the travel. You would probably like the feel with more air pressure and fewer positive spring reducers (tokens). It won't do much for the bobbing, though, since the support will be similar in the pedaling zone, from the sag point to around 50%*, and it may reduce the "pop".


* This may sound contrary to what you see on charts of MegNeg vs. standard air spring curves, but those usually show the curves at constant pressure or constant sag. A typical set-up is somewhere between those two, splitting the difference and making the MegNeg curve a little lower at sag and a little higher at 50%.

Posted: Oct 19, 2020 at 14:02 Quote
Ya. It sounds like it’s worth a try. Pretty minimal cost for way more tuning. My reasoning is that the bike seems to feel good with low pressures, faster rebound, and about 32-35% sag. However, in order to get the nice feeling, I’m running quite low pressures and filling up on volume spacers. If I can get the same feeling with higher pressure and less volume spacers, I feel like I will be better off.

I currently have no LSC in the rear, and if the megneg makes it too active I feel like I could add some lsc to calm down the rear end.

Posted: Oct 19, 2020 at 15:31 Quote
Yep, sounds like you're a good candidate.

When people question why they should use a larger negative spring, I find it's helpful to flip the situation: imagine a large negative spring is the default and we're discussing when to use the standard spring. It's difficult to make a case for a rapid onset of support in the first ~20% of the travel and a soft "hammock" in the middle.


scottziesman wrote:
I currently have no LSC in the rear

Well, you're using the minimum LSC available on your shock's tune, which isn't zero. You could change to a lighter tune to get back into the middle of the adjustment range.

Posted: Oct 20, 2020 at 7:24 Quote
TLDR: Love the feel of the MegNeg with 0 tokens 2 bands, but am looking for a bit more bottom-out resistance. Should my first change be to 1 band + more pressure or add a positive token?

My riding is a mix of XC trails with a healthy side of dirt jumps. The largest drop I do regularly is 4ft and that's where I'm finding myself bottoming out at least half the time.

Context:
2021 Marin Hawk Hill 27.5
Deluxe Select R (This shock's rebound range is 9 clicks and I've been running it 6 clicks from open).

Prior to the MegNeg, my sweet spot was 173psi with 2.5 positive tokens. 3 Tokens was too much and I never used all the travel, even on lift service days.

My initial setup with the MegNeg is 0 positive tokens and 2 bands @ 227psi. For some reason almost 40% more pressure was needed to achieve the same 30% sag. I'm loving the suppleness off the top and appreciate the slightly firmer mid-stroke but don't want to be bottoming out on a typical ride.

Posted: Oct 20, 2020 at 8:03 Quote
ThermalAttorney wrote:
TLDR: Love the feel of the MegNeg with 0 tokens 2 bands, but am looking for a bit more bottom-out resistance. Should my first change be to 1 band + more pressure or add a positive token?

My riding is a mix of XC trails with a healthy side of dirt jumps. The largest drop I do regularly is 4ft and that's where I'm finding myself bottoming out at least half the time.

Context:
2021 Marin Hawk Hill 27.5
Deluxe Select R (This shock's rebound range is 9 clicks and I've been running it 6 clicks from open).

Prior to the MegNeg, my sweet spot was 173psi with 2.5 positive tokens. 3 Tokens was too much and I never used all the travel, even on lift service days.

My initial setup with the MegNeg is 0 positive tokens and 2 bands @ 227psi. For some reason almost 40% more pressure was needed to achieve the same 30% sag. I'm loving the suppleness off the top and appreciate the slightly firmer mid-stroke but don't want to be bottoming out on a typical ride.

That is the question isn't it. I just switched to a float x2, but with the megneg i had, I think i would have been better off running 4 bands and one token (even with 4 bands, that's still something like a 70-80% larger negative chamber than stock was) with less pressure. It seemed to me that sometimes the negative chamber was so powerful that it made the first 30% of the stroke almost "dead" and you had to run so much air pressure that it started to become ridiculous.

Posted: Oct 20, 2020 at 10:44 Quote
What are you guys doing for lower shock mounting hardware when install the SuperDeluxe? Transition says it's a 25x8mm, and the closest RockShox kit available is 25.4x8mm. Does the stock Fox DPX2 hardware work without issues? File down the 25.4mm RS kit to fit?

Edit: thought I was searching/posting the Transition Forum. This is for a '19 Patrol.


 
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