Suspension Fundamentals & How to Make Adjustments
As suspension evolves and bikes & equipment become more sophisticated we've recognized the benefits of having a resource for folks to gain a better understanding of what terms mean and how to make adjustments around suspension.
If you have particular needs or would like help tuning your suspension we are happy to schedule a consult session....shoot us a note of give us a shout.
Low Speed Compression Damping: Controls the motion of the wheel moving upward (handlebars/saddle moving downward) over gentle changes in terrain and moderate impacts, and during climbing and braking. The low speed compression valve is an orifice(s) that can be adjusted via a shutter or like device.
High Speed Compression Damping: Controls the motion of the wheel moving upward (handlebars/saddle moving downward) during harsh impacts. On big hits when the oil can’t get through the low speed damper valve fast enough, the high speed compression damper, or blow-off valve, comes into play allowing the oil to bypass the low speed compression damper and flow through a more free-flowing valve. This valve also can be adjusted via a shutter or like device.
Rebound Damping: Controls the motion of the wheel moving downward (handlebars/saddle moving upward) returning toward home position.
Spring Rate: The rate at which the force increases while slowly compressing the fork or shock. This is controlled by air volume, or by coil spring stiffness. Reducing air volume by adding pucks or oil to the air chamber makes the air spring stiffer.
Static Sag: The amount that the fork compresses with the rider static on the bike in a “normal” riding position. Many riders set static sag in a standing “attack” position, as though they are riding a technical section or downhill. If you want your suspension optimized for a sitting and pedaling position, set static sag in this position. Static sag is controlled by adjusting air pressure or coil spring preload.
Review the manual to understand where the adjustment knobs or screws are located. Start by adjusting to factory recommended settings. Then fine tune using the procedure below.
Step 1. Set Static Sag: With compression damping at its lowest setting, use your suspension pump to adjust the air pressure (or adjust coil spring preload) until the static sag is 25% of the total travel. Make sure to push the suspension up and down a few times to balance the positive and negative air chambers before measuring. Some enduro riders like more sag, some xc riders like less sag. Not enough static sag and the fork won’t be able to extend to maintain contact with uneven ground. Too much static sag and the fork will be a little more difficult to bunny hop or manual over small objects.
Step 2. Adjust Rebound Damping: Push down on the bar or saddle and release quickly. The suspension should extend quickly to home position. If it clunks at the top of stroke, dial in another click of rebound damping. If it returns too slowly, remove a click of rebound damping. On fast and technical downhills if the front or rear end feels bouncy or “dolphins”, or kicks back when landing air, add a click of rebound damping. If it isn’t rebounding fast enough and feels dead when popping off jumps or tends to pack down over multiple bumps, remove a click of rebound damping.
Step 3. Set Low Speed Compression Damping: Adjust low speed compression damping so that the fork feels plush and supple. During climbing, or on technical sections and downhills, if the front end dives excessively during braking or the back end squats while climbing add a click of low speed compression damping. If it stays high in the travel and doesn’t feel supple enough, remove a click of low speed compression damping.
Step 4. Set High Speed Compression Damping: If the front wheel bounces off of sharp edged bumps, rocks, or logs, or jump landings feel harsh though you are not using full stroke, remove a click of high speed compression damping. If the front wheel is sucking up large hits too easily and blowing through full travel and bottoming, add a click of high speed compression damping.
Step 5. Set Spring Rate: Go for a ride of typical difficulty that you would normally ride, riding it as aggressively as you would normally ride it. You should come within 10mm of the full stroke of your suspension, or even bottom out lightly on the biggest feature or hardest hit.
- If you are not getting full stroke, and your compression damping is correctly adjusted, you need to reduce the spring rate. If you have an air spring you have to increase the air volume to make the spring softer. Check to see if there are any volume reducer pucks or oil in the air chamber. Remove a puck, or remove a cc of oil from the air chamber. If you have coil suspension replace the spring with a softer one. Now go back to Step 1 to reset static sag and continue through the process.
- If there are no pucks or oil in the air chamber, you can’t make the volume bigger to reduce the spring rate. Return to Step 3 and reduce the low speed compression damping. You will be trading fork dive for full travel, until you reach your threshold for fork dive. Continue through the process.
- If your fork is bottoming out too easily you need to increase the spring rate. If you have an air spring add a puck or a cc of oil to the air chamber to reduce the air volume to make the spring stiffer. If you have coil suspension replace the spring with a stiffer one. Now go back to Step 1 to reset static sag and continue through the process.
Step 6. Go for a ride. Now that you are more in tune with your suspension, take note of how the bike feels in various situations and make small adjustments until you have it dialed to your satisfaction. Keep in mind that spring rate adjustments and compression adjustments can both have a similar effect on overall suspension travel. The difference is that too much compression damping makes the fork feel harsh while limiting suspension travel. A fork with a high spring rate will also limit suspension travel, but will still feel plush if the compression damping is set right.