[Pslide]

Right, I'm usually answer more questions than I ask, but after watching Santa Cruz's APP videos and reading some of their marketing speak, I've got a question.

They've designed their APP bikes (Nickel, Butcher) to mimic the VPP shock curves, which start off falling rate and then go rising rate. The falling rate part at the beginning of the stroke always made me scratch my chin - why? Why not just have a nice progressive rate all the way through?

Here is an example - Nickel vs. Commencal Meta 5.5.

Santa Cruz says thus: "What this means is that during the initial falling rate part of travel, the suspension is very responsive to bump forces - it uses more of the suspension for a given bump size. Basically, this feels like "more travel" than is really there."

I can understand that because it's falling rate, it will blow through the travel a bit quicker. But a progressive curve will start at a lower rate initially.

So which is better for traction and small bump absorption? Start low progressive rate, or start high and falling rate?

Anyone ridden two bikes with those linkages and can speak from experience?

(I'm considering a Nickel for my trail bike.)

 

[tacubaya]

Right, I'm usually answer more questions than I ask, but after watching Santa Cruz's APP videos and reading some of their marketing speak, I've got a question.

They've designed their APP bikes (Nickel, Butcher) to mimic the VPP shock curves, which start off falling rate and then go rising rate. The falling rate part at the beginning of the stroke always made me scratch my chin - why? Why not just have a nice progressive rate all the way through?

Here is an example - Nickel vs. Commencal Meta 5.5.

Santa Cruz says thus: "What this means is that during the initial falling rate part of travel, the suspension is very responsive to bump forces - it uses more of the suspension for a given bump size. Basically, this feels like "more travel" than is really there."

I can understand that because it's falling rate, it will blow through the travel a bit quicker. But a progressive curve will start at a lower rate initially.

So which is better for traction and small bump absorption? Start low progressive rate, or start high and falling rate?

Anyone ridden two bikes with those linkages and can speak from experience?

(I'm considering a Nickel for my trail bike.)

The regressive stage is only changing ratio from 2.4 to 2.58, not that much... so it would probably feel kinda linear really. XC and Trail bikes tend to be regressive while AM and DH bikes tend to start up and decrease ratio (progressive). The advantage of starting with high ratio is the elimination of shock and linkage stiction, while ending in a much lower rate enables it to prevent bottom out.

If you look closely too, apart from the small range of values in the regressive stage, you will probably see that the sag point is very into the regressive curve, so it doesn't matter really as you will probably be over the sag point (and into the progressive stage) most of the time.

 

[Owennn]

Santa Cruz also used to say their VPP had an S shaped axle path, among other things.

Handle Santa Cruz's marketing and engineering advertising with great care.

 

[Pslide]

@Tacubaya: Good points I agree with. And you'd think a starting with a high lev ratio would be even more preferable to overcome the initial stiction with air shocks on AM bikes. And yet SC has purposely designed it falling rate in the beginning stroke. It would have been super easy to create a progressive curve throughout, but they chose not to. Kinda interesting to me. I suspect they know their stuff.

@Owennn: I hear you there. But SC's marketing of these new APP bikes seems pretty legit. Watch the three videos they have on their website and it's all straight talk.

 

[Sandwich]

Everything I've read has suggested that a falling rate is no bueno for mountain bikes...lends to blowing through travel, firm small bump compliance, and extremely plush big hit performance. On the other hand, progressive rates offer very good small bump compliance but don't bottom out on big hits. I've ridden very progressive bikes and they offer a great feeling throughout the travel, both in compliance and in knowing what your bike is doing...ie, I could tell when I was near bottom out or deep in the travel, and use that to my advantage, particularly in berms.

People will tell you what they want you to buy, or that they can sell. My guess is that Santa Cruz came up with this idea because A) It was patentable, B) Patents sell in mountain biking (Look at the three threads on Split Pivot) and C) They could tell you it was better, without needing to tell you why or how.

 

[fluider]

I think there is some terminology incompatibility in here, isn't it?
Falling rate of leverage ratio makes progressive suspension (progressive or rising shock rate). And wise versa.

 

[ZoRo]

People will tell you what they want you to buy, or that they can sell. My guess is that Santa Cruz came up with this idea because A) It was patentable, B) Patents sell in mountain biking (Look at the three threads on Split Pivot) and C) They could tell you it was better, without needing to tell you why or how.

Q4T! Add to that the fact that they wanted to create a marketing buzz for a new suspension technology as good as their upper echelon VPP platform, but targeted to a more *budget* oriented crowd (gasping as I'm typing that). I still don't understand why they didn't downgrade the VPP on lower priced bikes...

 

[Sandwich]

Q4T! Add to that the fact that they wanted to create a marketing buzz for a new suspension technology as good as their upper echelon VPP platform, but targeted to a more *budget* oriented crowd (gasping as I'm typing that). I still don't understand why they didn't downgrade the VPP on lower priced bikes...

I doubt they pay much for VPP licensing to Outland, the now defunct and never very successful MTB company, who oddly used a falling rate on their original VPP5....which suggests...why the hell can't they dumb down the aluminum quality and make a cheaper entry level frame? Oh yeah, because then why would you pay big bucks for the daddy frame?! Releasing a linkage SP bike elevates their VPP tech as well as offers a low end affordable bike, and then you have the carbon frames as the icing on the cake. Smart business sense, but we/beginners end up getting jipped.

 

[mtg]

Yeah, that doesn't make any sense. I've ridden a Nickel, and my butt dyno confirms that the suspension is progressive (and I'm used to riding progressive frames).
My best guess is that there was a disconnect between engineering and marketing somewhere. I'm an engineer, and reading some of the marketing of stuff I design induces facepalms on a regular basis.

 

[marshalolson]

a high leverage ratio number means it is easy to overcome the spring (plusher). a low leverage ratio number means that it is hard to overcome the spring (firmer)

the commencal is easy to overcome the spring at the beginning of the stroke, and harder and harder the further you go into the travel. this is called progressive.

the SC is hard to overcome initially, gets easier in the middle of the travel, and firmer again at the end of the travel.

from there YOU have to determine what you want. some folks will think the SC pedals awesome, is plush in the middle, but does not bottom out. others will think it has sh!tty small bump compliance and will blow through the mid-stroke, and have a short ramp-up on the top end. some folks will think the commencal has awesome small bump and feels super smooth. others will think it pedals poorly and that they maybe are not using all of their travel.

hope that helps.

 

[Pslide]

@fluider: Yes, you're right. It's a discrepancy I think everyone accepts. "Rising rate" is actually falling leverage rate.

@mtg: Your butt is not lying to you. The Nickel is progressive past the sag point - where it counts. Thanks for the mini-review though, I'm definitely seeking a progressive bike.

But I'm interested in what is going on before the sag point, just because I think there are two design philosophies opposite of each other but both make sense to some degree.

@Sandwich: We wouldn't want falling rate for the suspension past sag point (which is why I'm getting rid of my Balfa 2step BTW), but doesn't falling rate before the sag point kinda make sense? That is when you want your suspension to give easily for small bump compliance...

 

[mtg]

What I meant is that the suspension feels progressive throughout all of the travel, not just past the sag point. I'm calling bs on the graph from SC- you don't want regressive and I don't think it actually is regressive. I think somebody in the marketing dept is confused.

 

[Sandwich]

I certainly can't say for sure, I'm no expert nor engineer and my advice/commentary is entirely based on personal experiences and evidence from professional and personal reviews...

but I feel like it'll be a moot point, and my preference lends towards suspension performance rather than goofball methods of controlling bad pedal stroke. I've been riding suspension bikes since 96 and have rarely or never felt the need for pedaling platforms IF you don't pedal like a monkey. To that note, I'd rather have a linear to progressive shock rate (ie progressive) to get very good small bump compliance and big hit resistance.

I also feel like on the trail, you'll rarely notice what the shock is doing below/before the sag point, because you'll either be above it while standing, at it while seated, and only before it when landing or over a pothole...in either case I'd rather have faster rebound and lighter compression to get me back into mid travel as fast and smoothly as possible, rather than having an overdamped harsh feeling intially...does that make sense? I hope I'm explaining what I'm thinking...

In the end, I think it's a solution to a problem nobody needed a solution to. If you're a really bad pedaler, firm damping on either end may help, but I don't know if I see the need.

 

[tacubaya]

@Tacubaya: Good points I agree with. And you'd think a starting with a high lev ratio would be even more preferable to overcome the initial stiction with air shocks on AM bikes. And yet SC has purposely designed it falling rate in the beginning stroke. It would have been super easy to create a progressive curve throughout, but they chose not to. Kinda interesting to me. I suspect they know their stuff.

Also it must be the way the link rotates. If you see the Nickel, you can clearly notice that the link will compress the shock a bit easier than further into the stroke. So maybe the curve will be always inherited from the APP design (if they keep pivot locations more or less equal)?

The falling rate at the first stage will probably enable the bike to reach sag point efficiently and smoothly as well as improve small bump compliance a bit. I doubt SC calculates sag with a leverage table like Banshee does.

Even if it is regressive, it is still moving the shock piston.. actually faster than in the progressive stage, so it may have something to do with the coupling to the fox air shock and the ability of that shock to generate damping in that range of the stroke.

If the shock can't generate enough damping at the beginning at certain speeds, then the bike can be adapted to be regressive, then the shaft will travel at higher velocities in the regressive stage and thereby generate enough damping force in the shock.

Some ideas.

 

[Pslide]

@mtg: I don't think this is marketing speak. Watch the 3rd video here: http://www.santacruzbicycles.com/nickel/ It has the engineers behind the bike saying why they designed the leverage curve the way they did (regressive than progressive). 2nd video is also good. (Edit: OK, not "why" - otherwise I wouldn't be asking...)

@Sandwich: Well said and possibly true. I suspect I'm splitting hairs. Hopefully I'll get to ride one and decide for myself if I can feel what the curve is doing. Doubtful, eh?

 

[time-bomb]

I guess I am echoing what Sandwich just said but does it really matter what happens before Sag from a compression standpoint? You rarely, if ever, ride above the sag point so I am not sure why it would be relevant (but I may be overlooking something). Seems like over engineering or trying to fix a problem that doesn't really exist. I think the most critical part of suspension is what is going on at the point of sag and later. Again, echoing what Sandwich said, the most import thing about the suspension above the point of sag is its ability to respond to holes (negative travel), the rear wheel falling into them and then returning to the point of sag again as quickly and smoothly as possible.

I believe the original Hecklers (and many other SP bikes from that era) were designed to be regressive so that they had a pedaling platform built into them but that did result in bottoming out easier.

 

[tacubaya]

I guess I am echoing what Sandwich just said but does it really matter what happens before Sag from a compression standpoint? You rarely, if ever, ride above the sag point so I am not sure why it would be relevant (but I may be overlooking something). Seems like over engineering or trying to fix a problem that doesn't really exist. I think the most critical part of suspension is what is going on at the point of sag and later. Again, echoing what Sandwich said, the most import thing about the suspension above the point of sag is its ability to respond to holes (negative travel), the rear wheel falling into them and then returning to the point of sag again as quickly and smoothly as possible.

I believe the original Hecklers (and many other SP bikes from that era) were designed to be regressive so that they had a pedaling platform built into them but that did result in bottoming out easier.

 

[Sandwich]

@Sandwich: Well said and possibly true. I suspect I'm splitting hairs. Hopefully I'll get to ride one and decide for myself if I can feel what the curve is doing. Doubtful, eh?

the only way to figure out what works and what doesn't, I think, is by riding one or something like it and finding out. I've never owned one of these so it's all theory, but I've owned a Cannondale prophet, which had a full falling rate, and currently own a sunday, which is progressive to linear to something?

The cannondale performed exactly like a falling rate should. It had a tendency to transmit every small bump in the road, then nearly bottom out on anything bigger. While I had a crappy shock on there, it didn't inspire any confidence that the bike would be magically healed by a slightly better shock. You'll notice that they now use an extremely similar design but have added a rising rate linkage (moto).

The Sunday has a somewhat vague midstroke feeling and I do feel it bottoms too easily, but the rest of the bike is just so dang good I overlook it.

FWIW, my previous DH bike was a Racelink which had a very progressive rate. It was my favorite performing suspension on a bike, was super plush (they designed it with 2-3mm of sag under it's own weight, or twas the rumor), and had great feedback as to where I was in the travel. I could feel it ramp up but it never seemed to bottom. I still think I had too soft of a spring on there too.

In the end it comes down to rider preference, but I really think a simple progressive rate is the best option for riders who know how to pedal!

 

[time-bomb]

ha-ha

not saying you are wrong, but educate me on this. you sit on a bike, it sags, you pedal and go. sure, that is an over-simplification but really, how much riding is done above the point of sag when you are actually pedaling? there are times going through chop or whoops but you aren't really pedaling then.

 

[Sandwich]

ha-ha

not saying you are wrong, but educate me on this. you sit on a bike, it sags, you pedal and go. sure, that is an over-simplification but really, how much riding is done above the point of sag when you are actually pedaling? there are times going through chop or whoops but you aren't really pedaling then.

I think his comment was WRT above sag vs. below sag. The wheel is rarely "below" the sag point relative to the bike. I think you're thinking "above" in the reverse order, ie on paper or whatever.

 

[time-bomb]

I think his comment was WRT above sag vs. below sag. The wheel is rarely "below" the sag point relative to the bike. I think you're thinking "above" in the reverse order, ie on paper or whatever.

True. I should have specified either the wheel or the rider. My comment was based on rider position relative to the point of sag, not the rear wheel. With that being said, I could still be off base

 

[Pslide]

Even if it is regressive, it is still moving the shock piston.. actually faster than in the progressive stage, so it may have something to do with the coupling to the fox air shock and the ability of that shock to generate damping in that range of the stroke.

If the shock can't generate enough damping at the beginning at certain speeds, then the bike can be adapted to be regressive, then the shaft will travel at higher velocities in the regressive stage and thereby generate enough damping force in the shock.

Some ideas.

Hmmm, you could be on to something here. I wonder if it better controls the negative travel at speed (wheel falling into hole). With a full progressive rate, the damper has the least control at zero travel, so as you say, by adding some regressiveness it will give the damper more control - perhaps reducing chatter in negative travel (by controlling how much the wheel drops into a hole).

It may also be part of the pedalling platform. From the sag point it would increase damping with negative travel - since bob is equal parts positive and negative travel.

I'm starting to come around to this idea - at least theoretically.

 

[Vrock]

The Leverage Ratio on the Blur, Blur LT and Nomad is like that and I don't like it, it blows thought the mid travel, but i've meet a few people that like it. Why did SC choose the same LR on the Nickel and Butcher??? I don't know.

The problem with the Blur and the Nomad is that SC can't use a nice progressive ratio all the way. If they could, they will do it. But I've tried many times and I think it's impossible. When the shock is attached to the upper linkage, the bike tends naturaly to that kind of leverage Ratio.

The only way to do it is to attach the shock to the lower link, like the V10 or Driver, but the problem is that those bikes needs a front deiralleur, so it would be very difficult to do It. Maybe with an extension like Sunn???

The APP on the other hand can be designed with any kind of LR, but they used the same... Problably to support the VPP bikes, to keep the same looks, to use the same parts...

 

[Pslide]

PS - The new Orange 225 linkage was also designed with this shape curve. I asked Rowan Sorel on a training day why and he said it was by design, to create a pocket around the sag point. I didn't really understand the theory then, but he said it felt great.

 

[tacubaya]

Hmmm, you could be on to something here. I wonder if it better controls the negative travel at speed (wheel falling into hole). With a full progressive rate, the damper has the least control at zero travel, so as you say, by adding some regressiveness it will give the damper more control - perhaps reducing chatter in negative travel (by controlling how much the wheel drops into a hole).

It may also be part of the pedalling platform. From the sag point it would increase damping with negative travel - since bob is equal parts positive and negative travel.

I'm starting to come around to this idea - at least theoretically.

Yeah. Although I must say that the range of regressiveness in this bike is very little (0.18 mm/mm) so I don't think that the leverage change will produce such dramatic velocity change to alter the damping forces at the beginning of travel (being positive or negative).

BUUUUUUT, it would definitely translate into a little bit more chassis control under holes, SBC, and pedaling as hydrodynamic damping is proportional to the square power of the velocity, so even a little bit of velocity change will make a noticeable difference.

Dunno, just a bunch of theories. I bet that you can't feel much of that change in leverages while riding... maybe the wheel rate could bring a better idea on how the bike feels?

 

[alexhill]

I swear no one has cared before now, and rather guessing by leverage curves and bollocks, people just tested bikes and thus decided which one was better.

Go test ride them, that'll tell you which one will be a better trail bike for you.

 

[TrueScotsman]

Can I suggest something;

If the bike was designed around an air shock (progressive in nature) maybe the (small) amount of regressive travel at the start of the SC Nickel travel would be "cancelled" out and become linear( + + - = 0). It would then become increasingly progressive as the shock bottommed out. So the actual wheel rate would be linear to extra progressive.

I would have to see the shock rate graph of an air shock to see if this theory is true.

What d'ya reckon?

 

[Vrock]

Can I suggest something;

If the bike was designed around an air shock (progressive in nature) maybe the (small) amount of regressive travel at the start of the SC Nickel travel would be "cancelled" out and become linear( + + - = 0). It would then become increasingly progressive as the shock bottommed out. So the actual wheel rate would be linear to extra progressive.

I would have to see the shock rate graph of an air shock to see if this theory is true.

What d'ya reckon?

Nope, an air shock is hard-soft-hard. So when you combine it with a regresive-progressive Frame the wheel rate is very hard-very soft-very hard.

To get a Linear feeling with an air shock you need a leverage ratio like the Ibis Mojo, Banshee Rune.... Progressive-Regressive.

 

[eatmyshorts]

my thoughts are that it the shock curve is dictated by packaging. The overall design of the frame is very similar to the standard heckler - eg swing arm shape - position of upper shock mount. There is only a small number of ways you can simply configure the links in this arrangement. The shock rate maybe is a result of this?

 

[tacubaya]

my thoughts are that it the shock curve is dictated by packaging. The overall design of the frame is very similar to the standard heckler - eg swing arm shape - position of upper shock mount. There is only a small number of ways you can simply configure the links in this arrangement. The shock rate maybe is a result of this?

Of course.

 

[gemini2k]

I think pretty much anyone who's ever ridden a falling rate FR/DH bike can attest to the fact that they basically feel like ass in all conditions, save the occasional extended pedal section. Can't figure out why anyone still does it.

Harsh off the top, sh*t small bump compliance, and horrible unpredictable bottoming on mid to big sized hits, the best of all worlds on a long travel bike?

 

[lanceamatic]

I'm going to guess that 1/2 the people in this thread can't tell that the graph is showing "shock ratio", which is the inverse of "bike ratio".

even though the curve goes up then down, The graph shown is "regressive" until 35% travel (43mm or so) then switches to "progressive" until bottom out.

 

[tacubaya]

I'm going to guess that 1/2 the people in this thread can't tell that the graph is showing "shock ratio", which is the inverse of "bike ratio".

even though the curve goes up then down, The graph shown is "regressive" until 35% travel (43mm or so) then switches to "progressive" until bottom out.

The graph is showing leverage ratio (frame) as in how many mm of vertical travel you get per every mm of shock shaft movement.

Shock rate is the inverse.

 

[eatmyshorts]

We don't know exactly how the shock is turned - eg change of the spring rate through the stroke compression tune..

Using larger air cans change the mid to end stroke properties significantly - try running a large air can on the old heckler... or not a progressive (non 5th element) coil = blowing through the mid and end stroke..

We cant see the whole picture here...

 

[tacubaya]

We don't know exactly how the shock is turned - eg change of the spring rate through the stroke compression tune..

Using larger air cans change the mid to end stroke properties significantly - try running a large air can on the old heckler... or not a progressive (non 5th element) coil = blowing through the mid and end stroke..

We cant see the whole picture here...

You can suppose that the Float shock in there is just that... a Fox Float shock. We know how it behaves and I doubt they are tuned for the frame.

 

[eatmyshorts]

You can suppose that the Float shock in there is just that... a Fox Float shock. We know how it behaves and I doubt they are tuned for the frame.

What makes you doubt that it is custom tuned? I thought this is pretty common place with most manufacturers?

This is straight of the fox website...

It provides velocity and position-sensitive damping that can be designed into the beginning of the stroke, the end of the stroke, or both at the same time.

 

[JCL]

You can suppose that the Float shock in there is just that... a Fox Float shock. We know how it behaves and I doubt they are tuned for the frame.

I think there are three different compression tunes for OEM Fox air shocks. Not sure if that is achieved with valving or air can volume though.

 

[eatmyshorts]

It is achieved with different valving - some manufactures offer hi volume air cans...

My point is the shock type, tune etc plays a huge part in the overall feel... unless you apply that data to the frame rate then you cant see the whole picture..

Yes if you install random shock "A" in frame "A" with a certain frame rate, then install it in frame "B" with a different frame rate you will notice a different feel.

The small amount of rate change at the start of the travel possibly makes nil difference depending on the tune of the shock - who knows...

 

[tacubaya]

It is achieved with different valving - some manufactures offer hi volume air cans...

My point is the shock type, tune etc plays a huge part in the overall feel... unless you apply that data to the frame rate then you cant see the whole picture..

Yes if you install random shock "A" in frame "A" with a certain frame rate, then install it in frame "B" with a different frame rate you will notice a different feel.

The small amount of rate change at the start of the travel possibly makes nil difference depending on the tune of the shock - who knows...

Of course. But we were talking about the Nickel with a Fox Float right?

 

[eatmyshorts]

yes.. but we are still assuming that the nickel is using a non specific tune fox float.. not one that is specifically tuned.

I am illustrating that because you dont know how the shock is tuned - you cant assume how the shock rate will feel overall..