Trek Marlin Gen 3 Frame Set

Marlin Frame Set is a lightweight aluminium frame ready to be built into the perfect easygoing trail bike. It's loaded with all-new geometry that's more capable than ever, ideal for gaining confidence and speed on the singletrack.

You're new to mountain biking and want a confidence-boosting bike that's built to handle the trail, and love the idea of putting together your own dream bike build. You're new to mountain biking and want a confidence-boosting bike that's built to handle the trail, and love the idea of putting together your own dream bike build.

A lightweight aluminium frame with internal routing to protect your cables and keep your bike looking sleek, plus modern geometry that ups confident handling in varying trail terrain. Plus, a Thru-Skew rear axle that is safer, simpler and stronger than standard quick-release. A lightweight aluminum frame with internal routing to protect your cables and keep your bike looking sleek, plus modern geometry that ups confident handling in varying trail terrain. Plus, a Thru-Skew rear axle that is safer, simpler, and stronger than standard quick-release.

The Marlin Gen 3 Frame Set is made for taking on the trail. The modern geometry is ultra-capable, and added features - like extra tyre clearance and mounts for racks and kickstands - up the versatility. Marlin Gen 3 Frameset is made for taking on the trail. The modern geometry is ultra-capable, and added features, like extra tire clearance and mounts for racks and kickstands, up the versatility.
- The Marlin Gen 3 gives you serious trail capability with bigger tyre clearance, internal dropper post routing, ThruSkew rear axle and longer, slacker geometry that gives you more stability on steeper trails and at higher speeds Marlin Gen 3 gives you serious trail capability with bigge
- You'll get a lightweight aluminium frame that's robust enough for the ride without weighing you down You'll get a lightweight aluminum frame that's robust enough for the ride without weighing you down
- Mudguard mounts make it easy to accessorise, so your mountain bike can double as a rugged commuter Fender mounts make it easy to accessorize, so your mountain bike can double as a rugged commuter
- Marlin models in XXS and XS frame sizes have a curved top tube and a lower standover height that makes it easier for smaller riders to mount and dismount Marlin models in XXS and XS frame sizes have a curved top tube and a lower standover height that
- Internal routing looks sleek and makes adding a dropper post easy Internal routing looks sleek and makes adding a dropper post easy

Expanded size range
With 8 different sizes, the Marlin has a bike made to fit every rider. Each frame is equipped with smart wheel sizing, with XXS frames rolling on 26" wheels, and wheel sizes increasing proportionally along with frame sizes, so every rider gets the fit they need.

Trail-ready, Upgrade-ready
The secret to Marlin's popularity is a real trail-savvy mountain bike frame that's upgrade-compatible, so it can grow with you as you take on bigger trails and tougher features.

Roll stronger with Thru Skew
Goodbye open dropouts. The Thru Skewer is a better, stronger, more precisely aligned rear wheel retention system that keeps your wheel more secure than quick-release skewers while still using the standard 135 mm rear hub spacing.

A better way to produce aluminium
Starting in 2024, we began removing high-emission aluminium from our manufacturing and replacing it with low-emission aluminium made with renewable energy. By October 2025, nearly every alloy bike we make - this one included - had made the switch, driving a major drop in our footprint.