Bulls Sonic SX: suspension setup & specs
The Bulls Sonic SX is an e-hardtail with 120 mm of fork travel. It is powered by Bosch Performance Line SX (Smart System) 25/55 Nm. Here you will find all 2 current builds with fork, plus matching SAG and tyre pressure starting values.
Calculate the setup for your Bulls Sonic SX →
All builds
Fork, motor, weight and price according to the manufacturer. Wheel size: 29.
| Build | Fork | Motor | Weight | RRP | Calculator |
|---|---|---|---|---|---|
| Dakar | RockShox Psylo Gold Air (120 mm) | Bosch Performance Line SX (Smart System) 25/55 Nm | 20.5 kg | €5,799 | Setup → |
| 2 | RockShox SID (120 mm) | Bosch Performance Line SX (Smart System) 25/55 Nm | 17.7 kg | €6,399 | Setup → |
How it compares
120 mm at the fork almost exactly matches the 120 mm median of the 27 bikes in the “e-hardtail” category in our database. Among Bulls’s e-mountain bikes, the Bulls Sonic SX has the shortest fork travel. Bulls builds the frame from carbon.
The lightest build, 2, weighs 17.7 kg according to Bulls – about 6.7 kg less than the category median (24.4 kg across 11 bikes with a stated weight). There are 2.8 kg between the lightest and the heaviest build. The Bulls Sonic SX is not a budget bike: even the Dakar build costs €5,799, while the category median is €3,150. For the 2 build, Bulls asks €6,399. Up front, all builds get a RockShox fork. The fork line-up ranges from the RockShox Psylo Gold Air to the RockShox SID. It is powered by Bosch Performance Line SX (Smart System) 25/55 Nm. Bulls specifies a maximum system weight of 130 kg. Subtracting roughly 21 kg for the bike leaves about 109 kg for rider, clothing, backpack and luggage.
Setup notes for this spec
- Fork (RockShox Psylo Gold Air): 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.
- e-MTB: because of the extra weight, start with slightly more tyre pressure – the surcharge is already built into the table below.
- Hardtail: without rear suspension, rear tyre pressure largely decides comfort and traction – it is worth testing in 0.1 bar (1.5 psi) steps.
Target SAG for the Bulls Sonic SX
Instead of percentages, this table gives SAG directly in millimetres, measurable with the O-ring on the stanchion. Change the pressure step by step until you reach the value; if Bulls gives its own target SAG, use that.
120 mm fork (all builds)
| Riding style | Fork SAG |
|---|---|
| XC / touring | 17 % = 20 mm |
| Trail | 20 % = 24 mm |
| Enduro / rough | 22 % = 26 mm |
| Bike park | 20 % = 24 mm |
How to measure SAG is explained in our guide SAG setup.
Tyre pressure starting values
Basis: 2.40″ tyre width, tubeless, trail casing, including the e-MTB surcharge. 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. Stock tyres: SCHWALBE G-One Allround; SCHWALBE NOBBY NIC Perf, Folding.
| Ready-to-ride weight | Front | Rear |
|---|---|---|
| 60 kg | 1.48 bar (21 psi) | 1.68 bar (24 psi) |
| 70 kg | 1.60 bar (23 psi) | 1.80 bar (26 psi) |
| 80 kg | 1.72 bar (25 psi) | 1.92 bar (28 psi) |
| 90 kg | 1.84 bar (27 psi) | 2.04 bar (30 psi) |
| 100 kg | 1.96 bar (28 psi) | 2.16 bar (31 psi) |
| 110 kg | 2.08 bar (30 psi) | 2.28 bar (33 psi) |
| 120 kg | 2.20 bar (32 psi) | 2.40 bar (35 psi) |
Air pressure in the fork
You will find a suitable starting pressure on the sticker on the fork stanchion 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.