Test: With its 1x11 gearing and aggressively profiled tires, the Bulls Grinder 4 is aimed at sporty riders who will find the compact, agile bike a lot of fun to ride.
The Grinder has been on the market for six years and is quite popular due to its versatility. As a trail grinder with a dropper post and extra-wide tires, it appeals to off-roaders, and as a fully-equipped daily grinder, it's well-suited for commuting and luggage tours. And of course there is the bike as a "real" Graveller, with the Grinder 4 being the most expensive version at 2.049 euros. Like its cheaper siblings, it is based on an aluminum frame with a carbon fork that appeals with its harmonious shapes: the main tubes are round, with the top tube being ovalized; The gear cable and brake line run in the down tube, but the hydraulic line is routed on the outside of the fork. You can mount two bottle cages - with a magnetic Fidlock bottle cage already attached to the down tube - plus mudguards and a rear luggage rack.
Compact and lively
Of course, the already mentioned versatility requires a suitable geometry. Sitting on the Bulls is quite compact and rather upright, which is also helped by the short stem. This contributes to a very manageable, agile steering behavior, which makes the Bulls extremely sporty to drive - when driving slowly it is a bit nervous and has to be directed with a steady hand. The perceived high rigidity ensures brisk acceleration. Bulls mounts a special carbon seat post with an oval cross-section, which has to be pushed into the seat tube together with a spacer and is intended to dampen vibrations. Of course, some conventionally round carbon posts flex significantly more than the Duroflex model from Bulls. Also typical of the brand are the slots on the seat clamp and stem, which are equipped with reflectors on the test bike. They take special battery lights, which then hold firmly and twist-free on the wheel.
Snappy brakes, precise shifting
The Grinder 4 officially comes with a complete Shimano GRX-RX810, with the 600 shifters mounted on the test bike, which are a little more comfortable to hold thanks to smoother rubber grips. With 1×11 gears, the Grinder 4 has a sporty setup, with a 40 chainring and 11 to 42 teeth wide enough at the rear. The snappy brakes and precise shifting of the group are convincing across the board - no wonder that the GRX sets the standard for gravel bikes. In addition, there is a solid 32-spoke wheel set that weighs a good four kilos ready to ride and, like the snappy Schwalbe tires, can be ridden without inner tubes - that should save almost 200 grams. But in view of the Bull's pleasant driving characteristics, you don't have to look at the gram.
| Frame | Aluminium |
| Fork | Carbon |
| Wheels | Bulls |
| Tires | Schwalbe G-One Ultrabite TLE |
| Derailleur | Shimano GRX RX810 |
| Shifter | Shimano GRX RX810 |
| Crank | Shimano GRX RX810 |
| Front derailleur | |
| Brake | Shimano GRX810 |
| Seatpost | Bull's Duroflex Carbon |
| Saddle | Bulls |
| Stem | Bulls MTB SL CCS |
| Handlebar | Bull's Gravel Bar |
Of course, we would have liked a little more care with the test bike's looks - the green tones of the frame, tires and fork don't really go together (although our grass-green pedals don't make it any better). And with this bike, too, one should point out the model one step below, the Grinder 3. It is also equipped with GRX 1×1, the frame looks identical except for the quick-release axle at the rear – but it costs a whopping 500 euros less. Perhaps the more interesting offer, especially for beginners…
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