Motorcycle Suspension: Choosing Spring Rate, Setting Preload and Adjusting Preload Explained

Learn how to choose your spring rate, set your spring preload, and adjust the preload of you motorcycle's suspension. Understand and appreciate how to get more out of your motorcycling experience. Learn how to set your motorcycle up for you. Learn what spring rate to use for your weight, for your speed, and for your riding conditions. Learn why setting your ride height with preload, like on a KTM 1290 Superduke EVO, is not the best way to adjust your chassis attitude.
Please do not be intimidated by your motorcycle's suspension. It is easier than you might think, to make your motorcycle better, safer, more enjoyable, and of course faster. I hope you enjoy this two part series on understanding your suspension.
Hooke's Law is the equation that can be used to figure out one of the three elements needed to choose your appropriate spring: F= KX. You can read about it here: www.britannica.com/science/Ho...
Special thanks to Gavin Botha, David Stanton, and John Chen for their knowledgable contributions to this video.
GoGo
Timestamps
0:00 - Intro
0:38 - Choosing the Right Spring for You
4:52 - Spring Preload Explained
12:10 - Why We Need Sag and How Much
17:34 - Different Sag For Different Riders
21:29 - Debunking the Myth of Adjusting Preload To Soften Spring Rate
31:18 - Why Less Preload Made Me Crash at Bridgehampton
33:06 - Why Preload is Not The Best Way to Set Ride Height

[@ksmotoshed7961]

Excellent!! One of the few videos that say things as they are, great explanation! I thought 39 minutes was going to be to much but it felt much shorter. Thank you!

[@WilliamSudek]

Sag, compression, rebound, but the most important and useful thing I learned today. And the thing I will use most in everyday life is how to sign bullshit.))) You changed my life and I can't thank you enough. I'll set my bike up tomorrow.)))

[@snappers_antique_firearms]

Wow. Great video i learned so much and you made this far easier to understand

[@bryanhaynes8761]

You haven’t finished yet Eric, you need to do a 3rd video explaining how much sag should be set at, measuring and setting it correctly to complete the series! 😁

[@nickmcalpin10]

25mm! 🤣😂 For real though, good rule of thumb 20-30mm rider sag for track 30-40mm rider sag for street. 5-10mm ish race sag.

[@grahamgraham4263]

And if the reason why there are different sag goals for the track and road, it would complete the circle of understanding. You’re doing a fantastic job with this video series focussing on suspension.

[@DangarMarine]

Thank you for this video. If the formula was all there was to it we would all be identical people riding on identical roads.

[@superduked33]

100%

[@Andrei_K1G1K]

100% agree about static sag! Fantastic explanation! Static sag is the biggest load of BS... I'm about 280 and static sag is mostly for the birds... And the shock length/preload totally makes sense. In fact when I ride my R1200RT when I add the right amount of preload, my ass hurts less while riding for long distances BECAUSE the shock is longer therefore putting me more forward and on to my sit bones vs the meat of the subject... And people get all these expensive seats when getting the right spring is the best solution. Now on my G1K I'm just getting to dialing the suspension. There's also a thing to talk about the rotational point of the bike with Telelever and regular forks because they do not rotate around the same axis and how that affects suspension but that's a completely different topic altogether.

[@superduked33]

100%

[@SudeepC1973]

You are a good teacher. I also have had a hard time in school. You have a nice way of explaining things with examples.

[@superduked33]

Thank you so much Sudeep

[@colinrhodes1838]

Great video - Thanks for the teaching lesson - I just got your 10mm ride height increase solution for the road and at last my SDR is absolutely dialled in - I’m thrilled - You are one awesome dude - dude.

[@superduked33]

I love hearing this brother. Thank you for the feedback. Ride safe and hard

[@rossanodimonte2520]

Eric i believe for a overall better understanding there is a further point to be cleared. When we talk about a stiffer spring compressing less than a soft one we need to make a distinction of effects. Let's talk about the fork that is more intuitive to visualize. If we talk about the braking phase, we apply a compression force from the top of the fork to the ground due to inertial forces. Being the ground quite firm 😂, the spring has no chance than compressing. A stiffer spring will equalize the same force with less travel. That's easy to visualize. If we instead talk about the bump absorbing, the situation is a little different. The force is now applied from the ground up and is the multiplication of the unsprung mass (weight of the wheel+tyre+disc etc.) by the vertical acceleration of the wheel...which depends of the vertical height of the bump and the time it takes for the wheel to go over it...which depends on the bike speed.😅. So in this instance the travel of the wheel is fix and not negotiable, it MUST go over the bump. If the bump is 2inches high, the travel of the wheel is going to be 2 inches. Will the spring compress the same amount? Well it depends on the spring rate. If the spring is hard enough(rate, not preload) that 2inches of travel generates enough force to exceed the bike+rider weight onto the front axes, the spring will actually lift the bike instead of compressing itself. So it is true that it will compress less than a soft spring, but only because it is transferring energy to the sprung masses. Hence the harsh ride feeling and the damping issues due to the little oil volume moved inside the valving. Hope this gives people more understanding to make the right choices

[@stevenrapa4014]

Excellent comment. This is exactly what was happening to me last season. I race an RVF400, but the stock forks are crap for adjustment. And my friend suggested 675 forks. He runs them with 8.5n springs... And its perfect for him. But he is probably 20kg heavier than me. I put in 8.5n springs and could just about get 30mm of rider sag with zero external preload. I didnt understand any of this at the time and was relying on other 'experts'. So one suspension guy, cut my internal preload spacers by 20mm... Which meant my Rider sag could be 'correct'... However I was constantly sliding the front all season, every turn, and going slower than on my stock front end... After deciding to teach myself, I realised what was happening was exactly as you describe. The spring was basically moving me and the bike away from the ground over ripples and bumps, rather than suspending me and tracking the ground. Now I have 0.75kg / mm springs and its like a different machine.

[@Bullet62013]

Great job GoGo should help lots of riders understand the DARK MAGIC..lol. The Break down on Pre load adjustment was spot on, I remember the first time my suspension guy explained this to me 12yrs ago, being more like ride height adjustment and how it would effect my trail numbers which used be like speaking Chinese to me. I Also learned you can have the best suspension under you setup by your suspension guy, which is usually just a good base set up and not dialed in for just you, learned you have to find the settings that work for you ride and what you feel the bike is doing. We all ride around the same track on the race line yet all riders have different set ups, similar but different. I remember when I first started racing at Louden and Shane Narbones Dad was pitted in the garage behind me, I was explaining to one of my racing buddies a problem with my bike not finishing a turn and going to wide on exit, just couldn't get in the gas early like everyone else and hold a line.....well Shane's Dad was pretty good with suspension s and was listening in, hey do this this and that....4 clicks of the suspension and I dropped one second off my lap time from 4 dam clicks, like a different bike, learned it wasn't my ability to ride my bike that was the problem it was the inability to understand what the problem was and how to adjust my suspension properly, one of those UREEKA moments and at that point I decided to learn everything I could about suspension adjustments as your current set up can only take you bso far, as you get faster those settings become obsolete and are actually holding you back not your abilities. Point being is what your suspension is doing and how to adjust it makes riding your motorcycle more enjoyable on the track or on the street, wether you have 40hp or 190hp the one constant is your bike is hitting bumps and improving this area is beneficial for all riders, this is where GOGO'S vids putting things into layman's terms can help everyone.... hope you all appreciate it. Excellent Job GOGO....A++

[@superduked33]

Thank you so much brother. Love your stories and the players involved. Feels like home. And I agree, every one and every thing and every lap time is different. Takes different things, causes different things. That’s why there is no single answer. And no single formula to solve all problems. Best thing you can do as a rider is learn to listen to your bike. Learn to adjust your body and your technique to either react to your bike differently, or cause your bike to react to you differently. Every single thing is connected to every single thing out there. And in life.

[@nealmanis1378]

😅 I absolutely love your teaching. Your cracking me up at the same time.

[@superduked33]

😁

[@Flipper-fe9qu]

Great information. Definitely more light in the room now. Thanks so much for taking the time Eric 👍

[@CAPTAINAUSTRIA307]

I know how much work goes into such a video - thank you! Both parts are very enlightening!

[@grahamgraham4263]

Excellent and clear explanation.

[@adriancorse13]

Perfect video. Thanks a lot. 👍

[@waggywagstaff]

Love this!! Best video I have seen, and I am a club racer I’m the uk, never thought about it like that…. 😂❤

[@robertswafford4145]

These videos are incredible!

[@DjScarhead]

you explain it perfectly , big thanks for that 🤗 it helped a lot 💪

[@jimjim753]

Thanks for all the work u put into the yr videos...... Snow is finally melted here in minnesota... ..ready for road America in a couple weeks..

[@superduked33]

Good luck brother

[@bkkfilmdog]

Excellent many thanks. Watched it all..

[@dancorbett8139]

Really helpful! Thank you

[@chicagodrive6261]

Thanks for the video Such a relief seeing this video after seeing some misleading popular videos out there Your Famous

[@AMPJ08]

This is ready for a suspension debate with Dave Moss LOL

[@superduked33]

🤣

[@robsonenduro3316]

good stuff!

[@Putteblaze]

Friggen epic explanation👌

[@superduked33]

Thank you man that means a lot to me.

[@apantelop]

Loved how you explained this, made me question some of my own understanding but in the end I gained a better and also intuitive understanding of what preload does! It could be great to also cover this in the future: if a given rider can achieve desirable rider sag numbers with two different spring rates, how does one choose the right spring for a given scenario? Your race at Bridgehampton could be such a scenario, another one could be a rider becoming faster over time, or even the type of bike or track or road as those could determine what type of bumps one would hit and at what speeds. Cheers!

[@superduked33]

Excellent ideas my friend. I will do this. Thank you

[@marijnkramer6897]

This is making it a lot more clear. Now I am going to experiment with the suspention on my SMT. But the front, same way? But the adjust it with the fork hight above the tripleclamp?

[@jonchristianpetersen]

Salling towards the ligt. Thank you!

[@jrams.g]

Great stuff, thanks!! Is there a 3rd video for compression and rebound?

[@superduked33]

My goal here is to explain the science we all face, not so much the preference. Some like it hard, some like it soft, some like a bike that barely moves, others like me like a bike that talks to me. Loose is fast, to me. But it's so much a preference thing that me suggesting my way is THE way feels a little off to me. I guess I could explain the physics of it, which would definitely help people understand better what it happening and why. Maybe I'll do that.

[@jessefpv9217]

I love How he’s Speaking to me like in in 3rd Grade. Lol I love it. I can finely understand lol

[@shawnmiller6335]

Thanks for confirming what I was thinking.. Just rebuilt my forks and shock with softer springs and better valves and shims my weight and their numbers for preload and sag are horse shit no way I can get the sag they recomend adjuster dont go that far

[@MrBCRC]

Thank you. And yes I understand. ;-)

[@superduked33]

You are welcome!

[@ehtikhet]

It’s not black magic, it’s not arcane guru nonsense. It’s science 👌

[@jaredallen8054]

hey eric thanks so much for the awesome information. i just got to know... Did you ever find a cylinder jug for your 1290?

[@superduked33]

A KZbin subscriber shipped me a used one from Australia, KTM sent me a used one from the warehouse, and just in case either or both of those options didn’t pan out I bought a used 2022 motor off eBay. In the end, KTMs cylinder was from an RC8, so that didn’t work. The Australia cylinder got stuck in customs for forever so that didn’t work out. But the used motor made it on time, and we jammed it in and made round 2. Only problem was zero sleep for days, not enough nutrition because I was too focused to stop to eat. So by the time qualifying came on Saturday I felt like my body was disconnected from my mind. Racing was completely f’d. Dangerous even. Left with a win, a second place, I pulled out of second in the third race, and never even started the 4th. So basically round 3 will be my round 1 this year. :-)

[@chrisvondetten7650]

Here's a scenario, I'm on a Triumph STR675R, but the rear shock is far to harsh no matter what I do. I was looking at swapping it out with the rear shock from a 2013 R1. The Triumph spring rate is about 12kg/mm, where the R1 is 10kg/mm. The R1 shock comes with high and low damping with hydraulic preload. I weigh 83kgs maybe 85 with gear. Thoughts?

[@damytzeus]

hey gogo, thank you for video. great info. what's the relationship between spring rate and rebound damping? e.g., would installing heavier spring necessitate more rebound damping?

[@superduked33]

Yes. Valving controls the spring. That’s it’s #1 job. So a heavier spring needs heavier valving. Not every spring change needs a new valve stack though. Sometimes just adjustment of your clickers can be enough. Depends where you are in your valving window

[@damytzeus]

@@superduked33 awesome. thank you

[@rossanodimonte2520]

The answer is yes, but It is related to the oil volume moved and not the spring rate itself. As Eric explained in the video, two different springs will both compress to the point they reach the equilibrium with the external forces (i.e. weight). The difference is in the travel they compress to reach that equilibrium point. Softer rate will compress more. At that point they will both release back exactly the same amount of stored energy, but the stiffer rate spring will only give the shock a limited travel (read oil volume) to damp that energy. The lower the oil volume going through the valving on the same amount of time (read flow rate) the harder to control the damping

[@rossanodimonte2520]

In the case where a stiffer spring with little preload would equal the travel of a softer spring with a lot of preload (i.e. setting the same sag), with no further travel, the damping is the same for both springs. With the compression damping instead, softer springs require harder valving and/or moil oil volume (fork) or gas pressure (shock) to help absorbing energy and reducing the travel

[@damytzeus]

@@rossanodimonte2520 awesome info. thank you much!

[@AntaresSQ01]

Great video but i think the whole sag + preload + spring rate explanation was a little roundabout. In my mind in simple terms: Spring rate decides how much of your stroke you'll use hitting a bump, assuming you're already in your travel range. Preload adjusts where you rest in your travel range (your sag). What you were explaining at 31:14 i think of as just taking the slack out of the spring. Please correct me if I'm wrong.

[@superduked33]

I have no authority to correct anyone Antares. This is how I understand it in my mind. Maybe my mind is roundabout. Grab your camera and give it a go. Sounds like your slack idea speaks to you clearer. Maybe it will to others as well. Knowledge is power - share it brother

[@AntaresSQ01]

@@superduked33 Don't get me wrong I'm watching this video for a reason, I do have some vehicle dynamics experience though so maybe I only think what I think because I (would like to believe) i understand suspension fairly well, for someone that you're intending this video for they might very well need all the loops, keep it up! Looking forward to the damping video 😁👍

[@tumbleweedlyfe]

Im at 87kg ,how would the stock gen3 set up suit for quickish canyon road riding ? Thanks

[@superduked33]

The 1290 Superduke Gen3 is an epic bike. it's fun, it's comfortable, it's cool as hell to ride. But it needs a nudge of help before it can earn the quickish canyon riding badge. In stock trim the Gen3 comes with a LOT of trail, a flat swingarm angle, and a pretty progressive spring rate. All three of these characteristics can be improved, from mildly to greatly, by using one of the +10, +15, or +20 Sport Links that you can buy at Superduked.com. Totally transforms the bike from a slow steering, difficult to exit turns hard while maintaining your line, unstable-at-times motorcycle - into the bike that it is advertised to be. Turns like a cat, powers out of turns on the rear wheel driving the tire into the ground, keeps its nose planted under acceleration, has excellent corner speed, and the more linear rate of the spring gives you a more consistent feel throughout the shock's travel. Best upgrade / least $

[@tumbleweedlyfe]

@@superduked33 thanks, yea I watched your video regarding the link upgrade. Sounds like a must have since the shock is not length adjustable. Kev

[@noext7001]

how do you know the travel distance of the shock and the bike ?

[@superduked33]

If you remove the spring from the shock and reinstall it, you can measure the travel very accurately with the bike lifted off the ground from the frame, so the swingarm can extend fully without touching ground.

[@pafsrh4744]

i lost you about the static sag and rider sag 35mm, 50mm any mm etc.. i need physical examples, and physical measurements point to point for the reasons

[@pafsrh4744]

still like the info though

[@martinlee7706]

which is the better shock or better than the wp7749

[@superduked33]

Kwok, in my experiences with the WP, both shocks I used were valved like water. And one of the two blew a seal the first weekend. My first weekend on the Ohlins was very compromised. Not enough time or development work. But I already feel better about it than the WP. Right off the bat I had the valving changed though, so my comparison is a little skewed. My buddy Gavin has a revalved WP and it seems to be working nicely for him. Interestingly though his data looks fantastically different than my data. I am using a lot more stroke than he is. More to come on this - we are doing a test day. Eddie best race which I hope to film and share here

[@1980jamesm]

So what you're saying is that preload is just a crude way of adjusting ride hight/geometry once you have a spring that suits the force. And you shouldnt really adjust preload at all once you have a bike in a working range, wet or dry? If so, then technically in the wet the forced should be less when braking/accelerating, and adjusting the preload window is actually kind of right as you are putting the bike into its working force window, but wrong in the way that the you are shortening the working window and really you should change the spring rate to relate to the force change. When you decreased the proload in the front and crashed you moved the bike down its working window and applied enough force to push it out of range. If you hadnt decreased preload you would have had the right window to play with. Force is the problem, a 50kg rider who brakes super hard might want a higher rated spring than a 100kg rider who carries corner speed. Black art, as you say.

[@superduked33]

I agree with you James, the right thing to do would have been use a softer spring. Adjusting my preload, backing it off, only put me closer to bottoming out, and farther from beating Richie. Which, alas, I never did.

[@1980jamesm]

@@superduked33 MJ's loss.

[@Bullet62013]

I keep asking GOGO for some sag numbers but he won't divulge this critical info..... He's holding back! Haha

[@superduked33]

🤣

[@sol2406]

do you also share on instagram?

[@superduked33]

I probably should but my social media bandwidth is stretched as it is..

[@sol2406]

@@superduked33 I understand, but I'm sure all KTM fans will be attracted to follow your posts

[@erixlast6020]

Again, one like is not enough!

[@superduked33]

Thank you erix. Makes it worth the work

[@jonchristianpetersen]

Meant walking😂

[@alexwhatley1190]

Can you send me a link for buying suspension parts for my Gen 1 (2015)? I came in 2nd again this weekend and I'm getting really frustrated with my suspension. I feel like I should pay you a retainer fee for all the questions you've been helping me with. Thanks again for all the tips and vids.

[@ericgulbransen2393]

Thanks Alex. Means a lot and inspires the next video. ..Your Gen1 has no link so I can't make one, but there are still things you can do to help that bike get around a racetrack. Two major things are gearing - which can put your eccentric in a better spot for wheelbase and for ride height - and a height adjustable shock. With those two great moves in better directions your Gen1 will fly.

[@alexwhatley1190]

@@ericgulbransen2393 I have my gearing spot on now with 2 up in the back and 1 down in the front and I added one link to the chain that was provided to put the rear wheel as far back and down as possible. Is there a brand of shock for the rear that works best? Front forks? I'm going too fast for the bike now. I know it has more to offer. I started dead last in both races this weekend and was in 3rd by turn 1 in both. The bike is amazing at that but the high speed braking while entering a corner and maintaining high corner speed is all muscle on this thing. I need stability bad.