The G1 GPI- All Gravity Performance, Low Maintenance

The G1 GPI – it shares the same DNA as the G1 which is synonymous for its ruggedness, adaptability and performance driven roots. Our goal is to make bikes that last longer and are easier to live with and the G1 GPI adds its own advances in durability, long-term reliability, and minimal maintenance. At the heart of the frame is a PINION C1.12i 12-speed electronically operated gearbox paired with a GATES Carbon Drive belt, ensuring smooth and efficient power transmission to the rear wheel.

The G1 GPI is best described as a Superenduro-an adaptive gravity platform designed for a wide range of riding styles and conditions. Whether on the enduro race track, downhill course, bike park jumplines, or long alpine adventures, the G1 GPI can be adapted to give you the perfect ride on your perfect trail.

Navigate down this page to find : Geometron G1 GPI product overview, Size guide & Geometry chart, Bundle Pricing & How to Buy

Built to last

LESS MAINTENANCE = LOWER COSTS + MORE RIDE TIME

The integration of a PINION gearbox offers significant advantages over traditional derailleur-based systems. With an overall gear range of 600% and consistent 17.7% gear steps, the PINION C1.12i outperforms conventional 12-speed derailleur systems, which typically offer only 500–520% range. All moving components are sealed inside a robust, protective housing, shielding them from dirt, debris, and impact damage. The PINION C-line gearbox service interval is a whopping 10000Km. Say goodbye to bent derailleur hangers and constant adjustments, instead, enjoy precise, instant gear shifts, even under load or while stationary. Alongside these attributes the gearbox brings other performance improvements. A drivetrain unit integrated in the center of the mainframe means an optimised weight balance of the bike. The gearbox enables us to have a real impact on changing the sprung to unsprung mass ratio on a bicycle. The lighter the unsprung mass, the more reactive the suspension system and the easier it is for the rear wheel to follow the terrain. The unsprung mass consists of the components that aren’t supported by the suspension e.g. wheels, derailleur, chain and seat stays. We have been great proponents of increasing the sprung to unsprung weight ratio of our bikes, you only need to strap weights to the frame of your current bike or simply ride an Ebike to experience the effect a change in that ratio has to the ride and suspension feel. The component (chain or belt) that transfers the power of the rider to the rear wheel also transmits a force that has an impact on the suspension system – pedaling induced forces also known as Anti Squat. The vector of the force depends heavily on the chosen gear on a standard cassette. That makes it difficult to design a suspension system that behaves similar in all the 12 gears a modern cassette offers. The G1 GPI has a constant chainline between the front and rear sprockets which means the suspension system can be designed in a way to maximise the positive effects the pedaling forces have on the performance and the pedaling efficiency of the bike.

Mutators – The G1’s strong suit: Adaptation and Customization

Empowering riders to fine-tune every aspect of their ride experience

Riders can choose between 162mm or 175mm of rear travel, adjustable via two mounting positions for the shock on the rocker link. The frame accommodates suspension forks from 150mm travel for an agile and responsive trail bike setup, all the way up to a 200mm dual crown DH fork. The GEOMETRON factory setup recommendation is based on a 170mm travel fork in order to cover a wide variety of terrain and riding styles. 

At the heart of the G1’s design philosophy lies its adjustability, empowering riders to fine-tune every aspect of their ride experience. Whether smashing technical descents or powering through demanding climbs, the G1 can be tailored to suit individual riding styles, strengths, and the unique terrain encountered. The key to the G1’s adaptability are the modular frame adjusters, aptly named Mutators located at the chain stay and seat stay, independently isolating geometry changes without compromising other ride characteristics. They allow for incremental changes to the head angle, bottom bracket height, chainstay length and most importantly to change the wheel size. The system allows the bike to be configured as a 29er, 27.5er, or mixed-wheel setup. This system also enables riders to optimize the weight distribution and handling characteristics according to their preferences and the demands of the trails they choose to ride. We have curated a useful tool called the Mutation chart within our tech sheet which shows the geometry of each frame size and the range of adjustment available, and what incremental changes can be made so that each rider can select their preferred configuration. Additionally, we offer comprehensive documentation and personalized advice, helping non-experts understand the core principles of geometry adjustment and setup optimization so they can make the most of their ride.

If you thrive on experimenting and making adjustments, this frame allows you to create your own ultimate test mule-all in one package. On the other hand, if you’d rather focus purely on having fun and disconnecting, the G1 can be as simple and intuitive as you need it to be. We’ve carefully crafted a base geometry that delivers outstanding handling, boosting your confidence and control so you can simply get out and ride. The G1’s base geometry is designed to suit the needs of the vast majority of riders. 

Fair warning: you might find yourself riding faster, having more fun, and even leaving your buddies behind on your local trails.

The Smart.Shift system is equipped with a BLE (Bluetooth Low Energy) interface, enabling connection to the new PINION Smart.Shift app. Through the app, riders can customize shifting performance and adjust shift button functions. Features such as Start.Select (which presets a gear for starting off) and Pre.Select (which enables cadence-dependent shifting while coasting) can be optionally activated and configured. The app also provides real-time information on battery status, software updates, and access to a built-in service tool. The Smart.Shift system is powered by a small battery pack concealed within the frames downtube. The battery pack provides well over 20,000 shifting operations, which corresponds to about 100 pure operating hours according to PINION and the battery and wiring is waterproof according to IPX7. In under 3 hours, the battery will fully charge via a dedicated cable interface.

Horst Link, Anti-Squat and Anti-Rise

The rear triangle of the G1 is designed around the Horst-Link concept, offering constant progression of 30% throughout the entire linkage movement. This design provides a sensitive response to small bumps, ensuring maximum grip and traction, while also offering ample usable travel with ideal support in the mid-stroke and a solid reserve for hard hits and landings.

Unlike derailleur systems, where the anti-squat value fluctuates depending on the selected gear, the G1 GPI maintains a constant anti-squat value of 115% calculated at 30% sag. Anti-squat refers to the force generated by the drive belt during pedaling. This causes the rear end to either squat or lift, depending on the suspension layout. A well-engineered linkage design can leverage this behavior to counteract chassis movement caused by pedaling forces, improving efficiency and control. This feature enables the G1 to climb efficiently and accelerate without losing momentum, even as a long-travel bike.

The anti-rise value, which counteracts the movement the chassis experiences when the rear brake is applied is 70%, calculated at 30% sag. This ensures that the suspension remains active under braking, providing better traction and stability when descending or during hard braking.

Sizing guide

There is no right or wrong size for you, pick the size that feels the most comfortable and confidence inspiring for your riding style.

A few years back we used Long / Longer / Longest / Extra Longest to describe the sizing of our models (our Small sized frames had the same reach measurement as most manufacturers XL sized frames) but the mainstream manufacturers are slowly evolving, growing their bikes millimetre by millimetre and degree by degree one model year at a time (remember when every company was using Longer, Lower and Slacker in their marketing campaigns)   The G1 geometry is not based around gender but rather a selection of sizing from Small to XXL that is ideal for almost any sized person, the G1 is very configurable, we can adjust for a huge variety of trail styles, riding styles, rider injuries and bike setup preferences. If you don’t “fit” into this category then we offer bespoke TAILOR MADE frames that are customer specific, you have free reign over all dimensions. When looking for a starting point to pick a size we recommend using the “Reach” measurement as it dictates how the bike actually fits you. It governs if a bike is too cramped or too stretched out for you. It’s a good indicator of how roomy the bike will feel when you are in your attack position standing on the pedals riding down the trail! So what G1 frame size should you ride?   We would strongly urge you to visit our HQ and try out our demo bikes! We understand this is not always an option for our overseas customers so here’s an easy-to-digest table with ‘rider height’ in one column and ‘frame size’ in the other….   But before looking at the table please ask yourself these questions when determining frame size:   1, Do you have a good range of movement? i.e. no injuries that hinder / restrict body movement? 2, What’s your cycling background, did you grow up on BMX and 4x or make the transition from road cycling? 3, What style of trail are you riding? Steep or undulating, fast and open or tight and technical, natural or bike park. 4, Are you a wheels on the ground rider or do you send it? 5, Are you “active” on the bike picking out the flow lines or do you tend to straight-line trails? 6, How do you like your bike to feel? Stable or agile?

Please feel free to call or email us if you want talk through options or get a second opinion.

Buying your new G1

Not so fast! You might be looking for the click to buy button by now,  It’s understandable after scrolling through the G1 GPI product features. If you’re ready to buy then we kindly ask you to submit a build request form below.

Please Include your order details:

Start with your frame configuration- Frame size, wheel size, if you want specific mutator set up.

Then your frame finish & extra love kit colour choice.

Finally move onto your build kit choice: i.e. Frame & Gearbox or Rolling chassis or Full Build.

Please also add any other specific details for your build and list any questions you have.

We will get back to you within 24hrs with an itemised estimate and answers to your questions.

New orders have a production lead time of approximately 10 weeks.