# Will shortening the shock require stiffer springs?

I want to do this to reduce seat height, so I plan to run the same sag as stock. The way I see it is shortening the shock (I'm looking at 1.5-2" overall rear travel reduction) is bascially the same effect as increasing sag (but the spacer takes out the the extra sag). Therefore the spring would then be way to soft, same as running 2" more than the stock sag. Is this right?

Stock sag is 1/4 i 1/3 of the suspension travel. So if your lowering it id just set the sag at 1/4-1/3 of that which will be more like 70-90 instead of 90-110.

And for your question kinda but no. Sag can be ajusted by preload, it doesnt have much to do with the weight of the spring. You can make a kx85 or a kx65 spring have the same sag as kx250 spring if you put a ton of preload on it

I lowered my DRZ by 1 1/2", never could get it to ride right. I got a stiffer spring and it's a lot better now. You shouldn't need to go up a lot if the stock spring rate is correct for you. At full length, stock was good for me, but I went from the stock 5.3 to a 5.5Kg for the reduced travel. Definitely stiffer springs in the forks though, I went from .44 to .47Kg. (I weigh 180lbs and ride rough terrain)

If you really want to know, here is one way to calculate the shock spring rate when lowering a bike. It is pretty generic and will need to be tweaked for each application.

Normally when we give this information out, well you know the saying. But this time we'll let you live.

1. the formula

spring rate = ((wt bike + rider) x 1.40 x flr) / shaft travel

where flr = final leverage ratio

flr = wheel travel / shaft travel

2. wt bike + rider

wt bike = 240

wt rider = 180

wt bike + rider = 420

wt bike in kg = 191

3. flr at original travel

wheel = 305mm

shaft = 125mm

flr = 305 / 125 = 2.44

4. flr at lower travel

lower the bike 1.0 inch (25mm)

some guess work is needed. we need to know the initial lev ratio.

we will estimate the initial lev ratio to be 3.00

here we go:

wheel = 305mm - 25mm = 280mm

shaft = 125 - 8 = 117mm

shaft is reduced by 8mm because: 25 / 3 = 8

(25 wheel reduction / initial lev ratio)

therefore, the lowered numbers are:

wheel = 280mm

shaft = 117mm

flr = 267 / 117 = 2.39

5. so we have the flr for both the stock seat height and the lowered seat height:

stock seat ht = 2.44 flr

lowered seat ht = 2.39 flr

6. plugging in the numbers

stock spring rate = (191 x 1.40 x 2.44) / 1.25 = 5.22

lowered spring rate = (191 x 1.40 x 2.39) / 1.17 = 5.47

Or: if you lower the bike and try to use the same spring, simple reasoning tells you that the stock setup had a 5.2 spring that was compressing 125mm at full bottom. now you have the same spring trying to control the same bottoming force and it only compresses 117mm. therefore, with the lowered setup, the shock bottoms before it reaches the same tension on the spring.

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Thanks! My next question would be how to figure out the new spring rate but I think you covered that too. FWIW I'm right at the upper end in weight for the stock spring. I think the way to tell is to set the sag right now at stock + 2" which would be the same preload when shortened which I know right now will be way too soft.

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• Hey guys, I'm wondering what suspension settings you all are running front and rear?  I have a 2017 crf 250r I'm a 210lb newer rider, my settings are currently set at,
rear suspension low speed  at 12 clicks
rear suspension high speed 2 turns
rebound is 12 clicks.
Left front fork inner chamber 150psi, outer  chamber 10psi, balance pressure 150psi
Right front fork compression position 7 clicks, rebound 29 clicks
Sag is 4"
Thanks guys

• One of the most common calls we get here at the shop is “how do you recommend I go about tuning my suspension?” Good question! The second most common call is “I started turning clickers on the front/back/bottom/top etc. and now I don’t know what I did, help!” The amount of improvement you can gain from proper suspension setup is significant, if you go about it in the right way.
Look at it this way: if you are 6ft. tall and get in your truck after your 5 ft. 3in. wife just drove it, the first thing you are going to do is adjust the seat/steering wheel, etc. for your size. The same thing goes for your bike’s suspension-last week we had (3) 2010 bikes in the shop for revalves at the same time. Identical models, one guy was a 150lbs. pro racing MX, the next guy was a “B” level GNCC racer and weighed 220, and the third guy was a 180lbs. trail rider. Same bike, three totally different setups!
So with that in mind, here is where to start:
• Grab your owners manual, a computer, clipboard and a scale. You cannot effectively start tuning until you determine if the correct springs (fork and shock) are on the bike for your weight. Put down the double cheeseburger, hop on the scale, and get your weight in street clothes. Add in for your gear, which typically runs between 20-30lbs. You can easily check recommended spring rates by visiting www.racetech.com under their spring rate calculator. Look in your manual (or ask your tuner) and see what rates are on the bike.
• If you need to change spring rates-do it first. Trust me on this, trying to tune suspension with the wrong rates is not only frustrating, but you will be short changing yourself on the results. On most bikes the shock spring is easily changed, fork springs can be a bit more difficult-get qualified help if you need it.
• Even if you are familiar with what “clickers” are, take a moment and read your manual. Determine what style of forks you have (closed cartridge or open cartridge), where the compression and rebound clickers are, and check to see if your shock has both a high speed and low speed compression adjustment.
• Grab the right tools to adjust, load up and go find a typical piece of terrain to test on. By typical I mean your MX track, hare scrambles course or favorite singletrack. You don’t need to ride a 30 mile loop in order to adjust your bike, rather focus on finding a section of track/trail that has all the different types of jumps/bumps/whoops you encounter.
• OK here is where I will preach a bit-everybody has a buddy or two that claims to “know suspension” and setup. This is YOUR bike, and unless you plan on dragging him around on the back of the seat the end result of your tuning should be focused on what feels good to YOU. Trust the feedback the bike gives you…..
• If you do not have an idea of where to set your clickers, put them in the middle of their adjustment range. This is your baseline setting.
• Gear up and get warmed up. It is important to be loosened up on the bike BEFORE you start tuning, or you run the chance of mis-diagnosing how the bike is feeling (I never start testing until I have at least 15-20 minutes of warmup time on the bike-I always ride stiff initially and sometimes do not get into a groove until then). Some guys can just jump on and pin the damn thing right from the truck. You know who you are, Wattsy……
• Remember, this is a tuning session not the MXoN. Use you head and ride at a pace UNDER you max speed-there will be plenty of time to “fang it” once you have zeroed in on some good settings.
• OK-ride and get a good feel for the bike with the clickers in the middle of their range. Now it’s time to really find out what “too soft” and “too hard” means.
• Take your clickers and turn them all the way out, full soft. Go ride the bike, but take it easy-it will feel ALOT different. Then come back in and turn everything all the way stiff-go ride again, being careful as this will feel totally different again. For guys that have tuned a bit, these two steps might seem pretty basic, but you will be amazed at the difference in how the bike feels. This is especially helpful for guys who are just starting out.
• Set everything back to baseline. FROM THIS POINT ON YOU WILL ONLY MAKE ONE ADJUSTMENT AT A TIME!!!!!!
• So now you will want to determine your tuning range. The tuning range is what settings you will use to adjust for different conditions. For example, If you are an MX racer as well as an occasional singletrack rider you will want to use different settings for those conditions.
• Fork compression is a good place to start. Ride your test section at baseline, then go about 3 clicks softer. The question to ask yourself after each adjustment is: Does it feel BETTER, WORSE, or THE SAME????
• There are no right and wrong answers, only what you feel. So let's assume that the 3 clicks softer felt better-go 3 more clicks softer each time until it does not feel as good. You have just found the soft end of your fork compression tuning range. Now return to baseline and do the same thing, only this time go stiffer. After you have found the best compression setting, work on rebound. Remember, one adjustment at a time ONLY or you can become confused!!! Do the same testing with your shock. Once you have both comp and rebound individually adjusted, you can fine tune them to work together-just make one adjustment at a time!
• As a final test, when you have what you would consider your best setup, write it down, then go back and compare that to your initial baseline, riding both setups back to back. Might surprise you…….
I could go into some advanced tuning topics about the interrelation of compression/rebound, high and low speed comp, tuning for extremes, etc. but we will save that for another newsletter. Take your time, tune by how your bike feels to you and have fun. You will be surprised by how much better you will ride with well adjusted suspension.