Garage Files: How to Set Suspension Sag With Motool’s Slacker Digital Sag Scale

How to Set Suspension Sag With Motool’s Slacker Digital Sag Scale

If checking suspension sag isn’t a regular part of your bike maintenance routine, you’re missing a key component of performance. Determining proper sag—on an air or coil shock—can be difficult for several reasons.

Air shocks: Most new forks and air shocks come with an O-ring on the stanchion or shock shaft that can aid in sag setup, but this simple tool can often be awkward to access and decreases the likelihood of an accurate setting. Plus, what do you do when your O-ring becomes damaged or breaks?

Coil shocks: Measuring sag on a coil shock requires the help of a friend, and relying on a friend’s mechanical ability isn’t always wise.

Following the steps below, anyone can set his or her own sag. Using Motool’s Slacker Digital Sag Scale, you can take measurements and make adjustments accurately with no assistance required.

WHAT IS SAG?

Rider sag is the measurement of how much the fork and shock compress when you get on the bike. Setting the sag lets you change where in the range your suspension “sits” with you on board, and it gives the suspension an initial point to work from in either direction. Most mountain bike suspension systems require between 20- and 35-percent sag.

DETERMINE YOUR TARGET SAG

Target sag is a percentage of the bike’s total travel. Most bike manufacturers recommend target sag for each specific model, so be sure to check the owner’s manual for your specific bike’s range of sag; however, there are a few rough guidelines based on the type of bike and riding:

XC bikes (≤120mm travel): 20–30% sag

Trail/enduro bikes (120–170mm travel): 25–35% sag

Downhill/freeride bikes (≥170mm travel): 30–40% sag

SETTING SAG USING THE SLACKER TOOL

The process of calculating sag is the same for the fork or shock. Motool provides a fork adapter, as well as a seatpost adapter, to facilitate rear-shock setup.

SHOCK

1. Strap the seatpost adapter to the seatpost. Position the cable anchor pointing towards the rear axle.

2. Place the axle insert on the Slacker magnet.

3. Place the axle insert into the Allen bolt of the wheel’s axle.

4. Extend the retractable cable and connect it to the fork adapter or seatpost adapter. Be sure the main unit is free to rotate; it should spin a few degrees to match the retractable cable’s angle.

5. Strap the remote display to the handlebars using the Velcro strap.

6. Connect the remote cable to the main unit. Route the cable so it won’t get caught in the tires or drivetrain.

7. Connect the remote cable to the remote display. Once connected, the unit will automatically boot up, and the digital readout of the remote display and main unit will turn on.

8. Get on your bike. Notice you can bounce up and down on the suspension, and the number on the digital readouts of the remote display and main unit will fluctuate as you move. Now, stop moving. The number displayed once your body becomes stationary is your initial measurement.

9. Record your initial measurement. This will allow you to know where you started. Be sure to write down this number and use this as a baseline to make adjustments. Now, it is time to calculate your bike’s maximum travel.

AIR SHOCKS

10. Attach a shock pump and note the air pressure. (This will allow you to know where you started.)

11. With a shock pump attached to the air shock, remove all air using the shock pump’s bleed button.

12. Grabbing under the saddle, lift the rear wheel of the bike off the ground. Allow the rear wheel to drop/extend fully, and zero out by pushing the power button once.

13. Push on the saddle to bottom out the suspension. The number displayed is total travel; be sure to record this number (this only needs to be done once per bike).

14. Pump the shock pressure back to your initial measurement.

15. Get back on your bike—it’s measurement time: You are now calculating sag in real time using the Slacker tool.

The math equation to calculate the shock stroke needed to obtain your target sag is: Total Travel X Target Sag (%) = Shock Stroke. Have a calculator nearby to confirm that the Shock Stroke value shown on the Slacker tool’s digital readout equals your Target Sag calculation.

COIL SHOCKS

—Remove all preload, and bottom out the suspension. Note: It may be necessary to remove the spring and mount just the shock body.

—Grabbing under the saddle, lift the rear wheel of the bike off the ground.

—Allow the rear wheel to drop/extend fully and zero out by pushing the power button once.

—Push on the saddle to bottom out the suspension.

The number displayed is total travel. Be sure to record this number (this only needs to be done once per bike).

—Preload the shock spring back to its initial measurement.

Note: It may be necessary to replace the spring, if removed.

—It’s measurement time: You are now calculating sag in real time using the Slacker tool.

The math equation to calculate the shock stroke needed to obtain your target sag is: Total Travel X Target Sag (%) = Shock Stroke. Have a calculator nearby to confirm that the Shock Stroke value shown on the Slacker tool’s digital readout equals your Target Sag calculation.

FORK

1. Strap the fork adapter to the fork stanchion. Position the cable anchor pointing towards the front axle.

2. Place the axle insert on the Slacker magnet.

3. Place the axle insert into the Allen bolt of the wheel’s axle.

4. Extend the retractable cable and connect it to the fork adapter. Be sure the main unit is free to rotate to match the retractable cable’s angle.

5. Strap the remote display to the handlebars using the Velcro strap. Connect the remote cable to the main unit. Route the cable so it won’t get caught in the tires or front brake. Connect the remote cable to the remote display. Once connected, the unit will automatically boot up, and the digital readout of the remote display and main unit will turn on.

6. Get on your bike. Notice you can bounce up and down on the suspension, and the number on the digital readouts of the remote display and main unit will fluctuate as you move. Now, stop moving. The number displayed once your body becomes stationary is your initial measurement.

Now, it’s measurement time: You are now calculating sag in real time using the Slacker tool.

The math equation to calculate the shock stroke needed to obtain your target sag is: Total Travel X Target Sag (%) = Shock Stroke. Have a calculator nearby to confirm that the Shock Stroke value shown on the Slacker tool’s digital readout equals your Target Sag calculation.

THERE ARE SO MANY WAYS TO GET MOUNTAIN BIKE ACTION

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