Different springs in each fork?

So I just resprung my 2012 crf250r (48mm showa forks), and the springs race tech recommended are too hard, I don't have enough front sag (64mm), I am wondering if I can run different springs in each fork?

A friend of mine who is a Moto GP mechanic said it would work fine and they do it all the time, but he hasn't spent much time on dirt bikes, so just want to make sure it won't cause any issues.

Won't make any difference. In fact if you want a specific rate it's sometimes easier to accomplish by using two different springs.

65 is enough for anything but really snotty rocks and ruts

I sent someone a odd fork spring for a ktm to mix with there origenal spring. They never sent there old one back.MOG. I bet it's because u see the price of the postage. Lol

65 is enough for anything but really snotty rocks and ruts


Ok, I should have mentioned, I ride a lot of rocks, and i'm rather tall and heavy. Race tech recommended a .55kg spring vs .45kg stock


I was actually fairly happy with the front end stock, but when I resprung the rear end it was a huge improvement, so I thought i'd redo the front as well, since it felt like I was riding a bit stinkbug.


So when I went to ride, it was so hard it was chattering my teeth, I rode yesterday for 3 hours and woke up this morning feeling like a truck ran me over. Basically turned my good bike into a turd.


I started with stock settings on the forks 7C/11R (whch was what I was running before), and ended up going full soft on everything, which made the bike a little softer at low speed but still jarred my teeth at higher speed/bigger hits


I'm thinking for rocky woods riding I need a bit more sag than an MX guy

Edited by mudguy

Yes up to 75mm but 65 is normally close , I think around 55 for mx and my own personal bikes have ran as little as 45mm and still cornered well

.45 to .55 is a HUGE jump. What do you weigh? I ride with a couple big boys and none have jumped that much, especially considering woods/rock use. I don't trust RT's calculator. 

6'4" and 250 + quite a bit of gear


I know the calculator is just a guess, that's why i'm looking at my sag numbers.


.45 + .54 should be approximately a .49 according to my friend, so i'm thinking that might put me in a better range. It also gives me quite a few options if I order a single spring later.

.45 to .55 is a HUGE jump. What do you weigh? I ride with a couple big boys and none have jumped that much, especially considering woods/rock use. I don't trust RT's calculator. 



What spring rates do your friends use?

I emailed race tech specifically about using springs that are widely mismatched, and this is the response they gave:


That is completely fine to do the new sff forks use only a spring on one side.
What's cool about this is if I buy an additional single 0.50 I will then have lots of rate options to choose from - .45, .475, .49, .52, .54

Did you already order your 5.0 spring that you are looking at?


I'd like you to shoot me an email before doing so to chris@racetech.com.


Along with trying to help you out on the new springs, I will make sure the techs are aware of your feedback on the calculator with this specific model.

mudguy, I sent your notes over to our head of R&D.  Here is the info he provided back:


Springs are linear so they shouldn’t cause that problem. Look for too much preload; should be around 3-5mm, or binding in forks on install of front wheel. I don’t know  the rider weight but sag numbers on the front typically are about 60mm, but sag on the front on a dirtbike is not so important; however, preload is.

Chris, thanks for your response, really cool you guys monitor TT.


All I did was swap from .45 to .54 springs, I had previously rebuilt the forks with new bushings and seals about 3 months ago, they had been working great so far. 


I don't understand how to measure preload on the forks, I just installed the springs without using the washers.


The problem was very similar to having bound up forks, I didn't feel very much dive when on the front brake, just felt stiff, so perhaps it was bound up, didn't really think about that. I am always very careful about installing the front axle, and I do the honda trick of banging the wheel back and forth which seems to work OK, but I guess it is possible I had them tweaked. I'm running a 450R front rim/axle right now so maybe something is up with that axle.


I have since changed one of the forks springs back to stock and it definitely is working a lot better, maybe i'll put the .54 back in this weekend and try again.


I just bought the RT suspension bible, cool book, looking forward to reading it the next few days.

Excellent, just shoot me an email or give our tech support line a call if you have any questions or want to investigate a bit further as you get some more time into it.

I got it all sorted out, my forks were bound up which caused my problem. also had to harden rebound 3 clicks, now the bike handles great.

The race tech suspension bible is great, I finally have a clear idea of how my suspension is working.

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