Posts
23
Joined
3/20/2025
Location
Atlanta, GA
US
Just double checked my rider sag and it’s right around 105mm using a sag scale. The static sag is at 47mm… The bike has the stock spring (42N/mm), and I weigh 166lbs without gear. I plugged the #s into the racetech calculator, and my weight is pretty much spot on for the spring. Any idea what could be going on for my static sag # to be so high with the right spring rate and race sag?
Might be time for a suspension service..
How much preload, how long is the spring when it's on the bike with it on a stand?
You need to measure the spring, can't tell anything from that picture.
9 & 3/16” ; 23.4cm
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
That's ~6mm preload, normal.
I would service the shock if you have more than 30h on it.
Unless measurement is wrong/off, something is not right. Did you measure several times? Sometimes the scale can move when moving bike up and down on the stand.
I’m definitely overdue for a service then. I’ll try to get it scheduled. I’ve been wanting to get the forks revalved anyway. I’m 99% sure the measurements are good, but I’ll check one more time.
Potentially chain binding or linkage drag. Might have some rusty or gritty bearings. These bikes need a crap ton of chain slack to prevent binding. I've found 70mm from the swingarm just behind the chain slider to be ideal.
Wouldn’t chain binding cause the static sag to be less than it’s supposed to be, not more? I got a lot of chain slap my first time riding, so I adjusted the slack to the higher end of the manual spec.
I’ve been riding trails with small jumps, but I’m afraid to go to the actual track until my suspension is working right.
These bikes are really weird when it comes to chain slack. If you are anywhere in the recommended range, you are too tight. They need more slack than the recommended range. JBI has a whole video on YT explaining this. If you disconnect the shock and run the swingarm through it's stroke to obtain the optimal slack, you'll discover it is 70mm, as I did. Any tighter and it binds, any looser and you get excessive noisy slap.
Thanks. I will reset it to 70 and make sure it's not slapping. If you have any other tips for suspension set up, let me know. I'm going to take it out this weekend and drop it off to get the suspension rebuilt and revalved for my weight, class, and riding.
Were you able to get the stock forks working well with a revalve?
My bike is a 2025 FC350... so not really comparable. But I am happy with the stock valving for MX.
Double checked the measurement today.. Static sag is 100% 1-1.5 lines above 50, so it's way off. This is with the other measurements I told you being spot on, and the sag set with gear on around 105mm +-3mm. Definitely seems like something is wrong with the shock. Going to take to the shop this weekend for a rebuild and revalve front and rear. It's definitely overdue at 69 hours.
I'm going to get them to grease the linkage and headset bearings, replacing if needed.
Is there anything else I should get done during this service? I bought the bike from a guy (C class woods rider) who is a side by side mechanic, so he was on top of all the other maintenance items. Anything that doesn't involve opening the engine or suspension, I can do myself.
I am going to fill out a suspension form from one of the big companies and give it to my local KTM shop for revalve and set up.
Thanks for all the help.
Post a reply to: 2023 250 XC-F Sag #s Off?