You’ve taken a great first step in purchasing a full-suspension E-mountain bike! To get the best performance from your new bike, you’ll want to fine-tune the front and rear suspension components. Full-suspension helps you roll over technical terrain with less effort and it gives you more traction on rough or loose surfaces compared to a hardtail. The suspension setups for Giant off-road E-bikes are the same as those on traditional mountain bikes.
Let’s begin with some suspension terminology:
Travel: The amount movement your suspension has or, in other words, the length of the stroke of your suspension. For example, the Full-E+ has 140mm of rear-wheel travel and the Dirt-E+ has 120mm of front-wheel travel.
Fork: The front suspension mechanism on your E-mountain bike.
Shock: The rear suspension mechanism on your E-mountain bike.
Stanchion: The tube(s) of the fork or shock that goes into the “lowers” on the fork and the body of the shock.
O-ring: A rubber ring around the fork or shock stanchion that is used to measure the sag.
Sag: Compression of the fork and/or shock caused by the rider’s static weight. Performing a sag test is how you set the air pressure in your fork or shock. Ideally, you want to set your sag at about 25-35% of the total travel.
Spring Rate: The amount of force required to compress the spring. This can be the air pressure in the shock or the spring rate of the coil.
Compression Damping: Some forks and shocks have the option to control the flow of oil in the internals of your suspension. The more compression damping you use, the firmer the shock or fork will feel.
Rebound Damping: The rebound adjustment controls the speed at which your fork or shock returns to natural position. The more rebound damping you use, the slower the fork or shock will return to its natural position.
How to Set Sag on a E-Mountain Bike
To set your suspension in a proper way, you need some tools to get the best results out of your suspension.
- Shock Pump: The device you use to pump air into your shock and fork. Because of the high pressure that goes into the fork or shock, your regular bike tire pump won’t work.
- Ruler: To measure the neutral and suspended length.
- Note Book: Write down the base / initial settings of the fork and shock. This way you can always go back to the settings you came from.
- Make sure your tires are inflated correctly and you are wearing all your riding gear.
- Sit down on your E-mountain bike and have a friend stabilize the front of your bike with your front wheel between their legs and their hands on your handlebar.
- If your fork and shock come equipped with compression damping knobs, make sure they are in the fully “open” position.
- Stand up on the pedals and bounce a few times. This will get the oil moving through your suspension and balances the air pressure in the shock. When bouncing, make sure you put a little pressure on the front of the bike, as if you were actually riding.
- Standing in your “neutral” position on the bike, have your friend reset the rubber O-rings on your fork and shock stanchions.
- Gently sit on the saddle and dismount your bike.
- Look at your stanchions.
With the ruler, measure the position of the O-ring on the stanchion. It should sit around 25% of the total length of the stanchion. If the O-ring is less than 25% of the way down, you have too much air in your shock or fork; use the shock pump to remove air. If the O-ring is more than 25% of the way down your stanchion, you have too little air in your shock or fork; use the shock pump to add air.
Adjust Rebound Damping
You’re halfway there. Now that your suspension feels just right with your given weight under compression, it needs to be adjusted properly so that it rebounds at the correct rate. These settings are just as important as the previous step. To properly adjust the rebound damping on your fork and shock, perform this procedure:
- Start by finding out how many “clicks” of rebound you have to work with. With most rear shocks and forks, you turn the rebound knob all the way to the left to minimize any damping force. Then, count the clicks as you turn the knob to the right. (Check the specific instructions with your particular shock or suspension fork.)
- With full body weight, push down on the saddle forcefully to compress the shock. Watch (and feel) how the shock rebounds from compression. Note that the shock rebounds very slowly.
- Next, turn the rebound damping knob left until it stops and compress the shock under full body weight. The shock now rebounds very quickly to its neutral position.
- Now turn the damping knob counterclockwise a few complete turns and re-perform your compression testing until the shock rebounds more slowly than with no damping.
A faster rebound damping is normally better for smaller bumps, while slower rebound feels better on big bumps. Make sure that the rebound feels right for your riding style and your specific terrain. Test your bike frequently to find out what setup is best for you. You can check the rebound by compressing and releasing the shock (by pressing down on the saddle) and the suspension fork (by pressing down on the handlebar. Make sure you are not holding onto the handlebars or saddle, but instead pressing with open hands to get an accurate feel. Your suspension should return to its natural position quickly, but not so quickly that it bounces your tire off the ground. Add or subtract clicks as needed.
The best way to determine your proper rebound is to really pay attention while riding. If you feel like your bike is trying to eject you when you land a jump or drop, or your ride feels really rough over technical terrain, you might want to slow down your rebound/ add more rebound damping. If you feel like your suspension is “packing up” (not returning to its natural position when riding over several bumps in quick succession), then you will want to speed up your rebound.
Use Compression Damping
How can you benefit most from compression damping? Consider that high-speed compression is more adequate for fast and rough hits. Low-speed compression damping is better for slower hits. In the end, it all comes down to what settings work best for you and your specific riding style and trail conditions.
Additionally, there are many different variations of compression damping found on both forks and shocks. You may find a high-speed, low-speed or lockout compression damping option—or any combination in between—on your specific product.
With ompression damping, you can control the speed of the compression. With more compression damping, your suspension will feel firmer, which means you won’t find yourself blasting through the travel with small impacts or when braking. However, with too much damping, the suspension cannot absorb large impacts--which can result in a harsh feeling.
The correct compression damping depends on personal preference and the terrain. Some riders like a plush, supple bike while others who ride rough trails with big hits prefer a firmer feel.
Suggested starting air pressure for setting sag.
The below overview gives you some insights in fork and shock pressures that you can use as a baseline. The measures differ based on the shock that your E-bike is equipped with. Again, these are just guidelines. In the end, the feeling that you prefer is most important.