Rear Shock Setup - '05 RM125

Ok, I am going crazy trying to get my rear shock setup correctly. I have just about tried every different spring on the planet but still cannot get the correct static and race sag..

So I need some help here. If someone with a 04 - 06 RM125 can please post there details eg. weight, rear spring etc and if someone can PLEASE post there measurements they get when measuring the bike on a stand with the back wheel off the ground, also the measurement you get when bike is standing on ground by itself and then also when rider is sitting on the bike. Please also let me know from where to where you are measuring...

All help will be much appreciated!

After setting your race sag how much free sag do you have?

I’m having the same problem with my 05 RM250. The stock 5.2 spring with my 165 pounds on the bike and a race sag of 99mm I had 38mm of free sag.

So that told me the spring was too hard for me and then I knew why the rear never felt right.

Ok so then I felt I needed to try a 5.0 spring but to see what racetechs spring calculator said even more made me feel that a 5.0 was my choice for my weight.

I tried the 5.0 and with my sag set at 99mm I had 32mm of free sag. I would like to have 25-30mm but if I go any softer of a spring I think the rear would feel under sprung so it seems the late RMs have funny linkage ratios.

I have found that when it is difficult to get consistant measurements for sag it is time (past due) to service your swingarm and linkage bearings. Most likely they will have to be replaced. There should be only a 2 mm difference (variance).


Lol yeah all tight on my end. I always maintain my bike. I hate rear end jingle.

"There should be only a 2 mm difference" ?? If you’re talking about rear end play? That’s way over due for my picky ass.

If you’re talking about sticktion then yeah 2mm-4mm is about right all depending on the age of the shock. A fresh rebuilt shock might be on the higher end for a very short time.

I get similar results when calculating my free sag. I cant get my race sag to anywhere near 100mm, the closest I can get is 85mm and then I get a free sag of 38mm. I have tried a heavier spring and same problem, hell I have tried a 4.4, 4.6 and a 4.9 spring. I have just redone all the linkage bearings etc and still same problem. So I serviced the rear shock, new shock oil and new nitrogen gas.... same problem. I will be getting a Ohlins rear shock today and hope it helps!

Whoohh thats bad. How much do you weight again?

I weigh in at around 160 pounds. My weight should be almost perfect for standard shock spring. I have a 4.9 (5.0 Std) at the moment and I get 80mm rider sag and then about 25mm static sag. Could still go a little softer. I managed to pick up a Ohlins shock for a great price and will pop it in sometime this week and see what how it goes from there...

i would still set the race sag before before checking the static

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