An easy way to look at it: A coil spring shock has spring travel and suspension travel. With zero preload, they are one to one. Preload uses up spring travel but not suspension travel. A 10 inch spring with a spring rate of 100 pounds per inch and 10 inch travel shock without preload will both move 1 inch under 100 pounds. An inch of preload decreases the spring to 9 inches but the shock travel is still at 10 inches. To move the suspension an inch, it will take 200 pounds, the spring has already moved an inch with the preload and the next 100 pounds moves it the additional inch. The spring rate does not change. The greater the preload, the greater the weight needed to compress the shock. The spring will compress at it's constant spring rate. It gets confusing unless you separate the actual spring travel separate from the shock travel. With two inches of spring preload you will only get 8 inches of shock compression and 2 inches of shock extension.
I think that this is where people really get lost in this concept. You need to separate the travel of the spring and damper like you have stated. This is a good explanation though.
wow very interesting. all the articles and reviews i've read always say setting sag is the first thing you should do and is considered the most important step to setup first. they even say rebound and compression dampening is a crapshoot until you've setup sag correctly.
The point here is that you should set up your SPRING RATE properly. Sag is only used to get spring rate in the right ballpark, but it's not precise and there is no fixed amount of sag that you should have because every bike has a different characteristic and every rider has different requirements. For forks, even measuring sag is pretty useless because you can measure it five times without making changes and get results that vary between 8% and 25% (which should indicate a 300% difference in spring rate) simply because friction and body position mess with it so much.
If the spring is slightly too long and needs to be compressed a bit to fit, is this an issue other than effectively adding a bit of preload. Why isnt the spring length shown to prevent ordering the wrong one..even with a tolerance %.
Hi nice video, I have dvo jade 250x70 and i would like to ask what is the correct spring length for my shock i have 450x2.75 or 450x3.0??? Thanks in advance
I'm a bit of a noob when it comes to coil springs but did my research on spring rate before buying springs. The manufacturer recommended 500lb, online spring calculators recommended 500lb, but linkage software recommended 550lb. I bought a 550 and a 600. Even with the 600lb spring my sag is at 38% with about 1 turn of preload. I'm thinking I should be running a 650lb spring then right? Bike = Propain Tyee 2020 CF 29
Wait, if I've learned anything from Steve, is that I shouldn't rely on sag numbers! Shit lol. K I guess I will have to huck it to flat and see how it feels lmao
Why don't mtb shocks have a second collar to lock the first collar in place like a motorbike has? Would it not work great to keep preload at a minimum without the possibility of the spring coming loose?
Some shocks have locking mechanisms like grub screws through the side of the preload collar to achieve that. There often is not space for a second collar on there.
Does the preload affect my lowspeed rebound ? I felt like I was between 2 clicks of lsr and increased just 2 clicks of preload now the slower setting feels just on Point.
I have a ohlins coil shock on my stumpjumper and no matter what spring I get it seems to sit around 40-45% sag. from a 458lb spring clear up to a 640lb spring and no difference. Im not new to mountain bikes but new to coil suspension. What am I missing? Thanks.
Cheers, mate. These tuesday tune videos are great. I just bought an ex-demo Orbea Rallon with a DHX2. I was interested to hear your thoughts on sag. My current coil is an SLS 450 2.75, and I reckon that's about right for my 76kg riding weight, but am I right in thinking that the (approx) 30% sag I need is based on the 2.75 figure (this would be about 20mm sag)? In Fox's diagrams it just suggests that the shock travel is equivalent to the exposed stanchion, but that's about 10mm less than the 2.75 inches on the coil. Any guidance appreciated here in Wollongong...
How would you start to set up your coil shock if sag isnt important. Minimum preload. Rebound and compression etc mid adjustment and session a piece of trail? Adjust one at a time to get the right feel as its still a comprise on changing terrains. Even messing with tyre pressures is a pain..
I don't think Steve is saying sag isn't important, just that the actual figure isn't important other than a way of measuring for comparison. Vorsprung did a good video here on the different effects of spring rate vs compression damping so check that out if you haven't already. When I'm setting up suspension (and I'm an amateur) I ride a section of trail that is fairly typical of what I ride generally over and over, starting with each setting in the middle then doing runs with 2/3 clicks either side. Whichever way (more or less compression) feels better I then keep repeating the process until it feels worse.
@@KieronHoward Hi Kieron, Ive just put a Cane Creek IL shock and Valt spring on my bike. I tried a 500lb spring but it was too stiff for me, 90kg, so now have a 450lb. It came with all settings at mid point. To get more pop for bunny hops etc I have upped the fast rebound 1 turn which is better. I will continue to experiment but it is much better over rock gardens and flat drops. What bike and shock do you have?
@@KieronHoward I couldnt find my bike, Cube Stereo 160TM 2016. I did use their spring calculator and it suggested 500lb but I have changed it to 450lb after a big crash. I was bouncing all over the place on a fast DH and one foot came off the pedal and I hit a tree. The pain of pregress lol
The 2016 Cube Stereo 160 C:62 and C:68 are both on the Dialed app. I don't know the difference between them and the TM, but it's highly unlikely that the frame is different, which is what matters when calculating the shock settings. I'd use on of those as your starting point.
Yep, 2 turns on a rear shock is not crazy. Sometimes we see people with 12 turns - on a 500lbs/in spring this is equivalent to about 250lbs of preload!
The frame will, naturally by design, slow the shock down the further it gets into its stroke. This is progressive. If its a linear frame, the shock will need the same force throughout the entire travel, and on some frames near end of stroke, blows through the last 20mm of wheel travel really quick. This is where a progressive coil spring can help on a typically linear suspension designed frame.
Jamie Dwan my question was more why should you aim for 30% sag at the shock when on a progressive frame this equals far higher sag at the wheel. People generally recommend higher sag for progressive frames which to me, sounds counterintuitive. Seems like progressive frames should do better with less sag at the shock.
@@andreaslundindotcom It is where shocks are set to be in their more active, supple range. 30% is a general guide/starting point, and rider needs to adjust settings from how the bike feels on a particular trail. If the bike is more progressive, the range of suppleness is larger letting you have a higher sag point if you like that feeling, and will take a harder impact to get you to your full travel. I get what your trying to point out. Have a look on RU-vid for andrextr his episode 3 of rear suspension is damn good.
Jamie Dwan I have seen those videos but it doesn’t really explain. I don’t care about using full travel only smoothest ride. A progressive bike is more supple in the early stroke so shouldn’t that be used by having less sag? More sag means you will hit the wall of progression which can be harsh. We have sag for negative travel. More progressive frame means more negative travel so all things equal less sag should be ideal for progressive frames??? My bike a YT Capra is progressive and I currently run just a touch over 30% but wondering if 25% wouldn’t be better. Need to try a heavier spring. Goal would be better dynamic ride height and more cloud feeling.
@@andreaslundindotcom lower sag would harden your ride up so you would get nowhere near your full travel. You have 160-170mm of travel so why wouldn't you want to use it? What year and model capra do you have. I am looking at that for my next bike.
This is pretty confusing... first - the bulk of my suspension experience is with coil over shocks on off road vehicles... but it's the same principle - a shock is a shock, and a coil spring is a coil spring. Assuming that the spring rate is linear - compressing it using pre-load does not effect the spring rate - it remains linear. But it does impact ride height (expressed as sag in mountain bike lingo). So it does not impact the amount of force required to either compress or extend the spring from static ride height - makes zero difference. Sure, you don't want to add so much pre-load that the spring reaches it's block height before the shock reaches full compression... then the spring rate will ramp almost infinitely (that is, the coil windings are all against each other - so it essentially turns from a spring to a block of metal).
Preload absolutely affects the amount of force needed to move damper from static condition compared to coil with no pre-tensioning. Hence why the graph he has drawn shows the spring curve shifted up for the preloaded spring. As a spring is compressed the force needed to continue compressing it increases in a linear fashion. In a preloaded spring on a damper at static condition the force of the tensioned spring must be overcome before the shock even moves. Additionally the force then linearly increases from that point.
I feel like such an idiot watching these bike videos! I am an educated person but I am a noob to the MTB world & I am trying to learn about my bike & all the little things on it. When I watch these bike videos I feel like they are geared towards bike technicians & just get lost in all the jargon. Is there like a MTB for dummies or something?
