First Look: ShockTune is a Free Suspension Setup App
Mountain bike suspension can be an intimidating thing to fiddle with, especially if your high-end fork or shock seems to have more dials than the space shuttle. Sure, you know your bike feels like crap over that one rough section of trail, but should you add more or less damping? And are we talking compression or rebound? And was it four clicks or four turns?
Ryland Lueders' free ShockTune app aims to solve the mystery of suspension setup using only your phone.
How ShockTune Works
The idea is straightforward enough: By mounting the phone solidly onto your handlebar or seat post, ShockTune uses its accelerometer to measure the forces acting on the bike. Picture yourself riding towards a big ol' rock with the ShockTune app running on your handlebar. When your front tire hits the rock, the phone's accelerometer picks up the impact because, well, it forces the entire bike upwards, no matter how good the suspension is. ShockTune displays that upward movement on a graph; the bigger the spike, the more (or faster) the bike was moved upward by the rock and vice versa.
The thinking here is that the less the bike is moved upward, the better its suspension must be at absorbing the impact. In other words, a smaller spike means a better bike.
What ShockTune Tells You
''There are really two key things to look for in the results graphs,'' Lueders told me when I asked him what all the red and green lines mean. ''First, as you mentioned, minimizing the number of spikes and oscillations.'' We've already talked about what the big spike tells you, but the oscillations are all the smaller spikes on the graph that come afterward. Let's go back to that same rock for this one. You're going to run straight into it again, only this time we're thinking about what happens after the initial impact is absorbed. Let's also pretend that your fork is, for some strange reason, running zero clicks of rebound damping; once the fork takes in the hit from the rock, it'll want to extend very quickly, so much so that it'll keep trying to do it, only to dip into its travel slightly and then extend again. And again. And maybe a bunch more times, too, even though the rock twenty-feet behind you.
Of course, depending on your level of sensitivity, this might be something you've felt before or maybe not, blissfully unaware of the blown damper in your eight-year-old fork. I'm sorta jealous, to be honest. Anyway, you generally want as little of that extending and dipping, AKA oscillations, as possible so that your suspension is ''quiet'' or ''controlled.''
The second thing you're looking for is minimizing the extremes, those big spikes on the graph that signify the bike being moved upwards excessively fast. Remember, a smaller spike means a better setup, and it goes in both directions. Lueders gave me an example of his fork using a bit too much rebound damping, which the graph showed as a large downward spike post-impact, as well as a larger upward spike but fewer oscillations.
''There are really two key things to look for in the results graphs,'' Lueders told me when I asked him what all the red and green lines mean. ''First, as you mentioned, minimizing the number of spikes and oscillations.'' We've already talked about what the big spike tells you, but the oscillations are all the smaller spikes on the graph that come afterward. Let's go back to that same rock for this one. You're going to run straight into it again, only this time we're thinking about what happens after the initial impact is absorbed. Let's also pretend that your fork is, for some strange reason, running zero clicks of rebound damping; once the fork takes in the hit from the rock, it'll want to extend very quickly, so much so that it'll keep trying to do it, only to dip into its travel slightly and then extend again. And again. And maybe a bunch more times, too, even though the rock twenty-feet behind you.
Of course, depending on your level of sensitivity, this might be something you've felt before or maybe not, blissfully unaware of the blown damper in your eight-year-old fork. I'm sorta jealous, to be honest. Anyway, you generally want as little of that extending and dipping, AKA oscillations, as possible so that your suspension is ''quiet'' or ''controlled.''
The second thing you're looking for is minimizing the extremes, those big spikes on the graph that signify the bike being moved upwards excessively fast. Remember, a smaller spike means a better setup, and it goes in both directions. Lueders gave me an example of his fork using a bit too much rebound damping, which the graph showed as a large downward spike post-impact, as well as a larger upward spike but fewer oscillations.
''This illustrates the tradeoff we make with excessive rebound damping,'' Lueders told me. ''That is to say, while the firmer rebound setting nearly eliminates oscillation, it comes at the cost of increased downward velocity after the bump and increased rebound velocity.''
One thing ShockTune won't do is tell you which way to turn the dials - you'll have to interpret that yourself - but Lueders said that the app is intended to help riders better understand what their bike is doing under them. ''I was actually increasing the rebound damping on my fork, trying to reduce the rebound pop I was feeling,'' he said of the experiment above. ''But, in my case, I had actually added too much rebound damping and it started to have the opposite effect of what I intended.''
If you're wanting the deep-dive on ShockTune, you can check out Lueders' explainer here.
Sounds neato, right? For sure, but there are a few other things to mention, the most notable being that ShockTune is something you use in a controlled environment, not at any point during the ride. Because it's using the accelerometer inside your phone, you have to attach the phone solidly to your bike, but obviously not any of the moving suspension components. If you're evaluating your fork, you'd probably mount it to your handlebar; the shock, you'd attach it to your seat post.
The phone must also be mounted ''perpendicular to one of the axes,'' which is a fancy way of saying get it straight or flat. Once you press record, the accelerometer will also measure everything it feels, and it will definitely feel you pedaling squares as you sprint towards that rock again. Because of this, you'd want to focus on a single, short section of trail, and try to be as consistent with your speed, line, and body inputs as possible. And the more samples you take, the clearer the picture will be. You can also combine and average your recordings by clicking one button.
Does it Work?
After farting around with mounts and rubber bands that wouldn't keep the phone from shaking when I hit a bump, I made my own solid mount using some reflector pieces, SRAM shifter hardware, and an old Topeak cellphone case that now has an extra speed hole. I used a spirit level to ensure that the phone was as flat as possible, with the homemade mount allowing for angle adjustments to get it just right on every axes. The phone was attached to the Mondraker F-Podium DC's handlebar with RockShox's new SID Ultimate on the front of it, and my artificial bump was as high-tech as it gets: I found a 2x4 in the neighbor's yard and laid it on the road.
First up was running straight into it with the fork unlocked and the ShockTune app recording, and I saw the results as soon as I pressed the stop button: A green spike. Next up, I locked the SID out and rode straight into the 2x4 at roughly the same speed as when the fork was unlocked, only this time the spike was much, much taller because the suspension was too firm. With the fork effectively not able to move, the phone's accelerometer was displaced quicker and more than when the fork was unlocked, which showed itself as an even larger green spike.
I could produce a similar effect using too much rebound damping, too, only inverted on the graph. While ShockTune has some limitations in that the phone needs to be level and the intended impact in near-isolation, the completely free-of-charge app provides some interesting data for those curious about what's happening under them.
After farting around with mounts and rubber bands that wouldn't keep the phone from shaking when I hit a bump, I made my own solid mount using some reflector pieces, SRAM shifter hardware, and an old Topeak cellphone case that now has an extra speed hole. I used a spirit level to ensure that the phone was as flat as possible, with the homemade mount allowing for angle adjustments to get it just right on every axes. The phone was attached to the Mondraker F-Podium DC's handlebar with RockShox's new SID Ultimate on the front of it, and my artificial bump was as high-tech as it gets: I found a 2x4 in the neighbor's yard and laid it on the road.
First up was running straight into it with the fork unlocked and the ShockTune app recording, and I saw the results as soon as I pressed the stop button: A green spike. Next up, I locked the SID out and rode straight into the 2x4 at roughly the same speed as when the fork was unlocked, only this time the spike was much, much taller because the suspension was too firm. With the fork effectively not able to move, the phone's accelerometer was displaced quicker and more than when the fork was unlocked, which showed itself as an even larger green spike.
I could produce a similar effect using too much rebound damping, too, only inverted on the graph. While ShockTune has some limitations in that the phone needs to be level and the intended impact in near-isolation, the completely free-of-charge app provides some interesting data for those curious about what's happening under them.
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Wait, is there a leader board?
Imagine being able to set your saddle and stem straight in a blink. Also, the polygonal section would increase strength in the desired direction.
I just had an idea though, flats on the sides of the fork, then you have two screws, one on either side of the stem to “set” and center the stem (I.e 180 deg apart). Then you tighten your stem pinch bolts to torque, and unscrew the stem centering screws. Voila, a centered stem with the traditional breakaway method of our friend, Mr Friction. Patent pending
A simple adjustable adjustable jig is all you need. Could even be a really small laser, low power. You're only using laser ablation on the surface layer. Set it in the jig, push the go button, would take less than 15 seconds to make the appropriate mark.
The elephant in the room is how hard are the short stems we got used to spec in our bikes to align with the front wheel. But as @krashDH85 has elegantly proposed, a simple jig and a low power laser would do wonders for us mere mortals working in our bikes at home.
I agree that dual crown forks are a good solution to the problem, and would love to have one on a all mountain bike, its just getting matching suspension performance and geometry thats the main problem to me, also weight and lack of on the fly travel adjust are other downsides.
I like your idea of hex steer tubes or something, but then everyone would need a special type of stem, which there would be mass balking about. i truly believe that would be a bummer to not be able to use all the stems that we all have.
Without going too technical, we *could* have a way of running our actual stems with my idea of polygonal steerers. Since the conforming/shaping of the steerer would mean its effective diameter would be less than 28.6mm, we could run an adapter shim, consisting of six semi-circular sections, which would bring the actual steerer diameter to 1-⅛. Once you are ready to jump shark and buy a new HexHead™ (see what I did there?) stem/headset, you'd simply take off the adapter shim and mount the new components to your HedHead™ equipped fork.
Or The Industry™ could simple etch a couple marks on the last 10-15 cm of the steerer tube and we could call the day off :-P.
Moral of the story: There will be some amount of play no matter how you look at it, and that will translate to the end of the bars, and the stem won't be aligned correctly. And if that alignment is off on the steertube to the axle, there'd be no way of re-aligning short of pressing the steer tube out and back in again
If you know your suspension is setup wrong then you can tell whats wrong with it and adjust it to feel better.
Even if this app does actually provide useful data (which i'm pretty sure it wont because there are way too many variables involved) it would still be useless.
If you know your suspension is setup wrong, but don't know how to fix it, this app might give you some insight into the issues at hand.
Another person that thinks a Smart phone will be the answer.
Watch a Dialed episode Jordi explains in plain English how to go about setup.
All manufacturers have a base line set up to start with and suggestions from there.
No smart phone no torpedo level.
At the end of the day, the race team kept the guy who complained and cut the guy who just kept going faster. Why? In the end, the team wanted a driver that could help them improve the car to make the car faster. They knew that even the fastest driver wouldn't be able to drive a insufficiently setup car fast enough in a race.
I think it was from the book "Go Like Hell," great book.
Anyways, your comment is pretty spot on. I have friends who bought bikes and have NEVER even checked sag. In their eyes, as long as it moves when you run into something, it's working.
Besides that taking one impact at a time isn't how it works in real riding. Sure this might help you dial in your rebound to get closer to critically damped, but so can riding off a curb and tuning the clickers to reduce oscillation. Depending on riding style and trails this may not be ideal. Maybe you want less rebound damping to slam that wheel back down for traction in rough corners. Maybe you need to speed it up because you ride the fork and it's packing down because too much damping isn't letting it extend fast enough before the next impact. (Btw, most people probably need faster rebound. We don't just ride off curbs in the trails, so who cares if it oscillates once or twice off a curb?)
Regarding the mounting: Why should it be mounted perpendicular, and perpendicular to what? The images seem to indicate perpendicular to the ground, except impacts aren't perpendicular, and suspension movement isn't perpendicular.
I did the recommend thing and took out spacers when I fitted the megneg, with the aim of firming up the mid-stroke. Mid-stroke is better, but the o-ring pretty much falls off the bottom of the shock still. There's obviously a window of sag, so that is an option, though it can get harsh. And I thought the HSC circuit was still affected by the LSC knob. Suppose it depends on the individual shock. But, yes, the plan was to put one of the spacers back in.
HSC is affected by LSC in that HSC won't be used until the oil can't flow through the LSC. So leaving LSC wide open means it will take more shaft speed to use the HS circuit, but a bottoming event is pretty much always going to be a high (maybe mid) speed event, so even a wide open LS circuit will be overwhelmed and the HS circuit will be controlling the hit. The only way LSC could help prevent bottoming is if the spring rate is a little bit low and LSC is helping to counter (some) of a rearward weight shift, so when that big hit comes the shock has a little more travel left. But that's a band-aid, and spring rate really should be the thing deciding ride height.
Giving raw data means nothing if the data is drawn from an inherently flawed sensor. Sure, maybe the shockwiz also isn't the greatest tool. But if your riding is at the point at which you want suspension analysis, you should just shell out for the Motion IQ kit.
I'm "donating" my opinion on the matter because my job is to work on the bikes of jerk-offs like you.
mtbx.bike/assets/images/shock_tune/ExpandAvgVel-halfres.png
mtbx.bike/assets/images/shock_tune/ExpandAvg-halfres.png
The first and most obvious issue is the mount - it's impossible to get it aligned (aligned to what is another question, I can think of various reasons to align it to different parts of the bicycle depending on suspension geometry and your tuning goals). If that position was somehow known and universal among all MTBs, the app would need some kind of internal calibration that takes averages of values at high speed and low yaw to determine what relation it is mounted in, because it's impossible for a human to figure that out especially Mike Levy with some old Topeak mounts and a rubber band.
The other thing I wonder about is filtering and data rates. Every phone model is going to have different IMUs, and board design and OS both will affect how the acceleration data travels and can be consumed by apps. The app would have to know this and apply some kind of filtering so the data is equivalent between different phones and OS.
Lastly is how do you tune the filtering in general - even purpose built equipment mounted properly and calibrated in a vehicle creates lots of noise for various reasons, a mountain bike will create absurd amounts of noise. On that graph, the time access doesn't seem to even have time labeled, and those spikes are meaningless to interpret without knowing their duration. A 60 m/s^2 spike over .01 seconds is completely different than one over .05 seconds. Haha! Actually, I just wrote all this to humble brag about being an engineer on pinkbike, but it was a trick, I'm actually a neurosurgeon that watches youtube videos about IMUs, oldest trick in the book, can't believe you read this wall of text. Happy tuning.
And you nailed the other part. If you care just a little bit and spend a little time, anyone can feel the extremes, and then bracket your tuning to get to something that feels better.
One smart thing this company could do is have the users of this app opt in to sharing their data, so they could collect large amounts of traces with the phone type and hopefully bike info labelled, get some idea of what is "normal," adjust the filtering on certain phones that need it, and try to set meaningful baselines. This still has the problem with the mounts being inconsistent, different bikes having different geo, stiffness, vibration characteristics, etc.
Going for the cheap shock just because you're afraid of dials would be like buying a stove with an on-off switch instead of a dial because you're not a chef. Sure it "cooks" food, but the experience of eating most of that burned food will be shit. Same with buying a shock without adjustability. It moves, but is just aimed at fitting the average person, so if you're outside that range of average (size, ride style, trails, f*cking tire pressure), that shock is going to burn you and the ride will be (relatively) shit.
If you can afford it, get the better damper, and spend a tiny bit of time tuning it. Your rides will thank you.
1. Jerry rig my $500 to $1000 phone to my handle bar, expose it to shaking and impacts it was not designed to handle, and risk breaking said phone for marginally useful data?
Or
2. Buy or rent a Shockwiz which actually does work and provide useful suggestions?
Or
3. Just ride and try, asking friends and bike shop folks for advice?
Definitely number 3
Possibly number 2
Absolutely not for number 1. Free is nice, but the risk reqard here is not worth it.
The only thing someone external can tell you is that if you're bottoming out a lot then you need to reduce volume in the air spring (or increase spring rate on a coil. There is actually more to each of those, but then we get next level)
All that said, I recently removed the garmin mount from my mtb (still on my commuter, for exploring new routes to work), and just use my watch for tracking and osmand (or opencyclemap) on my phone in my pocket to double check trail maps
With offline maps and no need for a data connection (or any connection at all for that matter), the battery life is no worse than with the Garmin.
It's a free app. It uses a phone on whatever homebrew mount you put it on. It provides limited data that is RELATIVE, very important here-- RELATIVE INFORMATION. Make setup changes and see the data change. Use your brain and decide if it's helping or not. If it's not, uninstall the app, and continue riding.
"oH a PhOnE isNt AcCuRaTe FoR rEaDiNgs" calm the f*ck down, ya nerds, it's a tool that has an inherently limited use, but it's also free and nearly no hassle to use, and even easier not to. Beats the wee out of spending thousands on power meters and shock sensors. Sheesh
The app author's insistence at trying to accurately align the device shows they're missing some of the understanding: you could mount it any way at all, even upside down and aligned to your father-in-law's 65 degree rise hybrid stem, and just tell the software to treat that alignment as the "zero".
Seems like the biggest challenge is getting the phone mounted correctly to your bike for this to work, so why not get rid of that and replace it with an easier solution?
actually that's not true. I know how to set my sag correctly and once I have that set i like to slow the rebound down a bit and also adjust the compression so it's on the soft side. then I just leave it like that and don't f*ck with it. I seriously couldn't imagine adding a phone to the mix with even more data to absorb.
“1% discount on new phone purchase when you turn in your old phone run over by a bike and smashed on the rocks”