Tech Tips: Setting Sag 14

Get some quick tips on how to properly set the rear sag on your bike.

If you're looking for the tools to help you do the job, jump on Chaparral-Racing.com.

Currently on sale at Chaparral: Motion Pro Folding Sag Scale.

Vital MX review on the Motool Slacker Digital Sag Scale.

Transcribed Version: 

Michael: "Hey, this is Michael Lindsay from Vital MX. We're at Chaparral Motorsports today and we're talking about setting up your rear sag. Lot of us spend good money getting our bikes just how we like 'em, especially in the suspension department, why not do what it takes to maintain that feel you're looking for? Before we actually get into showing you how to set the sag, we're gonna chat here with Larry Brooks a little bit about what sag means. A lotta people just see it as one number, but he's gonna give us some insight on what the numbers actually mean and how they relate to setup."

Larry: "As far as sag, I mean, you're pretty much setting up the balance of the bike. Each rider's a little bit different, obviously weight is different on each rider and you'd wanna set the bike up kinda how the rider wants it. I mean, they could set it up at 95 and want it to steer really fast or set it up at 105 and make it a little more sacked out in the back and steer long. Really, you're just changing the front end, the way the bike steers and the balance of the bike when you're putting more preload or less sag, let's say, and more sag. Everyone's a little bit different, they all kinda choose or go a different direction, but the average rider would set his bike up with about 100 to 105, that's safe and you could probably get a lotta riding out of it with a lotta comfort."

Michael: "So now we're gonna jump right into the sag. There're gonna be two tools you're gonna need for sure. You're gonna need your hammer and a punch to break loose your lock rings, unless you have a K10, which you'll need an Allen wrench to break lose the lock ring collar. For measuring tools, you're gonna either need a tape measure, or sag scale, or even a digital scale. First measuring tool we're gonna use here is our tape measure. We've got a little black line we've marked on the fender with a Sharpie and we're gonna meet that with the graphics line to judge our number, and this is gonna be our reference point. Right now we have 621 millimeters of free sag, this is unloaded, with nobody on the bike, with the bike on the stand. You're gonna wanna memorize this number as you're gonna subtract your next number from this. Three key things when you're setting sag. If possible, it's great to have a third person to help you to hold the rider up so he can get all his weight on the bike. Number two, need to try to get the bike on level ground. If you do it on incline or a decline, it's gonna affect the number. Number three, for the rider, he needs to concentrate as much as possible on being in the same spot each time. If forward or back an inch or two, it's gonna affect the number.

Now that we have the rider on the bike, we're gonna measure again. Using the same point as we did last time, we now have a number of 514. This equates to a sag number of 107 millimeters. This is in the range of what most people would probably consider acceptable. As we talked to Larry about, there's definitely some playing with the numbers you gotta do if you're a rider, if you're kinda searching for that feel. But I think some of the most common numbers you'll see is anywhere from a hundred to even 110, especially with some of the modern chassis being a little bit higher in the rear than they've been in the past, you start to see a little bit higher number.

So now we're gonna go for that target goal of 105 millimeters. So we need to break loose the preload ring so we can start changing the preload. There are two preload rings on top of each other in here. You wanna break loose the top one so you can spin the bottom and the shock. So, need to give it a tap here with the punch and a hammer to knock it counterclockwise to loosen it. Once it's broke loose, there's usually enough room on most bikes to be able to reach in there and kinda work it with your hand now a little bit. So now that we have that top preload ring broken loose, you can...on most bikes, you can get your hands in here and start to turn the spring. Right now, we're looking for 105 millimeter sag, which is 2 millimeters up from our past number. So to get that, we actually need to crank down on this spring. We need to go clockwise and put more preload on the spring to bring the rear end up. So around roughly one turn equates to around three millimeters for most spring rates, so we're gonna try to give it just about a turn before we check the number again. 

Now that we have our rider back on the bike, we're gonna check the number again. We're now at 516 millimeters of sag, so we've hit our target goal of 105 millimeters. Now that we've achieved the sag number we're looking for, we need to lock back down the preload ring, so kinda get your hand here and just spin it clockwise until it's snug and take your punch and give it a few taps and tighten it back up.  So another common tool for measuring you'll find in quite a few people's tool box is a sag scale. It's pretty simple, really, it's just a tall metal bar with numbers on it and you have a pin you put in your axle and then you measure up and set it at zero on whatever your reference point is gonna be on your rear fender. Once it's set at zero, you have the rider sit on the bike as you normally would and it compresses, and you match up the number on the scale. So if it corresponds to 105, then you have 105 millimeters of sag. 

The first two methods of measurement we've shown you requires some help. If you're on your own and you still need to set your sag, you can also check out the Slacker by Motool. If you want more info on it and to check out some more tech tips, jump on VitalMX.com."

Credit: Joe Carlino

C50_profile_1424660203 ML512 4/2/2015 9:03 AM

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14 comments newest first

Can you make these tech tips downloadable? I don't have internet access in my garage but would like to take the video out there with me as I do this procedure. Thanks

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Hi ML512: any update on being able to download the videos for offline use?

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fully agree mini elsinore. i really like ml512s reviews,tests,etc. i honestly think its him and keefer on top of this field.they are not trying to bro down or bs. just honest and realistic. with the trick bikes larry brooks is making,these videos should be great.

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Mini Elsinore and smoothies; Thanks, the feedback is greatly appreciated. We'll keep plugging away on what the users like!

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Thanks, that's the plan! We're going to try to jump through a wide range of topics. Look for the videos during the first week of every month.

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