I just installed a new Ohlins TTX DU931 and linear link on my 848 Evo. The shock has a 150mm 90 spring. I was able to get the recommended rider sag of 30mm by lowering the hydraulic preload adjuster to its max position, about 8mm of preload. (I understand the entire preload adjuster mechanism can be further moved down to provide even more preload). My free sag without rider is 11mm. This got me wondering if it's better to use a stiffer spring with less preload? In my case I could move up to a 95 spring. What would be the benefit and drawback? In what situation if any would it make sense to use a stiffer spring with less preload or a lighter spring with more preload?
You really need the lightest spring rate that uses pretty much the full suspension movement range without bottoming out, which is trial and error, or put your trust in a suspension expert who has already done the experiments.
I am no suspension expert, I had my old oem sus sorted by 100% and they did it in a very basic way using feel. It worked well. I had my suspension set up years ago by a top road racer and they measured everything including static sag. Not just rider sag. If the preload is incorrect, I beleive it can effect static sag? in that the bike may not return to correct measurement. This might not be correct? but, there is a video online about... preload, impact on sag. Sorry if is misinformation. I am trying to think if the spring rate is stiffer with less pre load will it behave the same as lower rate (lbs) and more preload. I leave to the experts. I guess damping takes care of the rebound and compression? sounds very critical if it is where you need it to be now. Interested in the answer.
As above really. As soft as you can get away with that doesn’t bottom out under aggressive riding. Rider sag not static, as a spring for the bike may be right but is vastly different with a 12st or 20st person on the bike.
Totally depends on taste. I tend to prefer a softer spring on the front with a fair bit of preload and a hard spring in the rear with a few clicks. I'd usually say with the front, go for the softest you can get away with as a rule of thumb Obviously generalising a little here, but you get the point. There will be arguments for the pro's of either but ultimately it comes down to your taste and even the application (bike) it's fitted to. Conditions, pace, tyres, rider/riding style/braking characteristics blah blah blah. Too soft is easily managed and still gives you feel, too hard lacks feel.
For the 848 Evo I stayed with a 85nm spring I think, maybe a 90, but MCT fitted a shorter one for me that meant I could get more sag dialled into it which I did at a local suspension place, I was also advised to lower the rear ride height as it pushes the front a lot, then when the local place set it up they actually put 3 turns of preload into the forks to get them riding higher in the stroke. Those changes alone did make the bike less physical to ride, less weight on the wrists and tbh steered as well if not better
To be fair the stock 848 ergos are like doing a permanent stoppie. I've never ridden anything else quite so wristy.
Thanks guys. Makes sense. I should have mentioned that my bike is mainly used for canyon riding with the occasional track day. I am also pretty smooth on the throttle while exiting corners so hopefully this 90 spring will be perfect for me. I was just thinking that with perhaps a 95 spring with less preload, there will be less force needed to overcome the preload so at least during the initial shock travel the ride would be more compliant. But of course once the preload is overcome the 95 spring would result in a stiffer ride. I did talk to a few suspension experts and they all said I was right in between a 90 or 95 spring for my weight and riding style. I really dont want to remove my shock again!
If interested, these guys have a calculator to give an idea of ideal spring weight https://racetech.com/ProductSearch/
