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If you have too much AS then you'll lift yourself up in the travel with every pedal stroke and have bob but in reverse and it's just as inefficient as not having enough. Ridden a couple of bikes that do that.
Tends to be longer travel bikes with AS that falls a lot through the stroke - horst link, KS link (banshee). To get the AS they want in the midstroke so it doesn't wallow on the climbs, it's too high at the top of travel and bobs on the flat. It could be one reason why SC seems to be sticking with VPP for longer travel and moving to horst for shorter travel.
Being able to have a solid ~120-130% AS through the entire travel without high levels of associated kickback is one reason why I actually quite like true high pivot trail bikes for climbing, even though the drivetrain isn't as efficient. The bike can be extremely responsive and stiff under the pedals, but the wheel still glides its way over anything, and you gain some "efficiency" back because you don't have to put as much body-english into managing your grip or preventing stalls.
edit: sorry Mr Suslab, restated your point because I hadn't refreshed my page.
Following two experts is a bit intimidating, but as far as the Tallboy, the curves match a lot of other pedal-focused bikes and I think may be the current consensus on the kinematics for that genre I've always understood that the lower anti-squat pairs with the lower starting leverage ratio, and the lower leverage ratio is the first domino in that chain. Because leverage is lower, you don't need as much anti-squat. Then you rely on the lower volume air shock to ramp up to prevent bottom out. I don't know enough to have a truly informed opinion on whether this is actually "better" for a bike like the Tallboy. Obviously this doesn't apply for the Nomad.
What does seem a bit strange to me is that they shifted the kinematics of the Tallboy in a very XC direction while also upping the travel and biasing the geometry more towards descending. The travel probably has a lot do with travel numbers on the Blur and Hightower. Regardless, I think I may be into it. I'm interested in adding a more XC bike to my fleet, but don't want to be in an XC position on the bike. With the stack on the Tallboy, seems like you could set up the suspension on the firm side, build the frame up light-ish, and get the bike I'm interested in.
Lower anti-squat pairs best with a more progressive bike due to the increase in mid-stroke support. If there's more support when you're bobbing, you don't bob as much so less anti-squat is fine. The actual leverage ratio number isn't hugely important so long as the shock is tuned properly for it and the rider is able to get settings within an reasonable range. The previous rendition of the Tallboy didn't have crazy high anti-squat and the new version doesn't have crazy low anti-squat so to me it's just a different spin on how you prioritize pedaling. In my mind it's more in line with the model of predominantly pedaling while seated. I believe you need slightly higher anti-squat if pedaling standing is a priority since it's harder to be smooth in that scenario.
I too find it interesting that the kinematics went in a XC direction while other aspects of it went the other way. Although you could say the braking behavior of a Horst link bike is more suited to lower angle terrain so that's a little more XC as well.
Just wanted to express my gratitude for everything shared in here. It has been insanely huge for helping me learn along the way.
Lol yeah I do the same thing - I'll have a page open all day and write a reply after its moved on several posts or pages!
And yeah the Banshee bikes had a really strong pedalling reaction like that - so did a lot of Mondrakers. They might have changed things recently but that was definitely the trend for a while. I remember when the MS team first switched to the Summum I found it was a super fine line where a 325 spring was plush and pedalled well, and a 350 was better suited for big bumps and speed but bounced wildly on the pedals
@Shinook copying this over to here so as to not continue blowing up tech rumors...
What I read into this is it's a case of stiff compression tune being used to provide the necessary bottom out resistance. Tires can be quite effective when it comes to ironing out the really little stuff. Square edge hits require a high shaft speed for the wheel to clear with minimal disruption to the chassis. The shock has no way of discerning between high shaft speed because of a drop or similar and high shaft speed because of a square edge. So the stiff damping tune that prevents bottoming also causes it to kick/hang up on square edges more.
A bunch of comparisons mainly looking at wheel force because that's what you really feel not the leverage curve.
160 mm bikes with different progression amounts normalized for identical sag at the wheel. Including -4%. The wheel force plot is purely looking at wheel force due to the spring. As you can see, there is a very significant difference at bottom of travel. If you were to zoom in on the sag point, you can easily see that a more progressive bike has a lower force at all points before the sag point and a higher force at all points after the sag point compared to a less progressive bike.
Wheel damping is the other interesting one. This plot just compares how the leverage curve influences damping force as felt at the wheel. Keep in mind these curves can all be more or less adjusted up and down with damping tune. It's set so that it would be comparing the same tune with the adjusters in the same place. To me the cool thing with a more progressive leverage curve is that you get a ramp in the damping force as you feel it at the wheel. You could argue that, because of this, a bypass shock wouldn't be useful as you already experience different damping responses at different points in travel. I'm not really sure why anyone would want the damping tune to feel softer as you get deeper in travel.
There was another comment about progression vs travel in the other thread. Same comparison as above but with identical progression and different travel and shock sizes. I don't really see a reason you'd want to pick progression numbers so that the derivatives of each of these curves would be identical. The shorter travel bike is already giving up a ton of bottom out resistance. I know a shorter travel bike shouldn't be ridden like a downhill bike, but there are still a lot of fun things to do on 140 mm bikes that requires significant bottom out resistance.
The damping plot. You really don't need a longer travel bike to feel as stiff so you could maybe say using the same damping tune one these different setups makes sense.
I conceptually knew that high progression changed damping but its cool seeing an example of it.
Related to bottom out, do you have any sense (either in % of wheel force or a rough number) that most HBO shock systems exhibit?
Is this value greater or less than foam bottom out bumpers? I'm guessing the answer is, it depends. I'm aware of the tradeoffs of bumpers (namely they increase rebound speed.
HBO can exert anywhere between way less and way more force than a rubber bumper since it’s dependent on the speed of compression. And then, like you said, it doesn’t increase rebound speed compared to a rubber bumper. The one argument you could maybe make for rubber bumpers is that there are some scenarios, like a long sweeping berm, where having additional support from the shock that isn’t speed dependent is beneficial. If shaft speed is near zero then HBO offers very little additional support so you’d continue to settle into travel. That would actually be a bigger deal on a more linear bike since they tend to blow through travel in berms more.
Can anyone here calculate the leverage curve and progression % on the new Evil Offering V4?
Second this, this would be awesome. As I am puzzling on dialing in setup and want to understand some of the minor changes that apparently have been made.
I also have a Murmur and have tried both coil (CC Tigon) and air (2027 RS SDU) in the 135mm setup. I've actually found I prefer the air shock in all scenarios, although I do run a bit more HSC than usual.
I have been told multiple times, by multiple people that a coil shock helps with resisting bottom outs with better “mid stroke support”. As someone who often struggled with excessive bottom outs (using max volume reducers, etc) I’ve been skeptical of this. Only thing that really helped was getting a 170 travel bike with 29% progression and a fairly progressive shock (superdeluxe instead of x2).
Am I overly focused on the progressivity, or am I actually missing something with the coil shock thing? I admittedly haven’t tried a coil shock, because I’ve been afraid it will make things worse for me, not better like some people say.
Looking at the graphs cascade posted I REALLY don’t get this coil shock thing.
Don’t have the dimensions for the V4 offering so not able to plug that in. I’d imagine it’s like the previous ones where the majority of the progression happens earlier in travel though.
It depends on the shape of the spring curve for the air spring. The curve has a vague S shape to it. Initially it will be stiffer than a coil, then softer, and then stiffer towards end of travel (or not in some cases). A small volume air shock can have an insane amount of ramp to offset that mid-stroke range so the bottom out resistance from one of those is hard to beat. Meanwhile large volume air shocks often have worse mid-stroke and bottom out if they don’t have volume spacers installed. See the Vivid below.
What kind of measurements would you need to pull up a chart like the one on the website for the v2 link?
Here goes the results from sticking an image in to Linkage, so there is potential for some error but is close to what I've seen elsewhere and shows 26% progression, but most of that is early on as Cascade predicted
Thanks!
Interesting, so just a touch more progressive than the V2 and with 10mm more travel given by the 5mm extra stroke
Great question. I'm going to try to restate more globally, as I'm curious about the premise itself.
I've always understood the argument to be a defensive one, "Sure the air shock ramps up more at the end of the stroke, but the coil is firmer in the middle of the stroke, and it's the entire area below the force line that matters. You can't just look at the end point to determine bottom-out resistance."
Is the-entire-area-under-the-force-curve a valid way to compare bottom-out resistance? Seems like it would depend on where the shock is in its travel when the compression begins - e.g., drop vs. big square edge in the middle of a high speed rock garden?
Entire force under the curve is the drop to flat type scenario. For square edge hits you can still look at area under the curve, though. It just starts from whatever the initial position of the shock is instead of zero. If you were to say you’re cruising along and then slam into a really big bump that’s big enough to bottom out, you’d be looking at the integral from the sag point to full compression. If we were to compare the Vivid with no volume spacers to a coil, it actually looks even worse than the drop to flat scenario. With the Vivid full of volume spacers, it would be harder to bottom out if you encountered an impact while starting at 60 mm of shock stroke. When your wheels are already on the ground the fork tends to take the brunt of the impact so there aren’t a whole lot of bottom out events for the shock with wheels already on the ground other than g outs. This applies to air vs coil forks as well though.
Damping is a huge factor in bottom out resistance and much harder to quantify since people can have it set all over the place and depends on shaft speed. Since work done by the shock is the summation of work done by the spring and damper, it is reasonable to say anytime the work done by the spring is increased bottom out resistance increases as well. Similarly anytime the damping tune is stiffened bottom out resistance also increases.
It's hard for me to imagine a scenario where I'm hitting the bottom out bumper on a long sweeping berm and not experiencing high shaft speeds.
For me, I shouldn't be going past maybe 70% of travel on a long sweeping berm, even if I'm coming real hot. If I'm using more travel than that, it means that I'm either running into the turn violently or hitting braking bumps, holes, roots, or rocks in the berm, all of which would create high shaft speeds and activate HBO.
Just spitballing here, but to me HBO seems like a huge advantage everywhere compared to relying on a piece of rubber to do the same job. I've liked all the shocks I've ridden with HBO, but this was really driven home for me on the Push Nine One fork because it erased all high-force or bottom out sensations from my hands, and removing those scary sudden shifts of my center of mass over the front axle.
But please prove me wrong if I'm missing something.
*a caveat: I stay away from linear/low progression bikes like the plague, and in that case that you mentioned, a rubber bumper may be helpful. But I'd argue that, in that case, it's really acting as an aftermarket "more progression" hop up kit for a bike that isn't progressive enough for the user.
Yeah on a more supportive bike it's not happening. The amount of time I spend around 70% on the SJ15 in all it's linearity with the Genie is wild though.
Personal preference but I’ve found I prefer bump stops and volume spacers to HBO. I like HBO as a tool to quickly add bottom out support when I go ride stuff with bigger impacts than I have my setup tuned for (ie park riding vs trail riding) but I don’t like how it feels like you’re jumping on a memory foam mattress when trying to use a rock or a bump to generate some pop to get the bike airborne.
On the Vivid air I’d tune volume spacers for trail riding and when I took the same setup to the park I’d use HBO for the bigger jumps and drops. Im on a Telum now and use a similar tuning philosophy since its got a rather stiff bottom out bumper.
Yeah a long, sustained berm high-g can compress the suspension at slower speeds on certain bikes so the HBO is less effective. You can feel this with some bikes that can bottom out just by bouncing in the carpark or preloading for a bunnyhop but don't bottom out when you land that bunnyhop, or even very often on the trail. Its probably too soft for you one way or another but it does show how bottom outs can occur in unusual places.
But yes this does normally happen on less progressive frames, and it does mean you run out of travel for absorbing bumps mid corner
I do like combination of both - I think a bumper can give a more progressive engagement (although the smashpot V2 has a way to gradually engage the HBO) for smoother energy dissipation, but an HBO can potentially absorb more total energy in very large impacts. The ratio of each component probably changes depending on the linkage though, a linear frame suits the extra spring and support of a bumper, while a progressive frame will benefit more from an HBO because the bumper will feel more abrupt.
It's also been interesting how many people talk about HBO systems while a lot of them think their shocks are "overdamped" or set the damping as light as possible - you probably wouldn't need the HBO as much if you had adequate damping for the rest of the travel. I can't remember where it was but I swear I remember one reviewer saying they prefer as little compresison damping as possible, then later in the article praised the HBO, but wished it had effect over more of the stroke......
Also FYI the Nine-One also uses a roughly 20mm tall elastomer bumper in conjunction with the HBO. Another thing thats not often pointed out in their elevensix shock is they have very finely tuned bottom out control where the HBO, bump height and bumper engagement are all optimised for each frame. Which means 2 bikes that take 62.5mm stroke shocks can have very different configurations depending on what exact frame it is intended to go in to. Not shilling for Push here, just pointing out how both technologies can be used together for the best result
This is great info, and I didn't realize that the Nine One had a fat rubber bumper lurking at the bottom. Thanks for the lesson!
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