Fern bikes have been causing a stir in the world of custom and boutique bikes for several years now. In collaboration with his girlfriend Kristin and her custom bag company GRAMM, Flo designed and built his idea of the perfect bikepacking bike. We had the great honor of testing the Fern Chuck Explorer exclusively for you!

For an overview of the test fleet head to the group test: The best bikepacking bike in review

Fern Chuck Explorer | 10.22 kg in size 56 | Manufacturer’s website

Fern – the bike brand from Berlin is a mixture of think tank and custom bicycle workshop. Together with his girlfriend Kristin and her company Gramm Tourpacking, trained product designer Flo Haeussler realises two-wheeled dreams of almost all shapes and sizes. The Chuck Explorer sent in by the duo was lovingly painted by Velociao and easily makes it into our all-time top five hottest test bikes! There’s no on-line configurator from any bike brand that will come close to getting you the same brilliant spec as found on this € 10,999 bike.

The groupset consists of a custom-painted Shimano DURA-ACE 7000 series crankset, an XT 12-speed derailleur from Shimano’s mountain bike range, TRP brakes and brake levers with Gevenalle shifters. Extraordinary looks meet excellent functionality. The OneUp Components dropper post can be operated using the left shifter and, together with the Tune Komm-Vor saddle and the modular cockpit, this is a build like no other. While this combination of components may raise a few questions, it also shows how versatile a bike can be when two artists/craftsmen/visionaries design and build it: lycra and asphalt today, singletrack tomorrow. All bags are bolted directly to the frameset, keeping everything super tidy and offering ingeniously integrated features such as the hydration bladder and its hose attached magnetically to the cockpit. With a weight of 10.22 kg (including front rack) in size 56, it certainly isn’t heavy for a steel bike.

Make the world the way you like it!
The modular cockpit allows you to adapt the bike however you want for your next adventure.
A fine line
Finding the right pressure is essential for the Continental tires. If it’s too low, they squirm. If it is too high, they lack damping.
Excellent combination
The unconventional groupset excels in both form and function.
The specially designed stem alone is worth drooling over.
Let there be light
The lights are powered by the hub dynamo. Their integration and position show that the minds behind this bike have a lot of practical bikepacking experience.

Fern Chuck Explorer

€ 10,999


Seatpost OneUp Components Dropper Post V2
Brakes TRP Hylex RS 160/160 mm
Drivetrain TRP, Shimano DURA-ACE/XT 38 (10–51)
Stem Fern Modular Custom 100 mm
Handlebar Fern Allygn 400 mm
Tires Continental Speed King RaceSport 56B

Technical Data

Size Custom
Weight 10.22 kg
Wheelsize 605B

Specific Features

available with front and rear racks
modular cockpit
custom bags by Gramm

Dual Frame Bag (€ 469) | Dropper Seat Bag (12 l, € 299)
Conical Top Tube Bag (1 l, € 107) | Gramm Fork Bag Pair (2 x 1 l, € 175)
Size Custom
Seat tube 516 mm
Top tube 550 mm
Head angle 72.5°
Seat angle 72.5°
BB Drop 75 mm
Chainstay 435 mm
Wheelbase 1,031 mm
Reach 387 mm
Stack 577 mm

If you see the Fern and still believe that a bike can’t have sex appeal, you’re a lost cause.

Helmet SCOTT Centric Plus | Glasses 100% Glendale | Jersey Vintage Market Stuttgart
Shorts GRAN FONDO x CUORE Custom | Shoes Dromarti Leather

When accelerating, the Berlin rocket prefers taking its time compared to the competition, but as you reach cruising speed, its afterburners ignite. With an almost stoic composure, excellent straight-line stability and high efficiency, the kilometers just fly by on the Fern. Endless gravel roads? Bring them on! Despite the 1x groupset, the size of the gear jumps is perfectly manageable, making it easy for roadie legs to find a suitable cadence. Shifting through the gears with the Gevenalle levers combines nostalgia with precision, offering quick and crisp gear changes. Things are a little less intuitive through corners. While the handling is good-natured and balanced, the high-volume Continental Speed King tires tend to squirm on the narrow Stan’s Crest MK3 rims when leaning the bike over. You’ll have to experiment with your tire pressures until you find the sweet spot.

Downhill and at high speeds, the bike instils you with confidence but to really push the bike to its limit in the corners, it takes a bit of time to get used to the feel of the tires. This clearly shows that a custom bike is just that, built to suit one specific person’s preferences. Due to the custom geometry, tubeset and components, it will never suit others as well as the person it’s built for. If you go custom and have special requests, you should know exactly what you want and how every little change affects the bike! In-depth research and talking shop with the builder are absolutely essential. The Fern gets top marks for comfort. Both the Continental tires and the wheels absorb impacts well, while the Columbus Life steel frameand the specially developed Allygn carbon fork offer excellent vibration damping. The balance between stiffness and compliance is spot on.

Tuning tips: wider rims to better support the tires when cornering | open a savings account and take notes while you dream about your bike


With its unique features and the sheer endless possibilities for customisation, the modular concept of the Fern Chuck Explorer is a perfect choice for experienced bike connoisseurs who know exactly what they want. Thanks to the bike’s composed handling and excellent long-distance comfort, there’s nothing to stop you from embarking on adventures lasting several weeks or more. The well thought-out and customizable Gramm Tourpacking bags are a natural extension of the bike’s modular concept and make it a great solution for everyone who only wants to own a single bike.


  • modular concept
  • technically and optically customised down to the last detail
  • long-distance comfort
  • groupset configuration


  • rims too narrow for the tires
  • custom geometry only fits the owner, making bike sharing difficult (but who wants to share a bike like this anyway?)

For more info head to fern-fahrraeder.de.

The test field

For an overview of the test fleet head to the group test: The best bikepacking bike in review

All bikes in test: Bombtrack Hook 2 (Click for review) | Canyon Grail AL 7.0 SL (Click for review) | Fern Chuck Explorer | Marin Headlands 2 (Click for review) | Mason Bokeh GRX (Click for review) | MERIDA SILEX+ 8000-E (Click for review) | RONDO BOGAN (Click for review) | ROSE BACKROAD AXS Mullet Build (Click for review) | Salsa Cutthroat GRX 600 (Click for review) | Specialized Diverge Comp Carbon (Click for review) | Specialized S-Works Epic HT AXS Custom (Click for review) | Trek Fuel EX 9.9 XTR Project One (Click for review)

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Words: Photos: Benjamin Topf, Robin Schmitt, Valentin Rühl