YT Jeffsy Primus: suspension setup & specs
The YT Jeffsy Primus is a trail bike with 130–140 mm of fork travel and 130–140 mm at the rear. Below you will find all 2 current builds with fork, shock and shock size, plus SAG values in millimetres and a tyre pressure table.
Calculate the setup for your YT Jeffsy Primus →
All builds
Fork, shock, shock size (eye-to-eye length × stroke) and rear travel, weight and price according to the manufacturer. Wheel size: 24" / 26".
| Build | Fork | Shock | Shock size | Rear travel | Weight | RRP | Calculator |
|---|---|---|---|---|---|---|---|
| 24 | Manitou Machete Junit (130 mm) | Manitou Mara Inline | 190x40 | 130 mm | – | – | Setup → |
| 26 | RockShox Reba (140 mm) | RockShox Deluxe Select | 190x45 | 140 mm | – | – | Setup → |
How it compares
On travel, the YT Jeffsy Primus is right where the “trail bike” category usually is: 130–140 mm up front against a median of 140 mm from 44 bikes. On travel, it slots in between the YT Dirtlove and the YT Izzo in the YT range.
For suspension, YT combines components from Manitou and RockShox. In total, 2 different forks are used, from the Manitou Machete Junit to the RockShox Reba. Depending on build or size, the wheels are 24" / 26".
Setup notes for this spec
- Fork (RockShox Reba): air goes in through the valve on top of the left leg. After every change, compress the fork firmly a few times before measuring SAG.
- Rebound: on RockShox suspension the rebound adjuster is red. Always count clicks from fully closed (clockwise to the stop) so you can return to any setting.
- Air shock (Manitou Mara Inline): measure SAG in your riding position, ideally with a helper holding the bike. Cycle the shock a few times after every pressure change.
Target SAG for the YT Jeffsy Primus
SAG is the share of travel your weight already uses in the riding position. The table gives it straight in millimetres – read the O-ring on the stanchion and on the shock shaft and adjust the air pressure until it matches. Any figures from YT take priority.
130 mm fork, 40.0 mm shock stroke (24)
| Riding style | Fork SAG | Shock SAG |
|---|---|---|
| XC / touring | 17 % = 22 mm | 24 % = 9.6 mm on the shock shaft |
| Trail | 20 % = 26 mm | 28 % = 11.2 mm on the shock shaft |
| Enduro / rough | 22 % = 29 mm | 30 % = 12.0 mm on the shock shaft |
| Bike park | 20 % = 26 mm | 27 % = 10.8 mm on the shock shaft |
140 mm fork, 45.0 mm shock stroke (26)
| Riding style | Fork SAG | Shock SAG |
|---|---|---|
| XC / touring | 17 % = 24 mm | 24 % = 10.8 mm on the shock shaft |
| Trail | 20 % = 28 mm | 28 % = 12.6 mm on the shock shaft |
| Enduro / rough | 22 % = 31 mm | 30 % = 13.5 mm on the shock shaft |
| Bike park | 20 % = 28 mm | 27 % = 12.2 mm on the shock shaft |
How to measure SAG is explained in our guide SAG setup.
Tyre pressure starting values
For 2.40″ wide tyres, tubeless with a trail casing. With an inner tube about 0.2 bar (2.9 psi) more, with an insert about 0.1 bar (1.5 psi) less.
| Ready-to-ride weight | Front | Rear |
|---|---|---|
| 60 kg | 1.43 bar (21 psi) | 1.63 bar (24 psi) |
| 70 kg | 1.55 bar (22 psi) | 1.75 bar (25 psi) |
| 80 kg | 1.67 bar (24 psi) | 1.87 bar (27 psi) |
| 90 kg | 1.79 bar (26 psi) | 1.99 bar (29 psi) |
| 100 kg | 1.91 bar (28 psi) | 2.11 bar (31 psi) |
| 110 kg | 2.03 bar (29 psi) | 2.23 bar (32 psi) |
| 120 kg | 2.15 bar (31 psi) | 2.35 bar (34 psi) |
Air pressure in the fork and shock
The sticker on the fork (or on the shock) and the manufacturers’ setup charts give you a first pressure. Our calculator is more precise and suggests rebound too – always check the result via SAG.