The Grin One Enduro bike is tested here for the first time in series and we can anticipate the eagerly awaited test report: Rarely have we ridden the very first production bike from a small, brand-new brand with a one-man show and been so convinced afterwards. Convinced that Grin have hit a nerve with their premiere bike and done a good job. Praise from the BIKE test editors sounds like the dream of every start-up manufacturer. In reality, however, the success story begins much earlier. What began as a private project during the coronavirus lockdown was soon to grow into a new player on the enduro market. The duel opponent is called Last Coal, here we have tested the opponent.
The Grin One in detail
- Area of application: Enduro
- Suspension travel: 170 / 165 mm
- Wheel size: 29"/27.5" (Mullet)
- Weight: 15.4 kg
- Maximum system weight: 120 kg
- Price: approx. 6000 euros (custom bodywork, frame price: 2450 euros)
- Warranty: 5 years
- Special features: Startup, tool mount, flip chip, various suspension travel options
From private fun to your own brand
Many mountain bike fans harbour the dream of one day developing their own bike. For Philipp Brunn, this dream became a reality in 2022, when the first prototype of the Grin One Enduro Bike rolled through the woods - and marked the start of an exciting project. Although the Odenwald native started with a blank sheet of paper, he was not entirely without previous experience. With over 20 years of professional experience in the automotive industry, Brunn brought with him technical expertise and a keen sense of design. As an enthusiastic bike mountaineer, Grin boss Brunn was disturbed by the trend towards increasingly unwieldy and heavy enduro bikes - so he quickly developed his own full-suspension model. After testing the first prototype, the revised concept was finalised in March 2023. At the end of July of the same year, several bikes from the second development stage were sent to a group of experienced test riders. The next prototype rolled onto the trails in mid-2024 and series production of the Grin One finally began in spring 2025.
Details that count
God put an uphill before a downhill - as a biker, Grin mastermind Philipp Brunn knows this very well. That's why a light weight despite the aluminium frame was important to him when developing the One. Grin specifies 3.35 kilos for a size M chassis. With lighter equipment, the test bike even undercuts its duel opponent from Last by 50 grams. According to Brunn, complete bike weights from just over 14 kilos are possible. For extra steep climbs, the frame is compatible with a tiny 26 mm chainring. Practical on tour: there is a tool mount under the top tube and a water bottle fits into the frame triangle. A flip chip allows you to choose between a high and a low setting for the geometry. In frame sizes L and XL, a 29er wheel also fits in the rear triangle. With size M, this is only possible with restrictions in the choice of tyres. With shocks of different lengths, you can choose between 150, 160 or - as in our case - 165 millimetres of suspension travel.
A threaded BSA bottom bracket and classic internally routed cables in the main frame as well as externally routed cables in the rear triangle improve the Grin One's ease of maintenance. Double bearing seals and full approval for Enduro, Downhill and Freeride inspire confidence in the durability of the Grin frames. Incidentally, these are manufactured entirely by the Taiwanese frame manufacturer Genio-Bikes, which also produces Raaw's frames. Grin framesets can be ordered directly via the homepage and assembled by the customer or by contacting a network of partner shops. The first order series comprises 150 frames and is not yet sold out. Grin does not currently offer complete bikes.
Equipment
- Suspension fork / shock: Rockshox ZEB Ultimate / Rockshox Vivid Air Ultimate
- Gear system: Sram GX Eagle 1 x 12
- Gear ratio: 30 x 10-52; 520%
- Brakes / disc size: Magura MT7 / 200/200 mm
- Telescopic post / stroke: OneUp Dropper / 210 mm
- Wheels: DT Swiss EX 1700
- Stem / handlebar: 77 Designz 35 mm / Pro Three 780 mm
- Tyres: Maxxis Assegai 3C MaxxGrip Exo+ 29 x 2.50 WT / Minion DHR II 3C MaxxTerra DD 27.5 x 2.40 WT
Data from the BIKE test lab
At BIKE, we go to unprecedented lengths to test bikes. We are the only trade magazine in the world to operate its own test laboratory. The data obtained supports our impressions from the practical test. When it comes to geometry data, we don't just rely on the manufacturer's specifications, but also use the laser measuring device ourselves.
- Complete weight: 15.39 kg (size 185, without pedals)
- Wheel weight: 5422 g (incl. tyres, tubes, tubeless rim tape, milk, valves, brake discs)
- Impeller inertia: 4396 kg x cm² (the lower the value, the better the acceleration)
How the new aluminium enduro bike from Grin rides on the trail
Most bike companies put years of development work into their series products. With Grin, the geometry fits right away. All four test riders liked the way the Pilot is integrated into the frame. A long but not extreme main frame meets a rear triangle that is slightly longer than on Last's duel opponent. Even if the geometry tables of both manufacturers are otherwise very similar, the chainstay length is a decisive difference. The length distribution between the front and rear of the Grin One is somewhat more balanced. This is worth its weight in gold for handling on fast downhills. Thanks to the short seat tube, which can actually be used thanks to a long Vario stroke, radical manoeuvres can be initiated in a controlled manner at any time. The Magura MT7 brakes grip the large brake discs from Galfer very sensitively and fully, but require more manual force than the radical Sram Maven on the load.
As the Grin maintains a balanced ratio of smoothness and manoeuvrability even at high speeds, we could well imagine entering this bike in an enduro race. The flat handlebar with a rise of just 15 millimetres puts a lot of pressure on the front and encourages experienced riders to pick up the pace. However, none of the riders really warmed to the cockpit of our test bike. "Too flat on steep sections, too stiff when things get really bumpy" was the verdict on the aluminium Pro handlebars with a fat 35 millimetre clamp. Speaking of stiffness: Although Grin does without a connecting strut between the solid seat stays, the stiffness of the rear triangle is high. In off-camber situations, the rear wheel can sometimes bounce. Light riders in particular should keep this in mind.
Counterstop before traction
Pushing through the terrain or pulling off a kicker is child's play on the Grin One. Also because the rear suspension neither sags nor bends too much. The Rockshox Vivid Air in the test setup is very defined in its travel and helps with the precise positioning of the bike. In direct comparison to the rear of the Last Coal, however, we missed sensitivity. Despite the large travel reserves, the Grin rear suspension is not a sensitive hoover, especially in the first travel range, but rather passes on some vibrations together with the potent stiffness. As a result, the Grin One is not quite as comfortable and unagitated as its test competitor. At the front, the powerful Rockshox ZEB Ultimate with 170 millimetres of travel leaves nothing to be desired. It guides the enduro bike through the terrain with a high sense of security thanks to the 63 degree steering angle.
The rear suspension of the Grin One comes into its own on the climbs. For a long-travel enduro bike, the rear end remains surprisingly stable even when pedalling and hardly wastes any valuable energy. There's no need to reach for the platform lever on tour. The overall weight also remains within the green range despite the robust equipment. However, the fact that the wheels are harder to get going than those on the load, despite the standard tyres, costs more energy on long rides. With a steep seat angle and flat control centre, there is a lot of pressure on the front when seated. Good for climbing steep ramps with low gears, but too extreme for shallow low mountain hills. There, the seating position feels squat and needs to be defused by a longer, higher cockpit set-up. Under load, the shifting precision of the classic Sram GX drivetrain and Garbaruk cassette can't keep up with the transmission drivetrain on the test antagonist. A negligible disadvantage for all non-racers.
BIKE review Grin One
Driving behaviour (65 %)
- Uphill riding behaviour (8 %): 3,00
- Uphill efficiency chassis (10 %): 1.50
- Play instinct (7 %): 2.50
- Downhill riding behaviour (20 %): 2.00
- Downhill chassis (20 %): 2.50
- Driving behaviour grade: 2.25
Laboratory (10 %)
- Weight (6 %): 3,50
- Inertia impellers (4 %): 3,50
- Lab grade: 3.50
Equipment (25 %)
- Equipment quality (5 %): 1.88
- Usability/added value (5 %): 3,00
- Transport volume bottle cage (5 %): 3,00
- Seatpost retractability (5 %): 0.50
- Quality/processing (5 %): 1.00
- Equipment grade: 1.88
BIKE overall grade: 2.28
The BIKE grade is made up of practical impressions from test riders and laboratory measurements. The grade is independent of price. Grading range: 0.5-5.5, analogue to the school grading system. The evaluation took place in the Enduro category.
BIKE conclusion
It's impressive what Grin has achieved with its first production bike! Riding position and riding fun are absolutely on point. The small startup could still do with some improvements in terms of sensitivity and optimising the stiffness of the rear triangle. If you fancy a sporty enduro bike that you won't find on every corner, you should definitely take a closer look at the Grin One. The newcomer only just missed out on the test victory. - Jan Timmermann, BIKE test editor
Pro
- drive-neutral rear triangle
- Balanced geo with successful rider integration
- Versatile bike with no-bullshit aluminium frame from German startup
Contra
- Rear suspension should be more sensitive
- suboptimal cockpit on the test bike
Jan Timmermann
Editor
