Trek Fuel+ MX 9.8 XT Di2 Gen 2 – TQ HPR50 Motor, Mixed Wheel, Shimano XT Di2, 3 Trail Configurations

The Trek Fuel+ MX 9.8 XT Di2 Gen 2 is the mid-specification build in Trek's Fuel+ MX e-MTB range — the mixed-wheel platform in the Gen 2 Fuel+ family. The MX designation refers to the mixed-wheel setup: a 29-inch front wheel paired with a 27.5-inch rear wheel. This combination gives the bike the rollover capability and straight-line stability of a 29er at the front, while the smaller rear wheel allows a lower bottom bracket, shorter chainstays, and a more agile, playful rear end — particularly beneficial for technical, tight trail riding and riders who find full 29er geometry too long or unwieldy. The motor is the TQ HPR50 — a compact, lightweight mid-drive unit producing 50Nm of torque via a harmonic pin ring drive, significantly smaller and lighter than conventional e-MTB motors with lower drag when unassisted. The frame is 900 Series OCLV Carbon, Trek's highest-grade carbon construction, made in Germany. Like all Gen 2 Fuel+ builds, this bike features three adjustable trail configurations.

Shimano XT Di2 electronic shifting provides precise, reliable, button-activated gear changes that are consistent regardless of conditions and require no cable tension adjustment. The system is customisable via the Shimano E-TUBE app for shift timing and multi-shift functions. Available in 5 sizes (S, M, L, XL, XXL) and 3 colours: Carbon Smoke/Lithium Grey Marble, Gloss Navy Smoke/Matte Trek Black, and Lichen Green/Keswick Green Splatter. For the top-specification MX build with SRAM X0 AXS wireless shifting, see the Trek Fuel+ MX 9.9 X0 AXS Gen 2. For the mechanical shifting MX build, see the Trek Fuel+ MX 9.8 Eagle 90 Gen 2. For the full-29er platform, see the Trek Fuel+ LX 9.8 XT Di2 Gen 2. Browse our full e-mountain bike collection.

What It's Good For

• Technical trail and enduro-style e-MTB riding — mixed 29"/27.5" wheel setup
• Riders who want 29er rollover at the front with a more agile, playful rear end
• TQ HPR50 motor — compact, lightweight, natural power delivery with low drag
• Shimano XT Di2 electronic shifting — precise, reliable, condition-independent
• 3 adjustable trail configurations — geometry tunable to trail type and preference
• 900 Series OCLV Carbon frame — Trek's highest-grade carbon, made in Germany
• 5 sizes: S, M, L, XL, XXL
• 3 colours: Carbon Smoke/Lithium Grey Marble, Gloss Navy Smoke/Matte Trek Black, Lichen Green/Keswick Green Splatter

What It's NOT Good For

• Road or urban riding — aggressive trail MTB geometry and tyres
• Riders wanting wireless shifting — see the Fuel+ MX 9.9 X0 AXS
• Riders who prefer a full 29er setup — see the Fuel+ LX 9.8 XT Di2 for the full-29er platform

Frequently Asked Questions

What is a mixed-wheel setup and what are the benefits?
A mixed-wheel (MX) setup pairs a 29-inch front wheel with a 27.5-inch rear wheel. The 29er front wheel rolls over obstacles more easily and provides greater straight-line stability and traction. The smaller 27.5-inch rear wheel allows a lower bottom bracket height, shorter chainstays, and a more compact rear triangle — making the bike feel more agile and playful through tight corners and technical sections. The MX setup is particularly popular with shorter riders who find full 29er geometry too long, and with riders who prioritise technical trail agility over outright speed.

How does the Fuel+ MX differ from the Fuel+ LX and Fuel+ EX?
All three share the TQ HPR50 motor and 900 Series OCLV Carbon frame. The key differences are wheel size and travel: the EX is a shorter-travel trail bike on full 29er wheels; the LX is a longer-travel trail/enduro bike on full 29er wheels; the MX uses the mixed 29"/27.5" wheel setup for a different handling character. Choose the MX if you want the mixed-wheel feel; choose the LX for maximum travel on full 29er wheels.

What are the three trail configurations?
The Fuel+ MX Gen 2 frame includes a geometry adjustment system allowing the head angle, bottom bracket height, and chainstay length to be adjusted between three distinct positions, changing the bike's handling character from more upright and playful to longer and slacker. Switching requires basic tools and takes approximately 15–20 minutes.

Can I customise the XT Di2 shifting behaviour?
Yes — Shimano XT Di2 can be customised via the Shimano E-TUBE Project app (iOS and Android), allowing adjustment of shift timing, multi-shift configuration (multiple gears per button press), and junction box settings. The app connects via Bluetooth and is straightforward to use.