New School Geometry Back In Time...

[evdog]

Intense is definitely giving Yeti a run for title of most Bro-brah

[kidwoo]

Intense is definitely giving Yeti a run for title of most Bro-brah

They're pretty much the same brand in my opinion. One sells to the image of hot rod socal, the other to the vermont transplants that bro-ed their way out to colorado to join the mountain tribe. Both with image over quality and both sustaining on that image alone.......with each having pretty legit places in history in the early days. At least there's that.

[EWG]

*beece shuffles off to the corner because he really likes his Tracer 275 and VPP in general, but is now starting to accept that his tastes might run to the old school here and there, and at least he’s now drinking more East Cost IPAs than West Coast IPAs from SoCal, but still maybe he can back off into the corner so no one sees that he has an Intense and 4 more Santa Cruzes in his garage. Awkward. Still, he likes the way they ride...*

[jm2e]

beece, time to jump on the anti-bro-brah wagon of elite Bros & Brahs. We fart in your general direction!


Sent from my iPhone using TGR Forums

[kidwoo]

Current intense frames are an entirely different universe these days.

I was more commenting on how they made it up to that point.

[HAB]

Current intense frames are an entirely different universe these days.

I was more commenting on how they made it up to that point.

Do they make anything good now? I completely stopped paying attention like 7 years ago.

[kidwoo]

Look at some of the leverage curves on some of the current bikes.

I've looked at enough of them to know that they're straight, that's already an improvement. There's something to be said for outsourcing for certain companies.

[jm2e]

When you say “look at the leverage curves”, what exactly do you mean? Is there a website with leverage curve graphics? I don’t think most people (myself included) have much more than a vague grasp of the concept.

I stopped considering Intense when I saw multiple catastrophic failures.


Sent from my iPhone using TGR Forums

[HAB]

Look at some of the leverage curves on some of the current bikes.

I've looked at enough of them to know that they're straight, that's already an improvement. There's something to be said for outsourcing for certain companies.

[kidwoo]

I said bikes, not 29ers.

[HAB]

I said bikes, not 29ers.

They make that bike in a 27.5" too.


I will admit to cherry picking the worst one I found in 20 seconds of searching, but the DH bike is the only one that actually looks good.

[jm2e]

I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


Sent from my iPhone using TGR Forums

[HAB]

I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


Sent from my iPhone using TGR Forums

Short version: It's a graph of how much the rear wheel moves per amount of rear shock compression, across the full travel of a bike. So to use the Primer that kidwoo and I are making fun of as an example, it starts off at ~2.93:1, i.e. 2.93mm of rear wheel movement per mm of shock compression, is digressive for a while up to a peak of about 3:1 around sag, and then drops off to about 2.25:1.

That isn't the worst example of it the bike industry has ever put out, but those kinds of banana curve leverage ratios are pretty common. That digressive bit at the start of the travel kind of sucks because it makes the bike mushy and wallowy around sag (you have a high leverage ratio, i.e. the wheel has a big mechanical advantage over the shock around there).



Those are all examples of what a better curve looks like.

[toast2266]

I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


Sent from my iPhone using TGR Forums

To add to what HAB said, the goal (theoretically) with the kind of leverage ratio on the Intense is to make the bike supple over small bumps, pedal reasonably well, and not bottom out too easily.

So the beginning of the curve (left side of the graph, 0-40 mm suspension movement) is regressive, meaning the rear axle has more leverage over the shock at 40 mm travel than it does at 0 mm travel. Thus, hitting a bump that moves the suspension through that first 40 mm of travel moves the suspension pretty easily because, as the suspension compresses, it's gaining leverage over the shock.

In the 30 - 60 mm range, the leverage curve inflects. This is roughly the sag point of the suspension, and the curve transitions from getting easier to compress the shock, to getting harder to compress the shock. Putting that inflection right around the suspension's sag point (~30%) will maybe help the bike feel a little snappier on the pedals.

The rest of the curve (50mm - bottom out) is progressive, meaning that the bikes leverage over the shock decreases as the suspension compresses.

If this were a linear suspension with a coil shock, the amount of force to compress the shock is easy to calculate - with, say, a 400lb spring, it takes an extra 400lbs of force to compress the spring for every inch of compression. So that's 400lbs of force for the 1st inch, 800 lbs for the 2nd inch, 1200lbs for the 3rd inch, etc.

That same 400lb spring on this suspension will take additional force, because the leverage ratio isn't linear. So it might take 350 lbs for the first inch (because the leverage ratio is regressive, and then flat-ish), But then 1000 lbs for the 2nd inch (since the latter half of the leverage curve has a falling rate, has less leverage over the shock, and thus takes more force to compress the spring). This is why some bikes work well with coil shocks, and some don't. Air springs are naturally progressive, so they work better with less progressive rates. Coil springs are not progressive (progressive wound springs being an exception), and therefore benefit from a more progressive suspension design.

As far as what's actually good or not, there are pretty clearly personal preferences on that front. The more uniform the leverage curve (like the Geometron curve that HAB posted), the easier it is to tune the shock around the curve, and it generally means the suspension is more predictable. Particularly for anyone riding the bike actively (pumping, jumping, etc.), that can be preferable. But other suspension designs can be made to pedal a bit better while potentially maintaining suppleness / traction at the beginning of their travel, usually at the cost of some support for pumping and popping. And, of course, all of that with any suspension design can be tweaked a bit with a good suspension tune. And all of that can be semi-ruined with a bad suspension tune.

Edit to add: If you want to look at leverage ratios, the graphs for most bikes can be found here: http://linkagedesign.blogspot.com/

I would take most of those graphs with a grain of salt, particularly for short link bikes (VPP designs, DW link designs). But you can at least get a general idea of what different bikes look like. For whatever it's worth, the trend these days heavily favors going towards a simpler leverage ratio curve, similar to the Geometron HAB posted.

[HAB]

That last point on taking these with a grain of salt is a good one, especially for short link bikes (VPP, DW, etc). With those designs, small inaccuracies in selecting pivot points can make a pretty big difference in the result. Single pivots, or longer link 4 bar bikes should generally be more accurate.


And, fine, I guess people can have different preferences from me. I pretty strongly prefer more straight progressive leverage curves, but the stuff toast said about the tradeoffs isn't wrong.

[EWG]

That last point on taking these with a grain of salt is a good one, especially for short link bikes (VPP, DW, etc). With those designs, small inaccuracies in selecting pivot points can make a pretty big difference in the result. Single pivots, or longer link 4 bar bikes should generally be more accurate.


And, fine, I guess people can have different preferences from me. I pretty strongly prefer more straight progressive leverage curves, but the stuff toast said about the tradeoffs isn't wrong.

Right on. I'm on the other end of the spectrum. I've been riding VPP bikes for a long time, and I like the way they react, and it's predictable for me. But I'm not a straight up downhiller - I like going up tech steep stuff and I like going down fast, and I like flow, and the trails I ride support that (not that you linear guys don't, just talking about me.)

However, read Toast's really excellent explaination - VPP is especially sensitive to setting sag exactly "right" or at least, the same for each bike you ride, cause if you don't, the bike is going to react differently and you won't like it - and it won't feel intuitive. I play with my sag all the time, usually as an overreaction to when I ride poorly one day. Linear designs pretty much don't have those touchy issues.

If I switched designs I'd probably get used to it quickly, and maybe I'd love it, but I like the ability to mess with stuff when you are tuning sag, etc.

Now having said all that, Intense has changed the response curve. In the image below, their 2016 Tracer had the blue curve, and the newer T275c, which I ride, has the red curve. Much more linear. However, it still has some of those progressive characteristics which I like - but way closer to the linear stuff being talked about here. It's still VPP, kind of, but they tweaked it so much they don't even call it that anymore.

[HAB]

Santa Cruz is changing things up too. All the new lower link driven bikes are much more linear progressive.

[toast2266]

It's also worth noting that we're only talking about / looking at leverage curves here. But the anti rise and anti squat numbers are also going to have a fairly significant impact on how the suspension moves. Unless you take your chain and brakes off, in which case yeah, anti rise / squat curves don't matter.

[jm2e]

Thanks doods.
It explains why everyone I know who's had a short link bike has really struggled to dial in the shock. While I've been pretty happy on my Knollys (and other).

[HAB]

To be clear, those kinds of parabolic leverage curves aren't inherent traits of short link bikes. But they are how Santa Cruz and Intense, in particular, set up their trail bikes for a long, long time.

[Dantheman]

Heh: https://www.pinkbike.com/news/video-...rim-donut.html

[rideit]

Has anyone seen leverage curves from bikes we rode in the early oughts?
Like a giant AcS, an early Rocky Mountain Switch or Slayer, a Specialized enduro, or whatever else you can think of?
Ooh, I have one I would like to see, a Giant NRS!

[Andeh]

http://linkagedesign.blogspot.com/20...duro-2010.html
http://linkagedesign.blogspot.com/20...ayer-2011.html

Those are the earliest I can find. The LR for the Slayer is really good, would be perfectly fine on a 2020 bike. Antisquat is terrible though.

[EWG]

http://linkagedesign.blogspot.com/20...duro-2010.html
http://linkagedesign.blogspot.com/20...ayer-2011.html

Those are the earliest I can find. The LR for the Slayer is really good, would be perfectly fine on a 2020 bike. Antisquat is terrible though.

Yeah boy! And people wonder why VPP was such a big deal at the time...

[toast2266]

http://linkagedesign.blogspot.com/20...duro-2010.html
http://linkagedesign.blogspot.com/20...ayer-2011.html

Those are the earliest I can find. The LR for the Slayer is really good, would be perfectly fine on a 2020 bike. Antisquat is terrible though.

The Enduro actually looks pretty good too. It's antisquat numbers make sense in the context of a triple chainring drivetrain. And the leverage rate probably actually worked pretty well with the 2010 era air shocks. You can also see the comparison to a 2005 Enduro on the graph, which had a more linear progressive leverage curve. That '05 Enduro looks similar to a lot of bikes currently on the market (although they don't graph the antisquat in a gear that's comparable to modern 1x bikes).