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Discussion Starter · #1 ·
So I've noticed some bikes feel plusher and more active than others...but leaving out shock tunes for a moment, what exactly contributes to a bike being more active and plush? People say antisquat improves pedalling efficiency but can detract from bump absorption. But the thing is once you are going at decent speed and not pedalling, the hub freewheel should be rotating too fast for antisquat to be an issue, so other than rearward axle paths and all that malarky, what actually makes one bikes suspension design feel more active than anothers when coasting downhill.. Shouldn't in theory a VPP, Horst, Switch etc, with the same leverage ratio, amount of rearward axle path and shock tune all feel exactly the same once going fast enough that antisquat is not interacting with the system, or is there more to it than that? Always wondered about this as I'm not particularly fussed about bikes that pedal well, if I ever found one that pedalled so bad I hated it, I would just fit a shock with climb lever like I currently have but never use.

I guess I'm wondering if a lot of reviews too are more based on shock tunes than the actual kinematics of the bike...for example the Specialized Enduro gets rave reviews for descending, yet on paper, it has huge levels of antisquat, average rearward axle path, air shock and a typical level of progressivity these days,...so what exactly about it is making it soak everything up more than a lot of it's competitors, FSR or what?
 

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Mostly leverage ratio, and change in ratio. A high initial ratio will feel plush as it overcomes the spring and friction easily.
But it is the combination of all those metrics that can distinguish two bikes from each other, and even curves that look very similar can have a very different rate of change as it moves through the stroke. A sudden change in spring force will feel harsh even if the instantaneous forces aren’t huge. And while anti squat or pedal kick back might look fine at sag, if the curve is too steep it will have a higher likelihood of pedal feedback

and never rule out friction, the linkage and eyelet bushings might feel fine in the stand but once they are under load it’s a different story!
 

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It's definitely a combination of factors. Sometimes how a bike looks like it should ride on paper is very different from how it actually rides in real life. You can also change the feel of a bike quite a bit by changing suspension components. I did this with my Bronson v2 by adding a DHX2 shock, which tremendously changed the ride from what it was like with an air shock.

As for the enduro, from what I've read, Specialized was experimenting with the linkage design on their downhill bike when they stumbled upon a really good design that increases pedaling performance while preserving downhill performance. They are now in the process of trickling that design down to their whole line of MTBs.
 

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Discussion Starter · #4 ·
Is that really all it is then, just leverage ratio and shape of the curve? I thought there might be something more complex going on, as a lot of basic 4 bar designs I have tried although feel mushy when pedalling, also seem more active when coasting too....perhaps as you say the less complex design just running on a few bearings creates a noticeable reduction in loaded friction.
Another thing is do air shocks for a given frame generally feel softer through square edge hits etc due to the reduced midstroke support of a coil? I remember when I fitted a coil to my previous SB6, the small bump and traction was night and day better, but I felt I may have been feeling more through larger hits....though this was a used DHX5.0 shock I just fitted to try it...I played around with shimstacks not fully knowing what I was doing to try and reduce the damping, so maybe I removed too much damping.

Also chainstay length, I believe longer stays create a better feeling rear end as your weight is more centralized on the bike, how much truth is there to that or can that mitigated by changing the tune front and rear of your bike?
 

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LC, axle path and shock type seem to make the biggest difference to me, with the caveat that anti squat significantly more than 100% can start to feel janky, but few bikes increase though the travel or are that high (well over) deep in the travel. Axle path is a double edged sword. Disadvantages and advantages to each setup, maybe with an edge towards vertical/rearward for a DH-only bike. But apart from the other suspension disadvantages, that makes it harder to wheelie and manual.
 
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Discussion Starter · #6 ·
I can definitely see why a rearward axle path could help, but I've tried a few cheaper alloy 4 bar bikes and tend to have been very soft, mushy, but create huge traction and suppleness, and from what I k ow they don't have largely rearward axle paths. By LC do you mean low speed compression? I'm just trying to determine how much you could theoretically shock tune a bike to feel the same as another bike with different kinematics. I don't expect any normal bike to roll over stuff as well as the new Norco Range or Dreadnought as their axle paths are magnitudes more rearward than other enduros on the market.
 

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You can achieve something like that with high and low speed compression. By dialing down the low speed compression and dialing up the high speed compression, you get a more progressive, supple feel off the top with a more bottomless stroke. Conversely, if you increase the low speed compression you get a better, less mushy pedaling platform at the expense of small bump compliance.
 

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Discussion Starter · #8 ·
Well yea, that's exactly what I got Darren to do with my 11.6, he fitted a 2 stage stack massively improving small bump as my Sb165 is already supportive and pedal efficient enough and it's good. But what I don't get is why I had to go to the extent of fitting an expensive coil and getting a revalve to feel as supple as cheaper alloy 4 bar bikes that are running non piggyback mid range air shocks? My bike is 28% progressive and I imagine more progressive than those cheaper bikes as it was designed around a coil...so given the progressivity is not an issue,and antisquat becomes a non factor when coasting faster than the hub can engage, why would I need to go to that extent to achieve the same suppleness and activeness of a less progressive bike running an air shock...this is what I don't get, and wondered if there was more complex things involved.
 

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I'm not an engineer but it seems like you're isolating one or two factors when there are many more to consider. The fact that your sb165 is 28% progressive doesn't tell you much in isolation. What about wheel path and wheel rate? Also, antisquat is a factor when your suspension moves, because when you take a big hit, the suspension moves, the chain grows, and it can engage the free hub. You are also rarely just coasting while riding. Braking forces and rider input play a role. Frame design also plays a role - chainstay length, front-center length, and total wheelbase can all contribute to how a suspension feels. What about front suspension tune? That can play a role as well.

A mountain bike is a complex system and it's not always easy to get the measure of one by looking at the sum of its parts. For example, you can have two horst-link designs that ride very differently.
 

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Discussion Starter · #10 ·
So yea, the other bikes were much shorter with longer stays and steeper headtubes.. when you say wheel rate what do you mean, isn't that all going to be detetmined/offset by spring rate. For what it's worth the other bikes were lower travel and also running less sag % so in theory I would expect the ride to feel firmer but it didn't... Guess I'm fairly happy with the bike now, but just wondering what to look out for in the future when purchasing my next bike...there isn't really anywherw local that does demo days close to me so I can only really ever go off reviews or looking at stuff on the Linkage design blog etc
 

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Were they all running the same shocks? The component spec can often have more of an impact on ride feel than kinematics. It's pretty difficult to just go by the numbers. The only real way to tell how a bike will ride is to demo it or hear about it from people who have ridden it.

Another issue I've had is I demo a bike, think it's one thing, but then after buying it and putting a few thousand miles on it, some things I don't like start to show. I've gone through four different rear shocks and two forks on my Bronson v2 trying to get the feel I was looking for. I finally got to it after much experimentation. Or maybe I just got used to it, idk. Maybe we should stop obsessing over this sh!t and just go ride the bikes.
 

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Is that really all it is then, just leverage ratio and shape of the curve? I thought there might be something more complex going on, as a lot of basic 4 bar designs I have tried although feel mushy when pedalling, also seem more active when coasting too....perhaps as you say the less complex design just running on a few bearings creates a noticeable reduction in loaded friction.
Another thing is do air shocks for a given frame generally feel softer through square edge hits etc due to the reduced midstroke support of a coil? I remember when I fitted a coil to my previous SB6, the small bump and traction was night and day better, but I felt I may have been feeling more through larger hits....though this was a used DHX5.0 shock I just fitted to try it...I played around with shimstacks not fully knowing what I was doing to try and reduce the damping, so maybe I removed too much damping.

Also chainstay length, I believe longer stays create a better feeling rear end as your weight is more centralized on the bike, how much truth is there to that or can that mitigated by changing the tune front and rear of your bike?
When you say a mushy bike also feels active when coasting, what makes you think it wouldn't? Anti-squat isn't just the response to pedalling, it's the response to weight shift due to acceleration so still exists even without a chain. The value will change as the chain torque is a significant factor.

not to be a pedant but 4-bar used to specially mean Horst link/FSR bikes, is that what you are talking about? Or do you mean any generic 4-bar arrangement? FSR bikes did used to have pretty low anti squat numbers as they wanted less brake influence on the suspension.

As for air feeling softer - it's never that simple, if it's soft through the mid stroke it will probably feel harsher as it blows through too fast or a spike from the initial friction/spring rate. Or it might feel good, if you have an air shock with variable spring rate combined with a leverage curve of changing rate it will be very dependent on the exact sag you are using.

tuning shocks to make differentframes feel similar - technically no you can't make it the same, as while you might make the wheel spring rates similar the damping will behave very differently and you can't match them up. Damping is obviously speed dependent and springs are position dependent. If you use a
More digressive spring rate on a progressive frame for example to get a linear feel, it will have lower shaft speeds at the damper than a straight linear bike, so not enough damping force will be generated. A progressive bike with a soft initial wheel travel will encourage faster shaft speeds and create enough damping to be under control. Hope that makes sense. ?
 

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Discussion Starter · #13 ·
Yea that makes sense. In terms of the antisquat still affecting the bike without a chain due to acceleration I guess that is the missing piece of the puzzle I was trying to figure out that must be partly responsible for the difference in activeness, I didn't really know that was a thing, I've only really ever seen antisquat talked about in relation to pivot placement and it's affect on the chain and kick back etc..

Yea I mean 4 bars like the older Cube Stereo, Specialized FSR etc... They tend to respond very well to bumps but have really porr pedal efficiency. I was thinking at coasting speeds without the hub engaged all suspension designs regardless of antisquat should feel the same aside from obviously the leverage ratio.

So in terms of suspension design, if one is just looking for a winch and plummet bike, with no care for pedal efficiency, what would be the best option, what would work best on a downhill specific bike for example in your experience?

I bought my SB165 on a bit of an impulse, I saw a cracking deal on the frame and thought with it's coil shock, dh bike geo and freeride intentions that it woukd be super active and planted....before that I was looking at the Zerode, Geometron and Propain Spindrift, I'm wondering if one of those would have been a better option. Don't get me wrong my bike isn't harsh by any stretch, but it wouod have been a lot cheaper and easier to just find a frame that is more suited to what I want rather than having to Frankenstein and spend a fortune on the bike I bought to achieve the same results.
 

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LC, axle path and shock type seem to make the biggest difference to me, with the caveat that anti squat significantly more than 100% can start to feel janky, but few bikes increase though the travel or are that high (well over) deep in the travel. Axle path is a double edged sword. Disadvantages and advantages to each setup, maybe with an edge towards vertical/rearward for a DH-only bike. But apart from the other suspension disadvantages, that makes it harder to wheelie and manual.
11-6 equipped Druid owner here. A little tougher to manual but I don't have any issues doing wheelie drops or hoisting the front end over and onto root and rock ledges. The suspension locks up a little under hard braking but for anyone riding steeps, that is a welcome "flaw" - the rear end stays nice and squatted and very predictable when you are praying to the biking gods to get you down in one piece. Apart from that, nothing but joy.

I have owned well over 15 "nice" bikes and this one is a keeper. Season 3 on it. As excited today about it as the day I bought it. Biggest surprise is that it is as good a climber as it is a descender. I don't see any real downsides suspension/linkage-wise. Not for the kind of riding I do.

Don't destroy any delusions I have Jayem ?
 

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Antisquat and kickback are not the same thing but are related. It's possible to get kickback on either suspension compression or extension. Antisquat is about axle path. Kickback is about chainline vs suspension geometry. Rollers are used to completely decouple the two effects.

As for low speed vs high speed damping. Low speed is not small bump. The damping that mostly affects small bump is having a preloaded shim stack or poppet. A rear shock tuned to be more progressive (i.e. dual stage stacks or just a big LS bleed and stiff HS valving) tends to have no support for pumping the bike and also runs really rough on choppy terrain at speed.
 

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Discussion Starter · #16 ·
Ok fair enough, but I thought part of Normans argument about the new 11.6 being inferior was that Darren switched to single stage stacks and everyone except pretty much Darren in that thread was arguing dual stage stacks are better...yes my new shock is much more sensitive to small bumps than my previous 11.6...like massively so and is great in square edge hits too...but it does feel extremely choppy at speed over webbed roots, didn't know if that was the shock, the bike or if it's just normal for bikes to feel like crap over a miriad of roots crossing all over the place and the wheel catching in the troughs between them.

According to this forum the consensus seems to be 2 stage feels plusher and better for woods, but it's for moto and quite an old thread.

 

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Ok fair enough, but I thought part of Normans argument about the new 11.6 being inferior was that Darren switched to single stage stacks and everyone except pretty much Darren in that thread was arguing dual stage stacks are better...yes my new shock is much more sensitive to small bumps than my previous 11.6...like massively so and is great in square edge hits too...but it does feel extremely choppy at speed over webbed roots, didn't know if that was the shock, the bike or if it's just normal for bikes to feel like crap over a miriad of roots crossing all over the place and the wheel catching in the troughs between them.

According to this forum the consensus seems to be 2 stage feels plusher and better for woods, but it's for moto and quite an old thread.

There's a whole lot of stuff going on there. Norm's background is Moto so that's what he's used to seeing. On a moto you've got a bigger range of speeds and impacts. Having a second stage doesn't mean your initial damping needs to be softer, it just means later on you can get even more damping. If that's the goal.
Using a dual stage to make the initial damping softer in search of small bump is IMO the wrong approach. Preload, either in the main stack or base vale, is likely a big factor in what you're feeling.

I'm not familiar enough with Moto to know how much progression they have in their shock linkages. Because that's another factor in when and how the second stage can start to work.
 

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According to this forum the consensus seems to be 2 stage feels plusher and better for woods, but it's for moto and quite an old thread.
you can't generalise them like that, it depends on way more factors than just the stack shape. Piston design is a big one, so if you are designing the shock yourself you can optimise it for a particular type or maybe give yourself the option to go either way. Eg you could make the factory tunes all single stage but shape the ports in a way that it would work with 2-stage or even preloaded stacks if you want.
Or to put another way, you can have one piston + 2-stage valving create an identical damping curve to a different piston with a single stage stack. You can't put a dual stage design on any old piston because in a lot of cases the second stage will never engage
 

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Axle path is a biggy IMO.

I never really "got it" till I got a supreme. It's amazing hitting square edges but the big one for me is chainstay growth under compression. Effectively the bike gets more stable as you land a drop or huck into a sketchy section. It truly is a cheat code for increasing speed/confidence/ability just via kinematic.
 

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Well, anti is a design feature which is the consequence of a suspension arrangement. It’s the force path of any external applied longitudinal force (in this case) through the suspension that creates an upward/downwards movement. And this can counteract the load transfer.
Ofcourse it also puts you at a different path and motion ratio due to the changed rideheight.
Perhaps on a mtb going downhill it’s less applicable but on a motorcycle the rear anti-dive also plays a role on preventing the rear from coming up too much and the effect on the front caster angle.
So as long as there is an external force applied in the contact patch the antis are “active”.
 
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