I’m getting back into the game after a several year hiatus. This time around I’m wanting to take the time and money to set my bike up right. I’m on a 2026 yz250f and weigh 220lbs. I don’t plan to race again but if I had to categorize myself I’m probably a low to mid pack local C class rider on a good day. Among all of the spring rate calculators the racetech one has me a bit stumped because it seems to have me going up quite a bit on the rear spring but the fork spring appears to be the same as stock. If I only bump up in rear spring rate won’t that likely make the bike feel imbalanced? The numbers that I found for the stock fork spring rate is 4.7 n/m and the racetech calculator is matching me with a .47kg/mm spring. I have been struggling with finding a conversion rate between the two that makes complete sense but from what I understand the conversion should work out to around 4.7 n/m give or take. Can anyone help confirm that? As an additional reference the JBI calculator matched me to 5.0 n/m fork spring and a 64 n/m shock spring.
Racetech Spring rates are to be used with their valving, which doesnt make a ton of sense. Call a local tuner or big shop and ask for their recommendation for stock valving
I am about the same weight and have a 27 model, it's an updated model but i believe they still have the same spring rates.
I went up from 54nm to 56nm in the rear and put one 5.0nm in one side of the forks and im pretty happy with that. I will probably put both 5.0's in the forks and try that though cos I feel it is a little soft still. I'm happy with the rear but.
For reference I'm Vet B speed and just ride moto, I also prefer my suspension on the softer plusher side.
Race Tech usually compensates with higher oil volume in the fork, that would explain a lighter than expected spring rate.
Valving is important too, especially when changing spring rates by a few sizes.
Unfortunately, there is no one size fits all when it comes to spring rates. I find that a person can have up to 3 “correct” spring rates on paper, but so much of it comes down to an individual riders preference, height (leverage plays a big part on the shock spring rate) as well as the valving and oil height specifications. I also am of the opinion that someone’s ability/skill doesn’t have as big of an influence on spring rate as most think.
Regardless, given you are 220, I would defiantly expect you to be going up on spring rates. Are you going to just change springs and leave the stock valving or have a tuner give you a full setup?
If you are getting a full setup done, I would just go with their recommendation. And if they don’t recommend a spring rate change at all, I would find a new tuner.
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I have not spoken with a tuner yet. I was hoping to just DIY a rate change, call it a day and then after a few more rides revisit valving if I felt the need. I’m starting to wonder if I am better off just going through a tuner from the very beginning.
When you start going to heavier springs rates, you need more rebound damping. You might be able to get away with just slowing down your rebound with clicker adjustments, but clicker changes aren’t as effective as valving changes.
It would be a shame to change springs rates, ride the bike and still not be happy, go to a tuner and have to pay for another set of springs to suit the tuners specs. I think going to a tuner is the better option.
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