Spring selection?

26 replies to this topic
  • PK

Posted September 30, 2001 - 05:34 PM


I am wondering what everyone else is running for fork springs and rear shock springs. I weigh 215 lbs and the springs on both the front and rear are stock. After a motocross race today I can seee where my rear tire is hitting the fender and the fork tubes show evidence of bottoming as do my wrists. RG3 did my suspension originally and said I wouldn't need to change my springs but I think I am at the point now where I need to ante the springs a little bit. I run my fork fluid 10 mm higher than stock and I run 100 mm of sag in the rear. Any suggestions?

99 YZ400

  • Boit

Posted September 30, 2001 - 06:40 PM


Do you think you've improved enough to the degree that you are riding much more aggressively than 2 or 3 months ago? Perhaps at the time RG3 did your suspension, your talent was a bit less developed than it is now. I would contact RG3 again and repeat to them what you've posted here. My first thoughts are that you are indeed in need of the next stiffer spring rates. You will probably need a revalve to match the stiffer spring rates.

[This message has been edited by Boit (edited September 30, 2001).]

  • jaybird67k

Posted October 01, 2001 - 07:37 AM


Boit is right, the more aggressive you ride the stiffer you will want the bike.
I had my suspension done and had it stiffened up a bunch on the low speed compression, I run 95mm of sag and weigh 155lbs and I am going to have my suspension re-valved again to stiffen it more.
At 215lbs you definately need yours stiffer for MX, like I said I weigh 155lbs and am at the point of considering stiffer springs front and rear.

Later, Jason

  • Taffy

Posted October 01, 2001 - 10:33 AM


try running your sag at 90-95mm


  • DaveJ

Posted October 01, 2001 - 10:46 AM



I'm 165 (without gear) and I'm running a 5.6 rear and .47 front. For the trail it's great. For the big tracks, I think I could go up one more. Maybe more so on the front.

Your weight, speed, and terrain are the three things to consider.

I also run 7 to 10mm of preload on the front (depending on my day) and set sag at 110 to 120.

Hope this helps.


  • MX_Tuner

Posted October 01, 2001 - 04:19 PM


You guys are great. Thinking the spring is what keeps it from bottoming....

Good laugh guys. Keep up the humorous posts.

And to think, I almost thought you were serious......

Think of this concept. The spring helps dictate ride height. The damping controls the speed at which compression (or rebound) occurs.

I don't make this stuff up.

MX Tuner

  • Boit

Posted October 01, 2001 - 09:40 PM


Your skills in sarcasm are pretty impressive.

  • yzernie

Posted October 01, 2001 - 10:24 PM


MX Tuner,

You are partially correct. If you think that springs have nothing to do with the action of the forks other than ride height, you are sadly mistaken.

Smoke another joint and come back after your next set. :)


--Life is too short, work hard...play hard--
Sponsored by Yamaha of Cucamonga, Larry Roeseler's Stroker Fourstroke Speed Equipment and Answer Racing

  • Scooter426

Posted October 02, 2001 - 05:19 AM


Maybe straight rate springs and progressive wound springs set ride height more progressively or ...uuhhhhh... straighter.

  • DaveJ

Posted October 02, 2001 - 09:34 PM


When a bike is not moving, spring weight and pre-load determine height. Call it static height.

When a bike is moving, the valving does nothing but attempt to maintain static height. In other words, in controls oscillation.

When a bike bottoms, it's an event where spring and valving is over taken when the force of weight and inertia is applied. Stiffer springs will contribute to bottoming resistance, as will a more progressive valve configuration.

So when a bike bottoms, do you get stiffer springs or do you modify the valving?

For motocross configurations, (not FMX) spring selection and pre-load should be determined by setting static ride height with rider and gear in place, (not by whether you bottom or not). This static ride height is also a calculation for maintaining balance in the bike during riding. I.e., if the front end feels light, you can raise the pre-load on the rear, and vice-versa.

With balance in place, absorption becomes the responsibility of the valving. In other words, if you bottom with the proper spring in place, you need more aggressive valving.

More specifically, springs are determined by weight, valving is determined by weight shift, (read that again). And, in general, the more spring you have, the more valving you have to run.

Can valving affect ride height and balance? The answer is yes. Since valving attempts to keep the spring around a fixed point, the tighter the valving, the less deviation from this point. Hard valving (for lack of a better description) in the front with soft valving in the rear will result in bike that wants to ride high in the front when the suspension is being used, say over a set of whoops.

Between the variables of spring rate, pre-load, fork height, rake, linkage arms lengths, rebound and compression valving (oil, stacks, pistons…etc), and tire pressure, how does one know what to change to optimize the ride quality or resolve problems?

That’s the question the factory teams pay big bucks for, of which I may be able to provide some crude answers for. A later thread, unless someone wants to take it from here.


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  • PK

Posted October 02, 2001 - 03:09 PM


Thanks for the replies, even you MX Tuner. You made a point I would think most of us already knew but for those who don't, he is correct, the valving adjustments are a major factor in whether the bikes bottom or not. My post was not on what to set the clickers at, it was to get a feel for what springs people were selecting for there bikes. I have gone up in weight since I revalved my forks and shock, as I had just recovered from 2 broken wrists while racing at Hangtown. I'll give RG3 a call and see what they say and most likely go up a size or two on my springs depending what the guys at RG3 have to say.

Thanks to all,

  • MX_Tuner

Posted October 02, 2001 - 04:24 PM


That's exactly my point. Springs have a very definite job. But going to stiffer springs to control bottoming is a band-aid fix for most of the guys who do it. The magazines have brainwashed a huge number of riders into thinking that they must go stiffer to achieve any quality of ride. Nothing could be further from the truth. Unless I have a rider who is significantly over the rating truly necessary for getting the correct ride height, I rarely go with stiffer springs. When I do a revalve and someone questions why I don't recommend stiffer springs, I tell them if they aren't happy with the way I've done their suspension, I'll install the springs for just the cost of the springs. I've never had anyone not happy with the spring rates I recommend.

Another thing to think about. A bikes turning ability (for lack of a better term) is determined, in part (and a big one at that), by the steering head angle. The steeper the angle (straighter up and down, like a tricycle), the quicker the bike will turn. When you adjust the fork height in the triple clamps, you're actually altering the steering head angle slightly. That's why when you raise the forks, the bike steers quicker and turns in easier. When you go into a corner, as you begin slowing, the front end drops in its stroke. The more it drops, the quicker it will turn. If it didn't drop at all, your bike would steer like $hit, pushing the front end. When you install stiffer springs, this prevents the front end dropping down as much as it could. This also hurts the bikes ability to corner. Does this sound familiar to some of you?!?!?

What this means is there are better ways to control bottoming. Some guys like to use bottoming cones. Personally, I haven't had to resort to using them. I prefer to run a very high oil level. This acts as a progressive, position sensitive spring that will still let the front drop down enough to give great turning. This helps with bottoming resistance but still lets the front be as plush as possible.

DaveJ, very nice explanation on valving vs spring selection. You get an "A".

And for those who don't like the sarcasm, I've never been accused of being too nice. If you want it sugar coated, go to Dunkin Donuts. We're grown ups here. Lets act like it.

MX Tuner

  • motoman393

Posted October 02, 2001 - 05:36 PM


All this suspension talk is making me hungry for Dunkin' Donuts! LOL @ MX Tuner


I get my kicks on a 426!
Motoman393's MX Site

  • Boit

Posted October 02, 2001 - 08:10 PM


MXTuner: Let me get this straight. By being sarcastic and insulting, YOU are acting like a "grown-up"? Obviously, tact and diplomacy mean nothing to you. Does being a jerk come naturally to you or is it something you put effort into? Careful, trick question.

  • Taffy

Posted October 02, 2001 - 11:51 PM


MX tuner

calm down!

it's not that you're right or wrong it's that you talk down at people. people shouldn't be afraid to ask or be made to look a fool because they don't know.

you could have packaged what you said so many better ways than you did.

i'm sure many of the blokes here have visited the Yahoo site and spotted how it has been driven into the ground by someone who shall remain completely nameless.

the man asked about spring rates for his weight and we all chipped in with our idea's. you've pointed out that the valving is vital so good on ya and ta fanku. you were right.


  • J_Bone

Posted October 03, 2001 - 06:34 AM


Originally posted by MX Tuner:
You guys are great. Thinking the spring is what keeps it from bottoming....

Good laugh guys. Keep up the humorous posts.

And to think, I almost thought you were serious......

Think of this concept. The spring helps dictate ride height. The damping controls the speed at which compression (or rebound) occurs.

I don't make this stuff up.

MX Tuner, your knowledge in setting up suspension is exactly what I was taught, but your post is more child like than a GROWN UP! I agree with you Taffy!

Now I'm 200lbs. and I'm still running stock springs, but have adjusted the valves and settings for my riding style.

  • Ga426owner

Posted October 03, 2001 - 07:51 AM


I have to say that after reading MX Tuner's thread several times, I do not see why you all are so sensitive. I personally am tired of all the "Sugar Coating" that goes on in the Magazines & all the so called Moto experts that seem to know a lot about nothing. Talk about uncalled for: YZ Ernie's comment to MX Tuner to go smoke a joint.
The problem here is that most of you think you are the "Experts". Some of you may be. I think there are about 4-5 experts that regularly post pertinent info here on this site. The rest of you use this forum to gain info that you do not have the answers for. Some of you think you know a lot. You may. But in the suspension science world most of you are just like me, someone that wants to learn. So, stop with your stupidity & jackass comments & read/absorb what the experts or professionals have to say. You might learn something other than Fork Springs will cure my fork issues. Grow up or go to DirtRider.net or some other site. Some of you have been drinking too much ATF & sniffing 112 octane exhaust!!!!

  • MX_Tuner

Posted October 03, 2001 - 02:57 PM


First things first. I apologize if I came off a bit harsh. I just got back from the Vegas to Reno race and had to deal with mental midgets that made my job that much harder. The Thing one hopes for in a race like that is for it to be totally uneventful. That is, nothing going wrong, nothing exciting, nothing to do except dump gas all day long. And if certain individuals had done as they were instructed, it would have made my trip much easier. Apparently, the thing that happened is the things I asked to be done before I got there (couldn't get there any earlier than the day before the race) were taken as suggestions. They were NOT intended to be up for discussion.

I deal with guys all too often who don't want to listen to what I say and it makes my job much harder. Wanting certain things done to their bikes "because the mags say it needs it". Then I have to spend the next 20 minutes trying to convince them otherwise.

My point is I have two kids (5 and 8 years old) and I don't need to babysit anyone else. I don't need to spend time convincing anyone of anything. I get sick of having to talk people into doing something to help their bike. I come here to learn something and to try to help others with some of what I have experienced. You'll notice I don't reply to things I have little experience with. I *DO* reply to thing that I have found I am familiar with. I try to post with a style that will get someones attention and says I'm not just typing to hear the keys move. I don't have a lot of time to come here and beat around the bush. I get static from my wife for the time that I do spend here. I like to read posts to learn something. I'm under the strong impression that many others are here for the same reason. If you want tact, read Ann Landers. You want info? If I post something, you can count on what I've found to be true. I don't just play with one WR. I have quite a following and work on a slew of different bikes, two and four stroke. I had a shop. Guess what- that life sucked. Working 70+ hours a week ain't for me.

I'm trying to be helpful to those asking for some insight. If you don't like my style (or lack of it), fine. Don't read my posts. Like I said previously, I don't try to win any nice awards. I say what I feel. Ask anyone who has ever met me. I don't have a different personality here than I do in real life. What you see is what you get.

So, Boit, to answer your question, I have being an arrogant jerk down to a science. It's second nature.

MX Tuner

[This message has been edited by MX Tuner (edited October 03, 2001).]

  • Boit

Posted October 04, 2001 - 02:16 PM


Dave J: What would be the advantage. . . or difference of setting sag at 110-120mm over the typical 95-100mm? If I were to increase my sag to what you run and make no other changes, what would I notice once I hit the track? I'm getting a tendency to having the rear kick to the right side if I stand while launching a fairly simple double jump. If I seat-bounce, I don't get the kick.

MX-Tuner; if you'd like to throw in your two cents, I'll buy ya a donut.

  • DaveJ

Posted October 04, 2001 - 03:20 PM



My 110 to 120mm sag setting is particular to both my preference and bike set-up. In other words, it's only one part of the big set-up picture. What works for me may not work for others.

With that little disclaimer aside, setting sag, or better put, "pre-load" is a factor of setting up balance in the bike. If the bike rides high in the rear, more weight is placed on the front wheel, less on the rear. Vice-versa. Less weight on the rear means more rear wheel slide.

And by "balance" I'm essentially talking about the distribution of load against each wheel in a corner. Much like tuning a car for over or under steer characteristics.

So why would a bike kick high in the rear when you launch a jump?

One possibility is just this - too much balance bias towards the front. The bike is essentially weighing down on the front wheel before your launch, and following suit while in the air.

The fix. Lower the forks down in the triple clamps, (make the front taller) or remove rear pre-load.

The other possibility is that you don't have enough rebound or compression set on the rear. Not enough compression causes the spring to overload at the base of the ramp, then un-load while leaving the ramp. Same effect with rebound, but in this case, the load is not excessive, it's the un-load that is too rapid.

Have someone watch or video your bike on the jumps and note the position of travel in the rear. If it's maintained, then change pre-load. If it overloaded, increase (add) compression. If it's unloading before you take off, (that will be hard to see without slow motion) then increase (add) rebound.

One other issue is if you're letting off on the throttle shortly before takeoff, or in the air, but I'll set that aside.



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