I’ve got to hand it to GeoMetron, it really did get their first. Over the past few months we’ve seen half a dozen brands introduce gear box bikes to their ranges, complete with Gates belts to replace the trusty chain, culminating in the oh-so-cool Atherton A.200G prototype. But the little brand from the UK beat them all to the great switchover by some 18 months, after revealing the GeoMetron Pinion G2 gearbox all the way back in summer 2023.

And while the Pinion G2 I tried used a chain and mechanical shifter to provide drive and shift gears there’s now a brand new version, called the GeoMetron G1 GPI. It’s ditched its chain too in favour of that famous Gates Carbon belt, and now gets an electronically controlled shift lever.

The belt drive is said to be more reliable, quieter and lighter than a standard chain

The new bike – also known as the Nicolai G1 GPI in Europe – uses the latest Pinion C1.12i gearbox, 12 evenly spaced gears and a total gear ratio of 600%. It’s also completely customisable in terms of geometry and sizing, gets a choice of two different suspension travel lengths, and built bikes are available from £9,499. Oh, and it weights 18.5kg in medium, without pedals.

GeoMetron G1 GPI need to know

• GeoMetron’s new G1 GPI gets a 12speed Pinion gearbox, and now a Gates carbon belt
• Shifter is now electronic and can shifter under load or when you’re not pedalling
• Complete bike from £9,099.99 or frame only options from £5,099
• Huge sizing and a vast array of geometry adjustments available on the fly

When I said GeoMetron got their first with the gearbox bike I really meant it. Back in 2016 we tested the GeoMetron-adjusted Nicolai Ion GPI, yes it had 26in wheels but it was also rocking 155mm travel, boasted a massive 502mm reach in size large, and had an unheard of 63.5° head angle.

The latest GeoMetron G1 GPI actually gets pretty similar geometry, pointing to the fact the brand had it dead right nearly a decade ago. We’re talking about at 63° head angle (in size medium, the geometry changes depending on the bike’s size), and an almost identical 498mm reach in size large. There are now two more sizes than that bike from a decade ago, from small to XXL, and the wheelbase has grown a fair bit.

Most importantly for GeoMetron customers is the ability to tweak the geometry, with the brand’s Mutators on the seat stays and chainstays letting you fine tune BB height, rear triangle length and head angle.

Change the shock mounting position and you can toggle the G1 GPI’s travel from 162mm to 175mm

Travel is verging on downhill bike numbers on the new G1 GPI too, if you go for the full 175mm. If that’s too much it’s possible to change the shock’s mounting point on the rocker link and step it down to 162mm. And not to be outdone, the frame will take 170mm or 180mm forks.

Why go for a belt drive over the traditional chain?

According to GeoMetron the advantages are many. I calms the bike down, reduces feedback transmitted into the bike by a flailing chain, and reduces the noises coming from a traditional chain grinding on a muddy cassette. And it further reduces the unsprung mass of the rear wheel by taking the heavy chain away, compounding the gains from getting rid of the mech.

“And that is all before we come to the point of the reduced maintenance, the belt itself is maintenance free,” Sam Robson from Geometron told me. “We think it is definitely worth it to overcome the design challenges.”

The Pinion gearbox gets 12 speeds on the G1 GPI, and they’re evenly spread and deliver a 600% gear range

Gearbox details

The new bike uses a PINION C1.12i 12-speed electronically operated gearbox paired with a GATES Carbon Drive belt, with an overall gear range of 600% and consistent 17.7% gear steps. 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 10,000Km.

Geometron G1 GPI 2025 is a downhiller’s enduro bike, with huge travel… and weight too!

G1 GPI complete bike £9099.99

The built bike comes with a EXT Storia V4 G1 Spherical shock and EXT ERA V2.1 29″ 170mm 44mm offset fork. It’s got a BikeYoke Revive dropper, comes with a Burgtec Enduro m3 Stem and alloy bar, with Formula Cura 4 or Hope Tech 4 V4 brakes. A WTB Volt or Ergon SM saddle, and Burgtec Bartender Pro.

It uses Hope Fortus 30w/SC 32h rims, Hope Pro 5 hubs, and Schwalbe or Continental.

The drivetrain uses a PINION Crankset with 165/170mm cranks, a GATES Carbon Drive CDX, the PINION C1.12i gearbox and PINION TE1 E-Trigger shifter. Total weight 18.5Kg (size M, w/o pedals, factory raw)

You can get the Geometron G1 GPI as a frame and drivetrain-only build, letting you spec your own parts

Frame builds

Geometron also breaks the bike down into a multitude of buying options, which could be useful if you already have parts or want to build the bike with something specific. A frame and gearbox-only setup for £5,099. Step that up to £5,849 and you get an EXT Storia V4 shock too. For £7,224 add on an EXT ERA fork with 170mm travel. And at £7,524 the BikeYoke dropper gets included too. Finally there’s a rolling chassis with Hope wheels at £7,849