MegNeg

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MegNeg
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Posted: Nov 12, 2019 at 4:25 Quote
Second/Third day testing:

My current setup uses 0 tokens, 4 bands. Total rider weight with gear = 172 pounds Shock pressure at 200psi (32% sag)

I'm really enjoying this new setup.


If you're a rider with around my weight, I suggest trying with my current setup first, then either adding tokens and/or removing bands in the MegNeg.

My Trek Remedy has a reported progressivity of 24%, that is, the leverage ratio of the frame's rearward movement. 24% is not linear, but it's not as progressive as some other bikes. I would call the Remedy a mildly progressive bike.

Comparing my bike to some others:

2016 Transition Patrol = 16%
2016 Giant Reign = 23%
2016 Trek Slash = 26%
YT Jeffsy 29er = 49%
SC Nomad 3 = 50%
YT Capra = 75%

Why is progressivity an issue? One of the atrributes about the MegNeg is, it aims to add more progressivity through the shock, so this effect can provide bikes with a more linear leverage ratio some progressiveness, however on bikes with a relatively high progressivity can find the MegNeg to be "too much" progressivity for their liking, almost creating a situation where they can't use a good portion of the available travel.

I'm of the opinion where the YT Capra for example would not be an ideal candidate for the MegNeg, but due to the higher progressivity, it will likely benefit more from a coil shock because the frame is so progressive. You'll gain the suppleness off the top and the bike will take care of most of the bottom out resistance.

My bike seems a lot more active yet very supportive in the mid stroke, so I'm able to carry more speed through techie areas with more confidence and speed, where I had to ease off the speed before. Springing off the berms to jolt ahead past the berms feels easier to do and, at least for my bike, the first 1/3 to 1/2 of the travel almost feels like a coil shock with the progressiveness of an air shock towards 75-80% of the full travel.

Posted: Nov 17, 2019 at 16:00 Quote
XDeltaFactor wrote:
Second/Third day testing:

My current setup uses 0 tokens, 4 bands. Total rider weight with gear = 172 pounds Shock pressure at 200psi (32% sag)

I'm really enjoying this new setup.


If you're a rider with around my weight, I suggest trying with my current setup first, then either adding tokens and/or removing bands in the MegNeg.

My Trek Remedy has a reported progressivity of 24%, that is, the leverage ratio of the frame's rearward movement. 24% is not linear, but it's not as progressive as some other bikes. I would call the Remedy a mildly progressive bike.

Comparing my bike to some others:

2016 Transition Patrol = 16%
2016 Giant Reign = 23%
2016 Trek Slash = 26%
YT Jeffsy 29er = 49%
SC Nomad 3 = 50%
YT Capra = 75%

Why is progressivity an issue? One of the atrributes about the MegNeg is, it aims to add more progressivity through the shock, so this effect can provide bikes with a more linear leverage ratio some progressiveness, however on bikes with a relatively high progressivity can find the MegNeg to be "too much" progressivity for their liking, almost creating a situation where they can't use a good portion of the available travel.

I'm of the opinion where the YT Capra for example would not be an ideal candidate for the MegNeg, but due to the higher progressivity, it will likely benefit more from a coil shock because the frame is so progressive. You'll gain the suppleness off the top and the bike will take care of most of the bottom out resistance.

My bike seems a lot more active yet very supportive in the mid stroke, so I'm able to carry more speed through techie areas with more confidence and speed, where I had to ease off the speed before. Springing off the berms to jolt ahead past the berms feels easier to do and, at least for my bike, the first 1/3 to 1/2 of the travel almost feels like a coil shock with the progressiveness of an air shock towards 75-80% of the full travel.

This is what worries me, I have a 2018 Intense Carbine and its designed around a progressive suspension setup. I'm not sure on % but I wont be taking a jump into a megneg just yet.

Posted: Nov 18, 2019 at 7:46 Quote
The 2018 Intense Carbine has a unique leverage curve.

It's quite linear at the start of the travel going into the mid stroke then ramps up afterwards.

It has a leverage ratio of 2.7:1 and stays that way from 0-60mm of travel, then from 2.6:1 mildly progressive to 2.06:1 from 80-155mm.

Compared to my Remedy, it starts of at a leverage ratio of almost 3:1 then progressively hits around 2.48:1 at 150mm.

What that means is your bike is firmer (due to the ratio) but maintains that firmness throughout up to the mid point then gets slightly firmer towards the end of the stroke. This kind of bike tends to feel a little firm when going slow on the trails but seems to get better as you go faster. The Remedy will be a little more active at slower speeds because it's easier (due to the higher leverage ratio) to get the shock moving but will need the shock to sit a little deeper for support when riding faster.

I'm thinking Intense's goal was to give your bike a more firm-but-linear feel like a coil then give it a mild ramp up towards the end.

What the MegNeg will do is a 3 things.

1. It'll make the initial 0-33% of the stroke seem smoother, making it easier to get the shock moving. So if you're looking for more suppleness over small, spider-web type roots/bumps, it can still provide benefit by giving it a coil-like feel.

2. If you ride a medium-level bumpy section, take a look at how much travel you're using, nothing gnarly with no big hits and see if you're going too deep in the stroke. Also take notice of how much support you're getting in medium terrain. If you have token(s) in the shock right now and feel like you have enough support, the MegNeg can still help giving you a slightly wider range of usable stroke (in the middle range between 20%-80% of your travel) by providing extra "pop" and support because you can still remove token(s) to achieve the same sag point. This can be even more beneficial if you're heavier than me (165 lbs).

Note: Too large a negative pressure volume can work against super light riders for example below 130-140 pounds as they might not have enough force to use all the travel unless they drop from higher heights.

3. If you're a jumper that likes dropping from heights, a larger negative chamber can provide more ramp up towards the end stroke without just relying on tokens.


In summary:

If your shock currently uses 2 or more tokens to achieve a decent ride experience, I'd say the MegNeg is definitely worth trying. What you'll find is that you can use more of the middle portion of your available stroke better without sacrificing the ramp up towards the bottom out all while adding incredibly smooth suppleness off the top for the small stuff.

Posted: Nov 18, 2019 at 8:06 Quote
I'm only 5'6, 165 pounds (172 with gear) and my 2018 Remedy needed 2 tokens before the MegNeg.

Trek's recommended 28% sag didn't work out well when bombing downhill as it acted more like a trail bike (tends to buck around a little too much) so I aimed for 32% sag.

This meant that I needed to let some air out which effectively makes the "air spring" shorter. However at this point I noticed I was riding a little too deep in the travel where I spent a lot of time in the 50-75% range of the stroke, a little too deep and the stroke was roughly 25% of the travel available.

This is like taking your automotive springs, cutting the length some then firming up the spring rate. While it felt stable, it always felt like I was riding a 120mm travel shock, and not 150mm. There were times where I did bottom out the entire stroke without jumps.

I added a token (stock comes with 1) and to achieve the same sag, had to let out more pressure, making the "air spring" shorter. This solved the bottoming out problem, but it made the bike worse in that it felt like it had even less available stroke but it was firm to ride. In effect, this was like using a car equipped with track-level racing suspension on public roads. Way too stiff and bouncy requiring me to up the rebound to keep it all under control, but now losing all the suppleness I enjoyed in the milder stuff.

The MegNeg changed all that. It allowed me to take out all tokens and have the full "air spring" length of the shock meaning there was more available spring to use. With an increased suppleness, dealing with small chatter was almost like my DH bike (Canyon Sender) because the shock moved so easily over smaller stuff, the mid stroke allowed me to sit up higher (on average) on the mid stroke. While before I was sitting between 50-75% of the travel, now the bike was allowing me access to 33-75% of the mid stroke, almost a 100% improvement in range.

So in short, the bike now feels like it has a coil spring from 0-75% of the stroke and an air shock-like progressive ramp up from 75-100% of the stroke.

Posted: Nov 18, 2019 at 14:07 Quote
XDeltaFactor wrote:
The 2018 Intense Carbine has a unique leverage curve.

It's quite linear at the start of the travel going into the mid stroke then ramps up afterwards.

It has a leverage ratio of 2.7:1 and stays that way from 0-60mm of travel, then from 2.6:1 mildly progressive to 2.06:1 from 80-155mm.

Compared to my Remedy, it starts of at a leverage ratio of almost 3:1 then progressively hits around 2.48:1 at 150mm.

What that means is your bike is firmer (due to the ratio) but maintains that firmness throughout up to the mid point then gets slightly firmer towards the end of the stroke. This kind of bike tends to feel a little firm when going slow on the trails but seems to get better as you go faster. The Remedy will be a little more active at slower speeds because it's easier (due to the higher leverage ratio) to get the shock moving but will need the shock to sit a little deeper for support when riding faster.

I'm thinking Intense's goal was to give your bike a more firm-but-linear feel like a coil then give it a mild ramp up towards the end.

What the MegNeg will do is a 3 things.

1. It'll make the initial 0-33% of the stroke seem smoother, making it easier to get the shock moving. So if you're looking for more suppleness over small, spider-web type roots/bumps, it can still provide benefit by giving it a coil-like feel.

2. If you ride a medium-level bumpy section, take a look at how much travel you're using, nothing gnarly with no big hits and see if you're going too deep in the stroke. Also take notice of how much support you're getting in medium terrain. If you have token(s) in the shock right now and feel like you have enough support, the MegNeg can still help giving you a slightly wider range of usable stroke (in the middle range between 20%-80% of your travel) by providing extra "pop" and support because you can still remove token(s) to achieve the same sag point. This can be even more beneficial if you're heavier than me (165 lbs).

Note: Too large a negative pressure volume can work against super light riders for example below 130-140 pounds as they might not have enough force to use all the travel unless they drop from higher heights.

3. If you're a jumper that likes dropping from heights, a larger negative chamber can provide more ramp up towards the end stroke without just relying on tokens.


In summary:

If your shock currently uses 2 or more tokens to achieve a decent ride experience, I'd say the MegNeg is definitely worth trying. What you'll find is that you can use more of the middle portion of your available stroke better without sacrificing the ramp up towards the bottom out all while adding incredibly smooth suppleness off the top for the small stuff.

Thanks for a great insight. I'm about 230 with gear on and have a super deluxe R set at around 276psi with sag just under 30%. Even on medium drops and rough conditions I can barely get more than about 80% to 85% travel on the shaft as per the sag ring. It does feel like it increases a lot in the final 15 to 10% of the travel. I have never come close to bottoming it out yet. It doesnt feel like it needs more small bump compliance but I understand how the megneg does move easier off the top.

I'm not sure how many tokens are in it, I never opened it from new so I'm presuming two standard tokens. I feel if I reduce air pressure to have the ability to use the last 15% of travel makes the bike around 35% sag and it feels to wallowy and sits down too far in the travel.

Posted: Nov 18, 2019 at 18:07 Quote
Great discussion. Thanks XDeltaFactor for opening the topic on kinematics and negative spring effects.

A few clarifications:

I wouldn't say the goal of a larger negative spring is "to add more progressivity through the shock". If the sag point is held constant, then yes, that is one result. The most intuitive and actionable way to describe it is that it smooths out the air spring curve. Have a look at the curve below from Vorsprung; it may not show the MegNeg, but the Corset is very similar:


Notice how abruptly the force builds in the Fox with a small negative spring. If you were to optimize both shocks for your riding, the blue curve would come down, which would create a big dip in the middle. You would probably add some volume reducers to bring up the end stroke progressivity, creating a sharp S-bend curve. The more linear curve with a larger negative spring avoids the force spike at the beginning and the hammock in the middle.

It's important to keep in mind that the sag point shouldn't stay exactly the same. If it did, you would end up with the scenario shown below, in which negative spring length is varied, but the sag point remains the same. The force is too low when the negative spring is short, or vice versa, so a realistic set-up would have less sag with the short negative spring and more sag for the more linear curves.

Effect of negative chamber volume length in the air spring curve. Bigger negative chambers EVOL Debonair Vivid are more sensitive in the first 1 3 of the travel and have more mid stroke support. Thus they need more force to fully to bottom-out.
Effect of negative chamber volume (length) in the air spring curve. Bigger negative chambers (EVOL, Debonair, Vivid) are more sensitive in the first 1/3 of the travel, and have more mid stroke support. Thus, they need more force to fully to bottom-out.

Finally, see below for the Intense Carbine motion ratio curve (motion ratio, in red, is the inverse of leverage ratio). It's a pretty typical curve. The first third is a little flatter than average and it ramps up fairly steeply toward full bump, but it's nothing exceptional.


Posted: Nov 18, 2019 at 18:29 Quote
R-M-R, great points and I agree with you completely.

Posted: Nov 18, 2019 at 18:36 Quote
XDeltaFactor wrote:
R-M-R, great points and I agree with you completely.

But ... this is the internet ... shouldn't we at least insult each other a few times?

Seriously, though, the need for larger negative springs has been one of my (many) soapbox issues for years. Glad to see it's finally getting some attention and people are appreciating the results.

Posted: Nov 18, 2019 at 22:41 Quote
R-M-R wrote:
XDeltaFactor wrote:
R-M-R, great points and I agree with you completely.

But ... this is the internet ... shouldn't we at least insult each other a few times?

Seriously, though, the need for larger negative springs has been one of my (many) soapbox issues for years. Glad to see it's finally getting some attention and people are appreciating the results.

I only insult people face to face, not interested in that sort of stuff behind the internet.

Besides, we're all generally after the same thing, a more enjoyable ride. I agree that larger negative volume chambers (air cans) have been a surprisingly good thing for some riders. It fills in the gap where air pressure, compression/rebound adjustments and tokens alone cannot seem to fix.

Posted: Nov 18, 2019 at 23:03 Quote
XDeltaFactor wrote:
I only insult people face to face, not interested in that sort of stuff behind the internet.

Besides, we're all generally after the same thing, a more enjoyable ride. I agree that larger negative volume chambers (air cans) have been a surprisingly good thing for some riders. It fills in the gap where air pressure, compression/rebound adjustments and tokens alone cannot seem to fix.

A more enjoyable ride is a noble pursuit.

My view is there shouldn't be any situation in which a smaller negative spring produces a better ride. There may be situations where it does, but only as a tool to compensate for wonky kinematics and/or a shock with spring and/or damper design that isn't ideal for a given bike or rider.

Posted: Nov 19, 2019 at 1:54 Quote
Thanks R-M-R for some more great info. As I am on a super deluxe R with no compression adjustment and a MM tune, maybe its better I look into the megneg as it will allow a lot more tuning options with the bands in pos and neg sides.

Posted: Nov 19, 2019 at 2:23 Quote
JNZ wrote:
Thanks R-M-R for some more great info. As I am on a super deluxe R with no compression adjustment and a MM tune, maybe its better I look into the megneg as it will allow a lot more tuning options with the bands in pos and neg sides.

First:

1. Deflate the shock. Does it compress right to the end? Is it possible you actually are getting full travel?
2. Don't expect the shock to get full travel at high speeds. Rapid impacts create a lot of damping force; you're more likely to get full travel on impacts that cause a slower shaft speed, such as g-out compressions.

Once you've confirmed your observations of not getting full travel, let's review:

• You're happy with the initial compliance. This is where the MegNeg excels, but you don't feel a need for that.
• You can't access full travel. The M-M damper tune with your weight and that motion ratio isn't excessive, so it must be excessive support from the spring.
• You're happy with the sag, so you don't want to reduce the pressure.

There's only one thing left: remove the reducers.

Since the MegNeg softens the initial travel, you would need more pressure to maintain your current sag, which will further increase the resistance near bottom-out. The MegNeg is the last thing you need for this specific situation.

Other solutions include:

1. More sag. I don't like telling people to live with a set-up they don't like, but it may be either more sag or you continue to not get full travel. If there aren't any spacers currently installed, then there's nothing more you can do with the current hardware.
2. Coil shock with a bit of preload on the spring. Preload raises your ride height (i.e. less sag) with minimal effect on bottom-out resistance.
3. Bike with less travel. Here's a great discussion of the subject from Steve at Vorsprung:

How Much Travel Do You Really Want?
How Much Travel Do You Really Need?

Posted: Nov 21, 2019 at 19:23 Quote
R-M-R wrote:
JNZ wrote:
Thanks R-M-R for some more great info. As I am on a super deluxe R with no compression adjustment and a MM tune, maybe its better I look into the megneg as it will allow a lot more tuning options with the bands in pos and neg sides.

First:

1. Deflate the shock. Does it compress right to the end? Is it possible you actually are getting full travel?
2. Don't expect the shock to get full travel at high speeds. Rapid impacts create a lot of damping force; you're more likely to get full travel on impacts that cause a slower shaft speed, such as g-out compressions.

Once you've confirmed your observations of not getting full travel, let's review:

• You're happy with the initial compliance. This is where the MegNeg excels, but you don't feel a need for that.
• You can't access full travel. The M-M damper tune with your weight and that motion ratio isn't excessive, so it must be excessive support from the spring.
• You're happy with the sag, so you don't want to reduce the pressure.

There's only one thing left: remove the reducers.

Since the MegNeg softens the initial travel, you would need more pressure to maintain your current sag, which will further increase the resistance near bottom-out. The MegNeg is the last thing you need for this specific situation.

Other solutions include:

1. More sag. I don't like telling people to live with a set-up they don't like, but it may be either more sag or you continue to not get full travel. If there aren't any spacers currently installed, then there's nothing more you can do with the current hardware.
2. Coil shock with a bit of preload on the spring. Preload raises your ride height (i.e. less sag) with minimal effect on bottom-out resistance.
3. Bike with less travel. Here's a great discussion of the subject from Steve at Vorsprung:

How Much Travel Do You Really Want?
How Much Travel Do You Really Need?

I'm sure point 1 will get full travel, I'm off to the skills area at our bike park tomorrow that has progressive drops 1-2-4-6 feet so I'll session them and check how close to full travel I can get. That's not quite a G out landing but closer than repetitive hits.

Once I know a bit more I can look at the next options.

Thanks

Posted: Nov 21, 2019 at 19:40 Quote
JNZ wrote:
Once I know a bit more I can look at the next options.

Thanks

Remove the reducers. That's your first step and it takes only a few minutes. On many bikes, you don't even need to remove the shock - but always depressurize the positive spring first!

Posted: Nov 22, 2019 at 17:29 Quote
Well I can confirm removing the air and cycling the shock down reached full travel. Then I tried twice down a 6 foot drop to heavy rear landing today reached within 1mm of full travel at 267psi. Had no feeling of bottom out though.

Bike felt good all day so I don’t believe introducing a megneg to the situation will make much of an improvement.

Thanks for all your help though R-M-R


 
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