Rebound speed vs Suspension performance (MTB Ep.15)

Hello! In this episode it will be discussed in deep detail what is the effect of rebound speed on the suspension performance, in particular, on the transmissibility of the suspension.
MUST WATCH: How to correctly setup rebound damping (Ep.5)
• How to CORRECTLY setup...
Aditional info: Telemetry data of Curb test
• FREE Suspension Data A...
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[@mythbuster204]

Wow first time I see someone in the biking community who is not talking gibberish from a subjective perspective but actually understands the physics, nice work :)

[@andrextr]

Matko Pečanić thank you my friend!

[@andrextr]

Thank you all for the HUGE positive feedback, it means a lot for me! Bye :)

[@buffalotheory504]

Hi +andrextr I learnt more about MTB suspension from your channel and on pinkbike than anywhere else! Could you explain how I can find the 3 usable rebound damping settings on my RS Pike fork? There is a video on the rear but the front is the same process or different?

[@afnanabdusamed3100]

can u suggest any good books that details about suspension.

[@aaron00hurst]

I learned more from this video that i did from some of my $1000, 4 month long college math classes required for my math minor. You sir are a hero.

[@andrextr]

:D eheh thanks

[@Raumance]

Andre you are the fucking champ.

[@MtbEnduroChile]

You are right buddy! One of your very best videos! Cheers from Chile!!

[@andrextr]

Gracias my friend! Un saludo!

[@smunoz08]

Grande German

[@DaStuntChannel]

German geenioo

[@northeastmtb1575]

Awesome video, I spent almost 2 years tuning my rockshox rear shock, and eventually ended up on the second lowest rebound setting (with very high air pressure), now I know why!

[@az220584]

Your explanation is truly amazing and easy to understand..i was laughed myself when you the quote statement "What the Hell is happening"...Tks

[@RGCastro7]

Great job, Andrextr! Thank you for sharing this with us.

[@joakinhox00]

Amazing men!! Best video I've seen in a long time! Already shared!!

[@zinkws]

Nice video. Great explanation. Good work.

[@davewalsh8278]

a complicated subject made simple. Well done Andre

[@phfreire95]

Keep up the good work man, that was great.

[@robinlamontagne7026]

Really good explanations thank you for all the good work you are putting in your videos!

[@torabora851]

Awesome! Very clear idea how to think about rebound. Now I understood what highspeed recovery of my DBCouil needs for. Thank you!

[@joubercorlaitic.nascimento9706]

I dont have words for you man!!!!! Great video, thanks

[@alissonkrynski6482]

Amazing! Excellent video! Thank you!

[@EeroSoralahti]

Truly excellent video! Topic, animation, explanation... everything! How come no bike magazine or review site has not hijacked you yet, even as a freelancer? Your videos put the qualitative, vague and descriptive comparisons the traditional bike media produces to a shame... Well done mate, and keep it up!

[@andrextr]

Thank you for your very nice words!! Since I'm unemployed rigth now I'm fully available for that job if any mag is interested to hijack me eheh :D

[@goncarrasco]

Tuning shocks and forks nowadays can be complicated. Your video makes things very understandable. Very good work Andre!

[@andrextr]

+Gonzalo Carrasco thanks Gonzalo :)

[@federicotaddei4197]

Absolutely clear, an example how to show suspension settings ! Thank you very much for your excellent work!

[@jackschreuder5657]

Another fantastic video which again caused me to tune my suspension again every time i watch one of these videoos the next time i go riding my bike feels better XD

[@Lohman1464]

Great job! really well explained!

[@akinnon2000]

Even better than what io was looking for thanks ! Very well done.

[@carlosgil697]

What a masterclass!! Great video and so interesting and useful concepts.

[@andrextr]

Thank you (obrigado) Carlos!

[@Ordinarysortaguy]

Amazing video, my shock has rapid recovery so to know this is a game changer!

[@bikekona06]

Your videos = the best videos about suspension !

[@andrextr]

Thank you !!! :D

[@dakshalpatel3858]

Most practical way to teach Suspension(Vibration) topics of Physics..Cheers!!

[@SnakeC666]

Excellent series, so much great information!

[@andrextr]

Thanks!

[@arniegv]

Very good and simplified graphics explanation...You're the best Andre! I love your channel! Thank you so much for helping us out.

[@andrextr]

Thank for your words Arnie :)

[@santiagorueda5200]

Nice and easy explanation, fantastic Job!!

[@andrextr]

+santiago rueda thanks :)

[@edmo1982]

Man! Stoked by your videos. Congratulations. great and correct explanation

[@andrextr]

Thanks. :)

[@basiek1410]

super explained, I was looking for it for so long, sorry for my English :)

Great analysis and job. Far better than the vague tutorials and suspension tuning tips from most of the "specialized" biking media. Thanks a lot.

[@juscelinocastro]

Aproveito para parabenizar o belo trabalho de seus vídeos. Fantásticos!! Excelentes!

[@andrextr]

Obrigado :)

[@lukefarmer5391]

excellent video. I subscribed because it was so good.

[@kikoyouth]

Excelente trabalho André! Explicações muito claras, principalmente tendo em conta os detalhes de teoria de vibrações e ruído. Well done :)

[@andrextr]

Obrigado! Abraço :)

[@omarfernandez6943]

Fantastico, you're the best!!!! I appreciate your work Regards From CHILE!!

[@andrextr]

Muchas gracias!! Un saludo de Portugal

[@jmkulikowski]

Excellent, as always!

[@andrextr]

Thanks! :D

[@jc291288]

great, so clear like every video you made. I will love RS's rapid recovery, I was in doubt but after this video I totally diceded to try it.

[@andrextr]

Thanks again Jean Carlo for your support :) Fox also have a "Rapid recovery" but their marketing department didn't remember to call the high-speed rebound in such a fancy way (which sells) :D

[@tomalbert3299]

I watched all your episodes. My understanding of suspension and kinematics increased a lot! Would be great to see new videos in future.

[@andrextr]

Thank you Tom! I already done another video to be published very soon with VitalMTB ;) But yes, unfortunately I don't have much free time now for doing videos.

[@MTNcorps]

This is an excellent fundamental video on dampening and your graphics were excellent. Well done sir.

[@andrextr]

Thanks! :)

[@TheYunok47]

Great videos bro!

[@andrearicci4707]

Great Andre

[@aynalineo]

That was great man! Waiting for the nex t videos

[@Bigsbeee]

Enjoyed very much .

[@benjamimnande442]

Excelente explicação!

[@osvaldovegacasanova3559]

awesome work!

[@ashbridgeprojects6916]

Excellent video, I've been educated.

[@ryanmartin6878]

Great video!

[@CrissGoes]

What a great video.

[@maxlaguda4232]

Ahhhhhhh, now I know why suspension companies make a low speed and high speed rebound adjustment, thanks, keep it up

[@rodrigozepeda3525]

Te la rifas carnal, muy buenos videos !! sigue asi =)

[@CaptainCrunch99]

Most excellent !

[@Seldoff]

This is gold!

[@gia_minh_]

really helpful! thank you!

[@R1pp3d]

Awesome video :) It would be cool if you could make a video about forks sometime, especially regarding how to balance compression damping and spring rate (and spring curve too as we can adjust it easily in air forks). I have a pretty good understanding of how the damper works but actually applying it and getting a good setup is more difficult

[@civilstructural]

this is way better explanation than all of your videos, with proper physics theory and application, the type of explanation I'm looking from you videos.

[@andrextr]

Thank you. I also agree with you, but this one took me lots of hours to prepare.... but it was worth it :) Bye

[@mayconcoelho7415]

Very nice!

[@patrickfiore7067]

I’m a math teacher (and mtb shredder), and I really enjoyed the thorough breakdown of the natural frequencies! I love for a solid explanation, which is why I teach lol, and this vid nailed a topic that is so elusive. Great job my friend! Home run!!!

[@andrextr]

Thank you Patrick !! :)

[@esgarrapa1]

Good job.

[@c0rky0001]

Epic!

[@vigneshkannak2133]

This is the best video I have seen related to suspension tuning. Super clear. Can you please share the algodoo file?

[@2prycey]

Loving your videos, it would be great if you did a video on the science behind different wheel sizes and the effect on suspension?

[@andrextr]

Thanks! I have this super scientific picture (eheheh): ep1.pinkbike.org/p5pb14377433/p5pb14377433.jpg I never dig into the wheel topic, but I would say that bigger wheels decrease a bit the suspension shaft velocities and bump frequencies (making the bumps smoother, as shown in the picture). Bigger wheels also increase the center of mass and add rotational mass. More importantly, if you do shuttles on a van, it's harder to put the bike inside (eheh). So it's always a trade off. Bye

[@MarcoAurelio-sh6bp]

Eslovaco, não consigo parar de rir! Você entende bastante! Dá uma força pro Brasil!

[@andrextr]

Foi muito boa essa do eslovaco kkkk

[@MarcoAurelio-sh6bp]

andrextr Melhor de tudo foi a surpresa inimaginável que você trouxe dizendo ser Português. O Henrique é muito bem cotado por aqui, mas você pelo que vi é além de muito conhecimento técnico atencioso. Foi um prazer. Saúde e sucesso pra você! Abraço.

[@wigdig]

really enjoying your videos, thank you for making them. do you think you might look at fork setup in more detail? I've always wondered how volume spacers impact forks like the pike

[@andrextr]

+wigdig Check my video about air spring shocks, it talks about volume spacers. Although it's about shocks it can be applied to forks since the air spring has the same principle. The volume spacers affect the second half of the travel, making it more progressive and firmer at the end of the travel. Good to absorb bigger impacts. If you experience many harsh bottom outs use more spacers. Otherwise it's OK as it is (the idea is always to use full travel but without many harsh bottom outs). Bye

[@hermessamirherrera1887]

Great videos Andre! Is it possible to make a video to compare/understand the variations of the different geometries and travel distances (DH, enduro, trail and XC) on the same difficult track? And also to understand how the suspension travel potencializes the human bump absortion. For many people seem obvous, more travel equals better descent, but I have heard that "the biggest suspension travel is in your arms and legs" so, how does this apply overall? Best regards and thank you for your clever videos!

[@winters3]

perfect :)

[@moviepassion7995]

Really interesting and really well explained!! Where do you have all this knowledge from?

[@Raumance]

He takes the torn tires of the local children, melts them and then he drinks it.

[@andrextr]

Eheh. This is a hobby, I always liked suspensions since a little kid, so I've been bulding this info along many years :) My science background helps on this :)

[@moviepassion7995]

Eheh. That is a nice hobby :D

[@Oliveiraa1606]

Muito bom

[@mithrandirtheistari]

Hey Andre, awesome stuff on your videos! So let me ask something, if I understood correctly, if your shock has separate LSR and HSR knobs, the HSR should be set FASTER (less damping) than the LSR knob?

[@andrextr]

Hi. Yes, low speed rebound needs to be slower than the high-speed (but this does not necessarily corresponds to the number of clicks of the settings!!!). And don't use extreme settings because high and low-speed rebound work together (for instance, in a high-speed rebound event, although the oil flows in the high-speed circuit, some of the oil also flows through the low circuit). If you have a shock with both settings I would recommend to watch this video at minute 9:00 ( kzbin.info/www/bejne/j5vUnWShet2peac ). Probably this is not the best way to tune it, but I believe it's a good starting point, at lest it's a balanced way to do it, without going into the extreme settings. If you want to try it tell me if it worked well for you.

[@heinrichhirsch4242]

Realy nice Video ans good explained. What have you used for Simulation?

[@andrextr]

A free software called algodoo 😆

[@rea50]

Subbed

[@alessandroamendola5140]

Great work man! Which software are you using?

[@andrextr]

+Alessandro Dando For the simulations I used algodoo. It's a free tool, it's not great but it works OK with simpler simulations like the ones of the video :)

[@MW-ud8zp]

Did you learn about this by yourself or in college? Really informative video. Good job. Also: are the physics simulated in Phun?

[@andrextr]

Maciek Waligorski By myself and using Google eheh ;) my background is biology related. yes it was on phun. not great software but it works ok with simple stuff

[@Andr3ground]

André!! meu chará, muito bacana os videos! Que software vc usa para todas essas simulações!

[@andrextr]

+André Rios Usei o algodoo. Não é muito bom, mas funciona para coisas simples. Valeu!

[@DoubleClutchProductions]

What software are you using to simulate these, really like your info thank you.

[@andrextr]

Algodoo (free)… or working model 2D

[@matthewshultz8762]

Can you do a video on how to set up a fork for critical rebound similar to ep. 5 with the shock for those of us with hardtails? These videos are awesome and really help me understand some of the finer nuances of suspension workings.

[@andrextr]

Thank you. This is a very requested question but unfortunately I don't have any good "scientific" method for the fork rebound. On a full sus bike my advice is to setup shock first and then tune the fork in a way that feels balanced with the rear (or even a bit faster). For an hardtail you don't have that reference point. My advice is to tune it by "feeling" (i hate feelings :D), in such a way that the fork won't behave as a pogo stick or too slow. The good news is that you have more room to error with the fork rebound, since contrary to the shock, a quite faster setup will not send you over the bars on sketchy trail or jump.

[@ionitacosmin6190]

The same explanation for compression. Compression speed vs suspension performance!

[@izaq_douraku]

really interesting and awesome explained... 😂 did you make bike simulations in PHUN? im sorry BAD English...

[@andrextr]

Yes it was in Algodoo. It's not very good, but for simple simulations like those on the video it works OK.

[@izaq_douraku]

andrextr thanks! i would recommend your good video to friends! bye🤗

[@RoboticusMusic]

What do you think of the DVO Emerald and RockShox R2C rear? Are they the best suspension? I'm asking for a downhill ebike build. I won't be pedaling much so I just need the best possible suspension for this application.

[@SGMTB]

Great explanation, thank you! Unrelated, but something I'm curious about: Is a more progressive air spring superior to more damping of high speed compression? Because HSC is meant to slow the shock down in essence when it encounters high speed hits. However, wouldn't it be better to simply pop in another volume spacer instead? Or are these achieving the same thing, simply in different increments?

[@andrextr]

Thank you! Yes, in my opinion is better to add a volume spacer and use the low as possible high-speed compression (HSC). Because HSC does not only kicks in on big impacts, it also kicks-in on high-frequency small bumps like going fast over rocks, pot holes and roots. So, HSC is nice to avoid harsh bottom-outs but it also produces harshness over those small bumps. With a volume spacer you increase the final progressivity without reducing the small-bump compliance. (I discussed this topic on Ep.7 video). Bye

[@SGMTB]

Awesome thank you!

[@adamdonaldson7409]

Great Video Andre! Question, does the RockShox Pike and Monarch Debonair come with High-speed rebound damping, and for a 60kg rider what would be a good Low-speed damping for the fork? Thanks

[@andrextr]

Yes, rockshox called it "Rapid Recovery". It's just a fancy name for high-speed rebound (marketing). Pike and Monarch have the "rapid recovery" thing. In other products they called it dual flow (2 rebound circuits). Regarding the low-speed adjustment, it depends on your style of riding and the trails you ride. If you like the front a bit more firmer, or if you do flowly trails or park, then add some low-speed comp (LSC). If you like the fork more soft and spongy or if you ride a lot bumpy and rocky trails use less LSC. The more LSC the more firmer and stable the fork would be, with less diving, but if you put too much you start to get some harshness. Bye

[@andreasbmx100]

really nice video , what's your opinion about custom tuned suspension ,I am talking for mtb .

[@andrextr]

I don't have a strong opinion on that but I think it depends on the objective of the tuning. But I would say that most of the time people don't need a custom tune, they just need to adjust the shock properly... There are some cases were the shock adjustments range are not enough for a specific rider, in that case it might be needed a re-valving on the internal tune. Or for instance, there are some basic shock which lack some adjustments, like high-speed compression and so on, so you need to re-valve in that case if you are aiming for a specific objective. Shocks like CCDB or Fox X2 already have a quite good adjust ability range with 4-way adjustments, they can fit most types of bikes and riding styles out of the box, so in this case a re-valving is not needed on most cases. Bye

[@Eric-ue5mm]

Amazing videos. Could you review the Canyon Spectral? Thank you my friend!

[@andrextr]

I already did the model but I didn't the video yet. But the Spectral is not very different from the Strive. Spectral has a progressivity of 35% which is more than the average for a 140mm bike. Anti-squats are around 75% for a 32T. So it looks like they optimized the frame for a smaller chainring like a 26T. Anti-rise is low (45%) as expected for a horst-link design with a rocker link with an horizontal type of configuration. Overall is a good bike, however anti-squats could be a bit higher on a 30-32T (but since they also sell this frame with a 2x10 option, they did the compromise to work well on smaller chainrings). Bye

[@Eric-ue5mm]

Awesome! Thanks a lot for that.

[@maxschubert3940]

+andrextr Hi Andre, I really like your videos, they are well explained and interesting. I have a question/suggestion regarding the topic of rebound however. In your video you assume that both the weight of the bike and of the rider are sprung mass, which makes the use of critical damping very important. In reality however the rider is not static and can absorb impacts/vibrations etc. aswell. In this way a lot of other people recommend much faster rebound speeds because the rider already adds to the rebound by using his arms and legs. (for instance Vorsprung suspension: kzbin.info/www/bejne/pIe9n6yoo9atmbMm10s). What do you think about this? Could you simulate the damping applied by the rider to the system by adding a secondary spring/damper setup above the sprung mass (which has to be lowered to the bikes weight) to your simulation at 13:05 in your video? I would really like to see the effects of this. Realistically the damping of the rider would be quite slow as a rider cannot follow high speed oscilations with his arms and legs that well.

[@Aveal]

this is incredible well explained! thank you for that! Have you considered a Patreon account?

[@andrextr]

+GimletSc Thank you. I already considered it but never did it. I only have the PayPal donation link :) Bye

[@madoxx1911]

Mechanical engineer here with a question: I like your explanation of rebound speed and it's effect on suspension performance, but I wonder how applicable the conclusions are to a real fork/shock because I'm not sure if your simulation models include compression damping as well. Disregard this comment if they do, but when you programmed your suspension simulation did you include a separate force vector in the direction of shock extension (F_y = -cv where k is the coefficient of compression damping) as well? Most modern forks and shocks allow you adjust both compression and extension (rebound) damping to independent values and I'm curious to see an animation of how these two inter-related parameters affect overall suspension performance. If you redo the simulation with compression and rebound damping having independent values the sum of forces on the suspended mass would be: m*a = -c*v - k*x where c is c_comp when x dx is negative and c_rebound when x dx is positive.

[@andrextr]

Hi Alex. Thank you for your question. I'm not an engineer, I'm a biochemist eheh. Anyway, this simulator is a free and cheap one and it doesn't allow much tweaking, it only allows changing damping ratio. Yes it does have compression. In real world the damping of a shock is 70% for rebound and 30% for compression. So, the rebound has a more important role in the overall damping. The animations were mostly a visual aid to explain the transmissibility concept. The more damping (either compression or rebound) the more stable the ride would be over low-speed frequency bumps but the harsher will be over high-speed bumps. It would be nice to have a better simulator to simulate different reb&comp damping for the different shaft velocity (to simulate high and low speeds comp & reb. damping), but this is the best I can do :) Bye

[@diego81990]

Hi, I bought a kona hei hei dl race from 2016. Im finding Im quite slower than my normal hardtail. Kind of feels like Im losing a lot of force through the back shock. I mostly drive XC style routes. Do you have any tips? Im currently weighing 75kg. Have the sag’s set at 20% in front and 25% in the rear.

[@Pogost1ck]

What software did you use for the animation/simulation? Does it output usable data?

[@andrextr]

It's the Algodoo. It's not a great tool, but it's free and it works OK on simple stuff. Yes you can output graphs to excel. It's good for physic classes :)

[@pintospirits]

I think high speed rebound is recovery from big impacts, so high shaft speeds rather than high frequency. High frequency bumps would result in lower shaft speeds so that is lsc and lsr

[@playlunia1]

Excellent video! I'm a mechanical engineer. Can you share what software do you use to create these simulations?

[@andrextr]

It was algoodoo… its a free tool… you also have working model

[@pavementhum]

Nice video. I'm comfortable adjusting my low speed rebound, but how you determine the best setting for high speed rebound?

[@andrextr]

Check this video (ep.7: kzbin.info/www/bejne/j5vUnWShet2peac ) after minute 9:00. I hope that this works well for you. At the end of the day, independently of the setup, check the setting with the curb test just to confirm that you are not getting to much bounciness. Bye

[@cscsw]

high speed rebound damping means shock extends after a big hit. The shock is compressed deeply and then rebound. It isn't directly related to "bump frequency"

[@michaelracine3745]

Andre, you usually have answers before I think of the question but here's one I'm wondering about. On rocker equipped bikes while the bike is unweighted the seat stay contacts the rear of the rocker at close to 0 degrees. As weight is added the stay pushes the rocker to an increasingly obtuse angle which seems to decrease the mechanical advantage of the stay and wheel, which isn't what's needed. Is this to counter the rapid ramp up of the air shock? But how do bikes with a horizontal shock deal with the progressiveness? Bikes use coil and air shocks with the same set up also so what's up , O Great One.

[@andrextr]

The progressivity can't be seen just by the position of the rocker. For instance the shock position also affects the leverage ratio (see Ep.4 kzbin.info/www/bejne/bWmndWtom91ng5o ). For instance, the Canyon Strive and Radon Swoop have an horizontal rocker, however, Strive is much more progressive than Radon. This also applies to vertical rockers, for instance, NOX EDF or DHR are very progressive while Scott Genius LT is slightly regressive. Not sure if this answers your question :)

[@janezpracek8256]

Did you placed riders mass on the saddle? When riding rides mass is usually applied mostly through the pedals... Otherwise great video...

[@andrextr]

I like to ride seated with open legs :D

[@dariusdamonte4685]

Great video! If I want my fox dhx2 to give more pop for jumping what should I do? Decrease low speed rebound? Thanks!

[@andrextr]

You can decrease (make it faster) High-Speed Rebound (HSR) which will enable the bike to recover quickly from deep travel. This will amplify the "pop" effect when you preload the suspension with your body weight on jumps take offs. Be careful because faster HSR make the bike more instable after a big hit landing (the rear wheel does not get "planted" so wheel and it can lift from the ground after impact).

[@dariusdamonte4685]

@@andrextr thank you! I I sped up HSR rebound 2 clicks as well as the LSR. It has noticeably more pop. Thanks for the heads up on getting bucked on harsh landings, I'm known for casing jumps.

[@cuaumario]

what software do y use for the animations or how can i create one??

[@andrextr]

In this case I used Algoodoo, its a free software... not very professional but its nice to play with

[@DaStuntChannel]

The best suspension would have a slow rebound on the amplified section and fast rebound on the absorption section

[@juscelinocastro]

Olá André. Você poderia analisar a nova polygon square. O que ela tem de tão especial? Seria maior sensibilidade e maior plataforma (antisquat)?

[@andrextr]

Olá! Não tem nada de especial. Apenas puro Marketing. Há sistemas melhores e mais simples. Fiz um breve video mas está em privado porque o video está muito simples. Mas aqui vai: kzbin.info/www/bejne/hmrcnGuCjbOrf7c

[@StandardSublime]

So with a shock that has a HS&LS rebound adjustment, it would make since to adjust the LS to the critical damping point and the HS to be relatively open?

[@andrextr]

+StandardSublime Yes thats almost it. But by default the HSR is already much faster than the LSR for the same number of clicks (you can't compare them by the number of clicks). So, to avoid extreme setups my advice for a starting point is to tune the shock as suggested in episode 7 at minute 9:00 ( kzbin.info/www/bejne/j5vUnWShet2peac ). Bye

[@broyerthibault9074]

I'm not sure that high frequencies bumps are relative to highspeed rebound, because you never go faster through a rock garden (deep in the stroke) than through braking bumps ...