The Tuesday Tune Ep 16: Bump Compliance and Harshness

Mar 1, 2017
by Vorsprung Suspension  
Views: 5,276    Faves: 29    Comments: 2


For better or worse, Vorsprung's location in Whistler gives us exposure to some of the harshest, most violent conditions bikes ever see. From A-line's infamous braking bumps (that the trail crew, fortunately, iron out a few times a year!) to the sheer brutality of In Deep, there are plenty of reasons why many riders here end up feeling like their hands are broken after a few days of riding.

Consequently, one of the biggest issues we deal with on a day to day basis is minimizing ride harshness. To achieve this, it is necessary to understand the physics behind bump absorption, which is what we are delving into on this week's Tuesday Tune. Rather than simply handing you a set of instructions saying "reduce X, increase Y, set Z to extra medium", we're presenting an introduction to the fundamental ways in which your suspension responds to encountering a bump. We hope that by doing this, that you can relate this to your own adjustments and find yourself making more productive changes when you are adjusting your setup.

This week's video is pretty heavy in theory, and it does assume that you are familiar with the basic functions of a spring and a damper (if you aren't, check out our video on the functions of springs and dampers).

As usual, this is just the tip of the iceberg when it comes to in-depth analysis, and should not be considered anything like a comprehensive explanation of everything to do with a smooth ride. Many factors not directly related to your mechanical suspension can influence the perception of harshness (and hand pain), including rider variables such as strength, fitness and fatigue levels, as well as cockpit setup and brake configuration. Tyre pressure is invariably part of the equation, and should always be the first thing to check when something feels exceedingly rough. It's also worth noting that your priorities for suspension setup may not be the same as the next rider - some people want the smoothest ride possible, some people want the fastest thing they can hold on to on steep terrain, most people lie somewhere in between. Setup is all about finding the compromises that work best for you.



MENTIONS: @VorsprungSuspension



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38 Comments
  • 9 0
 Hey Steve, just wondered if you had any insight into the effect of head angle on people's perception of harshness. As you touch on, a slacker head angle should, in theory, cause the fork to flex and bind more on flat landings, due to a greater transverse force; but conversely, it should bind less on square edge hits where the force is more rearwards. Have you any experience with experimenting with head angles? @VorsprungSuspension
  • 30 0
 In practical terms, very slack HAs can definitely hinder small bump performance a bit, where the angle of incidence (where bump contacts wheel OD) is not a long way from vertical. Big single hits (landings etc) tend to generate enough force with enough preparation time for the rider to brace for (and/or absorb) the impact, and so they don't tend to be so noticeable compared to repeated corrugations or small square edges. The current crop of slack head angles actually line up the fork fairly closely to about the maximum bump size you can realistically run the front wheel into without eating a bag of dicks, but I think that's more of a geometric coincidence than anything.
  • 12 0
 @VorsprungSuspension: "...the maximum bump size you can realistically run the front wheel into without eating a bag of dicks." Well put good sir Wink
  • 9 0
 Tuesday Tune time = Best part of my week*

*Not counting when i'm actually riding my bike, obviously.
  • 4 0
 I've been following some ShockWiz threads, and find that device even that isn't "army-proof" enough to get an average Joe's suspension dialed. I'm convinced that knowing the basics of how suspension works is the best way to clear up all the mystery, confusion, and even blatant misinformation out there.

I'll chime in with the others and express my gratitude to you, Steve @VorsprungSuspension, for getting accurate knowledge on suspension into the generalpublic. I can say that I might be seeing signs of it working, since I've been running into a lot more people who know what they're talking about when it comes to suspension setup.
  • 7 0
 best nerd video series ever. the geek king! awesome stuff.
  • 2 0
 yes, I would definitely decrease LSC according to chassis stability in your preferred terrain, and probably you can get away with lower HSC as well. I think too many riders have too little LSC to such an extend that all flow goes here and HSC end up doing nothing..
  • 1 0
 You mean too much LSC?
  • 3 1
 hi, i would appreciate some deeper explanation on hsc and lsc in terms of it use (please not something like hsc is for high speed impact) i´ve been struggeling with a rockshox lyrics, so far works horrible, im very sure it comes short with the oil.
  • 2 0
 How much would be helpful to you?
m.pinkbike.com/video/460892
  • 2 0
 try less psi + more tokens and wee bit slower rebound
  • 1 0
 @mae-fr check the video @kanasasa linked to, we covered that in some depth Smile
  • 1 0
 @kanasasa: thankyou very much guys!
  • 1 0
 @trauty: I will try that, hopefully doesn´t get to be too progressive, thanks!
  • 1 0
 @mae-fr:

I'm 170-175lbs and run my lyrik with 3 tokens at about 75psi. Used to run at 80-90psi and it was a bit harsh.

Tokens are 100% necessary to unlock the potential of the pike / lyrik

Note that I ride aggressively and most of my local trails are feature driven
  • 1 0
 @nvranka: 3 tokens!? I thought 2 would be more than enough, I would have to try with 2 first, then see if I can get a third one to test it and see how it varies. Im about the same weight 5,11 with similar description to the riding style. I hope the tokens can be the solution
  • 1 0
 @mae-fr: yeah man...try two, but don't be afraid to put a third in...it isn't insanely progressive, mostly late stroke

not that it matters, but ran into Curtis Keene locally and he was running 3 tokens at 90-95psi, and wasn't riding race pace or anything (was a pace I could keep up with...he was cruising)
  • 1 0
 lyrik 170 mm 28% sag , 3 tokens , 10 lsc ( from fully open)
  • 2 0
 So for successive bumps, faster rebound is obviously good. Letting the spring return to a mellower part of the suspension curve/lower spring position/lower spring force allows lower breakaway force for the next bump. So what's the trade-off for super fast rebound? (Assuming it's not so fast you're getting bucked off the bike) I'm guessing it means less stability and control in lower speed or smoother terrain, but how much does that matter? Shouldn't we be running super fast rebound if we're going to be smashing rocks and roots?
  • 1 0
 I think the bottleneck for how fast you can run your rebound is on jump faces/g -outs. If I ride choppy terrain ( rocks,roots, braking bumps) I speed up the rebound another 1-2 clicks but then the bike is a bit unpredictable on jump faces.( not getting bucked but a bit inconsistent) For riding a trail with a mix of choppy and larger jumps, then you have to compromise and run a click or 2 slower.

Also if I ride in the wet, I usually slow down the rebound a click or two, I find more traction that way
  • 1 0
 There comes a point at which the stability tradeoff becomes pretty substantial even on fast rough terrain, meaning that due to rebound overshoot, the bike starts getting bounced around a bit and stops being planted and tracking the ground. Rebound that is too fast can actually reduce traction in that way.
  • 4 0
 @VorsprungSuspension: So rebound speed can basically be set by "turn the knob until it feels scary to ride, then back it off a click or two?"
  • 3 0
 Hmmmm I feel like he just scratched the surface here. Obviously an in depth topic. Would love to sit and pick hisbrain over a couple of brews. I love this stuff.
  • 3 0
 Textbooks have been written on less, for sure. What we are trying to do here is provoke logical thought about the way that suspension functions, to help elevate riders' understanding of it on a conceptual level. It is a complicated field to *fully* analyse, absolutely - but understanding some of the underlying principles even on a basic level means people are less reliant on taking someone else's word for it when it comes to setup, performance expectations etc.
  • 3 0
 @VorsprungSuspension: it's working man, I've watched all your videos (some multiple times) and like other posters, feel like I am starting to have a somewhat functional level of knowledge in how to set things up. Thank for you sharing this knowledge in layman terms with the community, very valuable.

My new trail bike is coming with a Pike, will see how it rides but I predict a Luftkappe being fitted when it's time for first servicing.
  • 1 0
 Quick suspension question unrelated to the video; is a 400 x 3.2 coil equivalent to a 369 x 3.0 when on a shock with a 3 inch stroke. I'm operating under the assumption that coils are linear and that if it takes 400lbs to go 3.2 inches then it should take slightly less to go 3.0, and (3.0/3.2)400=369
  • 2 0
 @kleinblake the 400 part refers to pounds per inch, not pounds required to fully bottom out, so irrespective of stroke length it will be stiffer than a 369. 3.2 in that case refers to the free stroke of a spring that is designed for a 3.0 stroke damper, whereas the 3.0 is a nominal measurement also for use on a 3.0 stroke damper. Yes, it's confusing.
  • 1 0
 I kinda understand this, the only issue is I have a boxxer team and a vivid r2c I like coil more and blah blah blah...a LSC and LSR isn't very tunable I can change how my bike feels in g-outs and making it so that dosnt pack up but that's all I can do...any suggestions on how to get a better tune with minimal money spent.
  • 2 0
 So in theory if i we're to change my spring rate from 450 to 500 my L.S and H.S dampers would have to be LOWER
By a few clicks......is that correct?
  • 6 0
 I think the answer would be "it depends." Assuming you need the higher spring rate and you are overdamped to compensate, then most likely you could go with less. And you would probably want MORE rebound damping. But, it could be that you could leave it the same or increase the damping due to the higher spring rate. Kinda depends on where you are starting from.
  • 3 0
 @TenBeers: very much agree with your synopsis there, clearly you're thinking this stuff through!
  • 1 0
 @TenBeers: thanks bro.
  • 5 0
 @VorsprungSuspension: It's all based on information I get from your awesome series, keep it up! This last one was great, and I am finally reaching a point where I feel confident in setting up my suspension properly. I actually had a zen moment a few weeks ago traversing a fast, rough section where it felt like neither my hands nor feet were moving up and down, suspension soaking things up perfectly. Then I lowered my front spring rate before my last ride, just slightly, and screwed it all up, felt like garbage. Temp changes between the 20's F to 60's F don't help either.
  • 4 0
 Very nice videoseries! Keep em coming.
  • 3 0
 Man, I just love the knowledge Vorsprung is dropping on us so regularly. Thank you @VorsprungSuspension!
  • 3 0
 Hurray, the best video of the week.
  • 2 0
 This guy is deadset suspension Einstein
  • 2 0
 Useful, thanks!







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