Gravel bikes under 2000 euros on test: The Bulls Grinder 4 - for the big tour

>> Here is an overview of all the bikes tested

More than 10,000 specialist bicycle dealers in Germany and neighbouring countries make up the Cologne-based Zweirad-Einkaufs-Genossenschaft (ZEG), which also stocks its own brands for its dealers, including the sporty Bulls brand. For last year's Gravel Special, we were already able to take a close look at the carbon bike called Machete as a novelty; in this test field, the Cologne-based company is now sending the more affordable aluminium counterpart Grinder with the highest quality equipment. The geometry of the Machete remains unchanged, which means, among other things, that you sit very upright on the bike. Due to the short stem and a seatpost without offset, the distance between the saddle and handlebars is relatively small; on the size M test bike, the 1.80 metre tall testers felt a little cramped. The fact that the handlebars are almost three centimetres higher on the next size L should be borne in mind, especially by prospective buyers who are unable to test ride the bike before purchasing it. The width of the handlebars, with only a slight difference in height between the upper and lower handlebars, also emphasises the idea of a rather comfortable tourer.

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Bulls Grinder 4: Mileage collector instead of manoeuvrability

This is matched by the handling, which is characterised by stoic straight-line stability. With a total weight of a good eleven kilograms and comparatively heavy wheels, the bike doesn't seem very lively overall, but it is stable even on rough slopes and forgives many a small riding mistake. In the TOUR test lab, the Grinder reveals an extremely stiff frame set; high payloads should therefore have little effect on it. A point of criticism and at the same time a decisive damper on the overall score is - in addition to the high weight - the below-average suspension comfort, especially at the front: the massive carbon fork, the stubby stem and the unyielding aluminium handlebars mean that there is hardly any suspension at all. This can only be compensated for by the tyre pressure, at least the tyres have a good grip of 45 mm, although they are somewhat narrower on the rims.

Compromise on the gearbox

The robust "grinder" (the German meaning of "grinder") is clearly designed for touring; a number of eyelets for attaching bottle cages, pannier racks and mudguards invite you to trim the bike for an expedition course. The four threaded eyelets under the top tube, to which a frame bag (available as an accessory) can be attached, are unusual. The bike also comes with plug-in light mounts, into which only reflectors are clipped at the time of purchase; they don't look particularly stable. We would recommend higher-quality battery lights or converting to dynamo lights, as cable ducts are provided in the fork and frame. The Shimano GRX gearbox with one chainring and eleven sprockets requires compromises on the test bike. The only slight gear reduction in first gear could be too tight for less trained cyclists when there is a lot of luggage on the bike on steep climbs. At the other end of the gear ratio spectrum, the 40 mm chainring does not allow for high speeds on the road; you have to let the Grinder roll from 45 km/h at the latest.

The jumps between the gears are also large, especially in the middle range. Unfortunately, Bulls does not offer a qualitatively comparable version of the bike with a 2x crankset. If you want to ride faster and mainly ride on paved roads or asphalt, you might like the 2x10 road bike gearbox (Shimano Tiagra) and fast 38-millimetre tyres: It costs 100 euros more than our test model.

Eleven variants of the Bulls Grinder

The cheaper versions of the off-road grinder - the entry-level model starts at 1299 euros - are partly equipped with a double chainring, but then only offer 40-millimetre tyres and only mechanically operated disc brakes, which we would no longer recommend for use on a touring bike. Commuters might be interested in one of the three fully equipped models with mudguards, pannier rack and dynamo light; the top version for € 1999 has already convinced us in the test. The portfolio is rounded off by two women's models based on a low step-through frame. The Machete with a lighter carbon frame starts at 2799 euros.

Bulls Grinder 4: Info & test grade

• Price: 1899 Euro
• Weight of complete wheel: 11.2 kilos
• Frame sizes: S, M, L, XL (test size greased)
• TOUR grade: 2,8

Geometry

• Seat/top/head tube: 432/565/161 millimetres
• Stack/Reach/STR: 611/383 millimetres/1.60
• Stack+/Reach+/STR+: 664/554 millimetres/1.20
• Wheelbase/caster: 1000/64 millimetres

Equipment

• Drive/gear shift: Shimano GRX 600/812 (1x11; 40, 11-42 t.) | Grade: 3.0
• Brakes: Shimano GRX 400 (160/160 mm) | Grade: 2.0
• Tyres: Schwalbe G-One Bite TLE 45 mm (eff.: 42 mm) | Grade: 1.0
• Impellers: Ryde Road 21/Formula
• Impeller weights: 1998/2681 gram (f./h.)

Measured values

• Weight of complete wheel: 11,180 grammes | Grade: 5.0
• Driving stability: 10.5 N/mm | Grade: 1.0
• Rear comfort: 178 N/mm | Grade: 2.7
• Comfort front: 142 N/mm | Grade: 4.3
• Ride/ bottom bracket stiffness: 94 N/mm | Grade: 1.0

Advantages and disadvantages of the Bulls Grinder 4

• Plus: Very robust frame, many mounting options for accessories
• Minus: only four roughly graded sizes, relatively heavy and hard

All 13 bikes in the comparison test

• Bulls Grinder 4
• Canyon Grizzl 7
• Carver Gravel 220 1by
• Cube Nuroad C:62 One >> available here
• Focus Atlas 6.7 >> available here
• Giant Revolt 0 >> available here
• Megamo Jakar 20 >> available here
• Merida Silex 400 >> available here
• Radon Regard AL 10.0
• Ridley Kanzo Adventure Alu
• Rose Backroad AL GRX RX400 >> available here
• Scott Speedster Gravel 10 >> available here
• Stevens Prestige >> available here

How TOUR tests

Weight (25 per cent of the overall grade): The weighed complete wheel weight in the standardised test wheel size 56-57 centimetres counts for the evaluation. We also show the wheel weights for orientation. The grading scale is set in such a way that a grade of 1.0 is technically achievable: we award the best grade for weights under 7.5 kilograms.

Rear comfort (20 per cent): A measure of compliance under road shocks, measured in the TOUR laboratory. A suspension travel is measured when the seatpost is loaded. The measured value correlates very well with the riding impressions and the feeling of comfort. Good marks also mean decent riding dynamics, which have a positive effect on speed on poor roads and off-road.

Comfort Front (10 per cent): The deformation of the handlebars under load is determined in the same way as for the rear. A good score means a lot of suspension comfort, which takes the strain off your hands on long rides. However, strong sprinters who want a lot of stiffness should look for stiff handlebars.

Front stiffness (10 per cent): Important parameter for steering precision and confidence in the bike at high speeds, determined in the TOUR laboratory. The overall stiffness is determined on the fully assembled frame set, i.e. including the fork. The stiffness values are capped. The aim is not an infinitely stiff frame, but one that is sufficiently stable to ride.

Bottom bracket stiffness (10 per cent): Reveals how much the frame yields under hard pedalling, for example when sprinting. This measurement also takes place in the TOUR laboratory, with realistic clamping, in which the frame can deform as it would when riding.

circuit (5 per cent): The shifting characteristics are determined in the driving test. It is not the price or the quality impression of individual components that is assessed, but exclusively the function of the entire gearbox. The gear range, but also, for example, the cable routing, the quality of the cables and the mounted chain play a role.

Brakes (5 per cent): As with shifting, the test on the road also counts here, and the experience from our countless tests of brakes is also incorporated into the assessment. It is not the component itself that is assessed, but the function of the interaction between the brake body, pads and discs: How well can the brakes be modulated? How durable are the brakes, how do they react in hot or wet conditions, how long are the braking distances?

tyres (5 percent): Rolling resistance and grip are evaluated - as far as known from one of our independent tyre tests or based on driving impressions. The tyre width has no influence on the rating, as this is more a question of personal preference.

Lacquer (5 per cent): The TOUR paint test simulates stone chipping and allows a statement to be made about the durability of the protective top coat. A chisel simulates stone chipping or chain impact. Starting at a height of ten centimetres, the height is increased by ten centimetres until the paint gives way or the maximum drop height of 50 centimetres is reached.

Maintenance/adjustment (5 per cent): The test assesses how easy a bike is to maintain and adjust. Marks are deducted, for example, for special tools required, particularly complex detailed solutions, manufacturer-specific components or maintenance work that can only be carried out in specialised workshops. The overall score is calculated arithmetically from the differently weighted individual scores (percentages in brackets). It primarily expresses the sporting qualities of the bike.

The overall score is calculated arithmetically from the individual scores weighted differently (percentages in brackets). It primarily expresses the sporting qualities of the bike.

>> We have compiled all the information about our test here