YT Jeffsy: suspension setup & specs
The YT Jeffsy is an all-mountain bike with 150 mm of fork travel and 145 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 →
All builds
Fork, shock, shock size (eye-to-eye length × stroke) and rear travel, weight and price according to the manufacturer. Wheel size: 29".
| Build | Fork | Shock | Shock size | Rear travel | Weight | RRP | Calculator |
|---|---|---|---|---|---|---|---|
| CORE 1 | Marzocchi Bomber Z1 (150 mm) | Marzocchi Bomber Air | 210x55 | – | – | – | Setup → |
| CORE 4 | FOX 36 Float Factory (150 mm) | FOX Float X Factory | 210x55 | 145 mm | – | – | Setup → |
How it compares
With 150 mm of fork travel, the YT Jeffsy is on the shorter side; the median of the 15 comparable bikes in the “all-mountain bike” category is 160 mm. The rear offers 145 mm, 5 mm less than the front. Within YT’s mountain bikes, it sits between the YT Izzo and the YT Capra on travel.
Depending on the build, fork and shock come from FOX and Marzocchi. In total, 2 different forks are used, from the Marzocchi Bomber Z1 to the FOX 36 Float Factory.
Setup notes for this spec
- Air fork (Marzocchi Bomber Z1): the air valve is on top of the left leg under a cap. Change pressure in small steps (about 5 psi (0.34 bar)) and cycle the fork a few times afterwards so the air chambers can equalise.
- Rebound: turn the red FOX and Marzocchi adjuster fully closed first and count clicks from there – that way you can note settings and restore them later.
- Shock (FOX Float X Factory): get on the bike in your normal riding position, step off carefully and read the O-ring. Always cycle the shock a few times after pumping.
Target SAG for the YT Jeffsy
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.
150 mm fork, 55.0 mm shock stroke (all builds)
| Riding style | Fork SAG | Shock SAG |
|---|---|---|
| XC / touring | 17 % = 26 mm | 24 % = 13.2 mm on the shock shaft |
| Trail | 20 % = 30 mm | 28 % = 15.4 mm on the shock shaft |
| Enduro / rough | 22 % = 33 mm | 30 % = 16.5 mm on the shock shaft |
| Bike park | 20 % = 30 mm | 27 % = 14.9 mm on the shock shaft |
How to measure SAG is explained in our guide SAG setup.
Tyre pressure starting values
Basis: 2.40″ tyre width, tubeless, trail casing. If you run tubes, add about 0.2 bar (2.9 psi); with an insert, about 0.1 bar (1.5 psi) less is enough.
| 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
You will find a suitable starting pressure on the sticker on the fork stanchion (or on the shock) or in the suspension manufacturers’ setup charts. Our calculator gives you a starting value including rebound for your weight and riding style. What matters afterwards is the measured SAG from the table above.