Set up e-bike suspension in three steps: set the sag so the fork or shock compresses 20-30 percent of its travel under your weight, adjust the preload or air pressure to match that sag, then tune the rebound so the suspension returns smoothly without pogoing. TST's full-suspension models use coil and air systems with adjustable rebound, and the rider-weight table below gives a starting point.

Setup guidance applies to TST full-suspension models including the R002, R7, and R9.

What Does Sag Mean and Why Does It Matter?

Sag is also the setting that most affects ride height and geometry, because a fork that sags correctly keeps the bike level under load, which changes steering and braking feel more than any other single adjustment.

Sag is how much the suspension compresses under your weight when you sit on the bike, and it is the foundation of every other setting. Too little sag (stiff suspension) means the wheel skips over bumps and transfers impacts to you; too much sag (soft suspension) means the suspension bottoms out and the bike sags in corners. The target is 20-30 percent of travel compressed at rest with you aboard.

Set sag before touching rebound or preload, because every other adjustment compensates for a sag that is already wrong.

How Do You Measure and Set Sag on a Full-Suspension E-Bike?

Measure sag by placing a zip tie on the fork stanchion or shock shaft, sitting on the bike in your normal riding position with your full gear, and dismounting to read how far the tie moved. Divide that distance by the total travel to get the sag percentage, then adjust preload or air pressure until the number lands in the 20-30 percent band.

On TST's models, the front fork and rear shock use adjustable preload; the GT63 adds an adjustable suspension system with heavier-duty tuning. Start with the manufacturer's suggested setting, then fine-tune with the sag measurement.

What Rider-Weight Starting Point Should You Use?

Rider weight	Suggested sag target	Typical fork air pressure (if adjustable)
130-170 lb	25-30% of travel	Lower third of range
170-220 lb	20-25% of travel	Middle of range
220-280 lb	20-25% of travel	Upper third of range
Over 280 lb	20% with firm rebound	Top of range, check payload

These are starting points, not rules: the final setting depends on terrain, load, and personal comfort.

Adjusting Preload and Air Pressure for Your Weight

Preload adjusts how much weight is needed to compress the spring, while air pressure (on air forks and shocks) adjusts the spring rate itself. Turn preload adjusters in small steps and re-measure sag each time; for air systems, add or remove a few psi and re-measure. The goal is the sag target with the adjusters in a sensible middle position, leaving room to tune in either direction.

For the R002 and R7, the front fork includes adjustable preload and a lockout, which locks the fork for pavement efficiency; leave the lockout off on rough roads and trails.

How Do You Tune Rebound Damping on the Fork and Shock?

Rebound controls how fast the suspension extends after compressing. Too fast, and the bike "pogoes" and feels bouncy; too slow, and the suspension packs down over successive bumps and rides harsh. Start with the rebound near the middle of its range, ride a bumpy section, and adjust in small clicks: slow the rebound if the front end feels springy, speed it up if the suspension feels like it is stacking up.

The correct rebound is the setting where the wheel stays in contact with the ground through a series of bumps, which you can feel as stability rather than bounce.

What Are the Model-Specific Notes for the GT63 and R002?

The GT63 uses a heavier-duty suspension setup with a nitrogen shock and hydraulic fork, tuned for off-road impacts, so its sag target leans toward the firmer end of the range and its rebound should be set slower for stability on jumps. The R002 and R7 use the adjustable full-suspension platform with front fork preload and lockout, best set for comfort on commutes and light trails.

For the R002, try the lockout on smooth pavement and off on rough roads; for the GT63, keep the rebound controlled enough that landings do not pogo, which is the difference between confidence and a bucking ride.

How Terrain Changes Your Suspension Settings

Set the baseline for your most common surface and fine-tune from there: commuters who ride pavement 90 percent of the time should run the fork firm with the lockout on for the smooth sections, while weekend trail riders should run the 25-30 percent sag and leave the lockout off. Riders who switch between both should treat the lockout as the daily control: on for the road commute, off for the trail, with the sag and rebound left at the trail setting so the bike is ready for the rougher ride.

Smooth pavement favors a firmer setup with the fork locked or near the top of the sag range, because suspension that moves too easily wastes pedal energy. Rough roads and trails favor the 25-30 percent sag and a controlled rebound, because the suspension's job is to absorb the terrain. Soft sand and snow favor a slightly softer setup for traction, within the sag range.

If you ride a mix, set the suspension for your worst terrain and use the lockout for the smooth sections, rather than chasing a perfect single setting.

When Should You Have Suspension Serviced?

Set the service interval in the calendar when the bike is new, because suspension wear is invisible until it is not: a fork that feels slightly harsher each month is a fork that needs service, not a fork that "broke in." The signs to watch are oil residue on the stanchions, a fork that sticks at a point in its travel, suspension that no longer holds the sag setting, and knocking or creaking from the shock over bumps. Catching these at the annual service is a $100-150 job; ignoring them can turn into a $300-500 rebuild.

For owners who ride mostly pavement, the annual interval is plenty, and the lockout reduces wear by keeping the fork rigid on smooth roads; for off-road riders, the 200-300 hour interval is the safer guide. Keep the service receipts with the bike's log, because a documented service history also strengthens warranty claims if a component fails later.

Service the fork and shock annually or every 200-300 hours of off-road riding, whichever comes first: a basic service cleans and re-lubricates the internals, and a full service replaces seals and oil. Signs that service is due include oil on the stanchions, a fork that sticks or tops out, lost sag adjustment, and new knocking noises from the shock.

Suspension is the most neglected component on e-bikes, and a $100 annual service keeps a $500+ suspension system working like new.

TST EBike Expert Views

"Suspension setup is a three-step process and the order matters: sag first, then preload or air pressure, then rebound. We see riders trying to fix a harsh ride with rebound clicks when the real problem is sag set too low, or chasing bottom-out when the preload was never matched to their weight. Measure the sag with a zip tie, set the 20-30 percent target, and tune from there. On the R002 and R7, the lockout is your friend on pavement; on the GT63, keep the rebound controlled and the landings stay predictable."

— TST EBike Engineering Team (this article is written by TST EBike's editorial team, which works for the manufacturer)

Conclusion: Sag, Preload, Then Rebound

E-bike suspension setup is three ordered steps: set the sag to 20-30 percent of travel, match the preload or air pressure to that sag, then tune the rebound for the terrain. Measure with a zip tie, adjust in small steps, and service the system annually, and the ride stays comfortable for years.

Suspension Setup Checklist

Measure sag with a zip tie and your normal riding weight.
Set sag to 20-30 percent of travel.
Adjust preload or air pressure in small steps, re-measuring each time.
Tune rebound for the terrain; keep the wheel planted through bumps.
Use the lockout on smooth pavement and off on rough roads.
Book an annual service or every 200-300 off-road hours.

See the TST front fork shock absorber page for replacement parts, and check the R002 product page for the full-suspension spec.

Related reading: how to adjust e-bike brakes

FAQs

What sag should my e-bike suspension have?

20-30 percent of travel under your normal riding weight; measure with a zip tie on the stanchion or shaft.

How do I stop my suspension from bottoming out?

Increase preload or air pressure until the sag lands in the 20-30 percent band, then recheck on the terrain you ride.

What does rebound damping do?

It controls how fast the suspension extends after compression; too fast causes bounce, too slow causes harsh, stacking rides.

How often should I service e-bike suspension?

Annually or every 200-300 hours of off-road riding; signs include oil on stanchions, sticking forks, and lost sag adjustment.

How Do You Set Up E-Bike Suspension for Comfort?