Test Bulls Grinder 4: The Cologne-based brand's aluminum gravel bike enters the new season with an improved frame. It also offers solid technology and a wide range of uses, from racing to commuting.
Anyone who waited until spring 2025 to buy a gravel bike will be rewarded by Bulls – with a new model of the Grinder. This aluminum gravel bike, which brings the frame geometry of the carbon Machete model to an attractive price point, has been given a frame adapted to current standards and is now fully up to date.
The Grinder hasn't been on the market for all that many years, but there are currently four versions available. Anyone heading to their nearest ZEG dealer looking for a gravel bike should take a close look, with the respective price tags providing a guide. The current base model is the Grinder 1, recognizable by the shift cables leading from the top into the top tube. This bike is equipped with traditional quick-release skewers on the front and rear wheels. The Grinder 2 – the shift cables lead into the top tube on both the left and right sides – already has a thru-axle on the fork.
Bulls Grinder 4: Thru axle now also at the rear
The Cologne-based manufacturer now also specs a thru-axle at the rear of the Bulls Grinder 4. Viewed from the drive side, the bike appears particularly tidy – the shift cable and brake line enter the down tube on the left. Another thing is striking: after the titanium Mache-Ti, this is the brand's second gravel bike with a UDH derailleur hanger. Even the carbon Machete bike doesn't yet feature this technology, which allows for the installation of SRAM's new direct mount rear derailleurs.
Will you ever need a part like this on your gravel bike? It's quite possible, because the high-quality frame of the Bulls Grinder 4 promises a long service life, which in turn makes a component upgrade possible. For now, however, the Shimano GRX-RX600 will get you through it very well. Okay, Bulls uses the 1×11 version, so they don't fit the brand-new twelve-speed version. However, the latter's advantage is marginal – the additional overdrive thanks to the 10-tooth sprocket is rarely needed, and the slightly lighter mountain gear (45 instead of 42 teeth) is only likely to be missed on extreme terrain. Our tip: ride the eleven-speed groupset for a few years and then upgrade to an electronic groupset – such as the Shimano GRX 1×12 Di2, which is expected to be launched this year.
Until then, you can enjoy the precise, reliable function of the mechanical-hydraulic group, which shifts as safely and smoothly as it brakes powerfully and precisely. And, of course, the Grinder itself, i.e., the aluminum frame with its many excellent features. These include a comfortable, not overly sporty riding position, which can, of course, be made considerably more aggressive by changing the handlebar stem – if you want, you can sit lower and stretched out in no time, thus having a bike that's almost ready for racing. And, especially with the short standard stem, the Bulls is exceptionally maneuverable, which makes for a lot of riding fun.
Many mounting options and large tire clearance
On the other hand, the Bulls Grinder 4, with its numerous mounting options, is perfectly suited for use as a long-distance gravel bike. Top tube and frame bags, as well as panniers on the fork, make it perfectly suited for bikepacking; a rear rack can also be attached, as can mudguards and even a kickstand. The 45 mm wide tires (50 mm wide tires will also fit) are ideal for both sports and travel. In competition, the large volume prevents tire punctures and improves dynamics; with luggage, it allows for a comfortable tire pressure despite the higher weight.
If you want, you can mount special battery-powered lights on the Bulls Grinder 4; a front light can also be attached if you install a dynamo-powered front wheel. However, if you're considering the latter, you should think about a few things before purchasing. The Cologne-based company has a sister model, the Bulls Daily Grinder 4, in its range, which is already equipped with everything you need for everyday use and travel, and costs just €100 more. And, of course, this bike is also based on the current frame with thru-axles and a UDH derailleur hanger.
