Trek describes the Fuel+ MX as its “pop-happy” e-MTB, and the setup explains why: a big 29 in front wheel to roll over things, and a smaller 27.5 in rear wheel that’s quicker to move around. The Trek Fuel+ MX 9.9 X0 AXS Gen 2 is the one MX build Trek has published full specs for, and at 41.94 lb it’s the lightest Fuel+ with a listed weight. I haven’t ridden it. I’ll compare it with its Fuel+ siblings, the Slash+ and the Aventon Ramblas I filmed. Everything here comes from Trek’s product pages, checked on Oct 28, 2026 and linked at the bottom.
The mixed-wheel Fuel+
The Fuel+ Gen 2 is one carbon frame sold three ways. EX is the do-it-all trail bike with 29 in wheels, LX is the long-travel version, and MX sits between them on travel, with 150mm in the rear and a 160mm fork.
What makes the MX different is the wheel setup, called a mullet or MX setup: a 29 in wheel up front and a 27.5 in wheel in the back, in every size from S to XXL. The frame makes this possible with an interchangeable lower shock mount and rocker link, and Trek’s parts list describes the frame’s travel as adaptable from 145 to 160mm. A flip chip in the lower shock mount changes the leverage rate if you want more progression.
Motor and battery
The MX uses the same TQ HPR60 as the rest of the Fuel+ family: 60 Nm, 250W continuous, 350W peak. Trek says it kicks in at a lower cadence than the motor it replaces. Assist runs to 20 mph (Class 1), with no throttle listed.
The removable TQ battery holds 580Wh, and Trek says the frame has room for a range extender. Trek doesn’t give a range in miles. A 4A charger and a handlebar-mounted TQ color display with Bluetooth and ANT+ come with the bike.
What the 9.9 X0 AXS includes
This is a top-tier build. The suspension is Fox Factory: a 36 fork with 160mm and a GRIP X2 damper, plus a Float X shock (205 x 60mm). Shifting is SRAM’s wireless X0 Eagle AXS T-Type with an AXS pod and a 10 to 52 cassette. The brakes are SRAM Maven Silver 4-piston on 200mm rotors.
The wheels are Bontrager Line Pro 30 carbon, which Trek backs with a lifetime warranty for the original owner and a two-year Carbon Care program that repairs or replaces damaged wheels. The tires are a Maxxis Assegai 29 x 2.5 in up front and a Minion DHR II 27.5 x 2.5 in Double Down casing in the rear. You also get a Race Face ERA carbon bar (800mm) and a wireless Fox Transfer NEO dropper (150mm in S, 175mm in M, 200mm in L to XXL).
Trek lists 41.94 lb in size M, with sealant and no tubes.
Two listings, two prices
Trek lists the MX 9.9 X0 AXS twice. The listing with full specs was on sale for $8,999.93, down from $9,999.99, on Oct 28, 2026. It showed sizes M and XXL available and S, L and XL out of stock, in one color. A second listing at $9,999.99, build to order, had no spec summary that day.
Trek also lists an MX 9.8 Eagle 90 ($8,699.99), an MX 9.8 XT Di2 ($8,499.99) and an MX 9.8 XT ($7,999.99), but it hadn’t published full specs for them on Oct 28, 2026, so I’ve left them out.
Frame details
The OCLV Mountain Carbon frame has downtube and shuttle guards, internal routing, a ZS headset that accepts angle-adjust cups, Trek’s Active Braking Pivot and a UDH derailleur hanger standard. Max fork travel is 170mm, max rotor size is 203mm and max tire size is 29 x 2.50 in. The total weight limit is 300 lb, including the bike.
How it compares
Against the Fuel+ EX 9.9 X0 AXS Gen 2: same frame, motor, drivetrain, brakes and carbon wheels, with 145mm rear, a 150mm fork and 29 in wheels at both ends in M and up. It’s $9,999.99 and build to order, with no published weight. On sale, the MX 9.9 is $1,000 less.
Against the Fuel+ LX Gen 2: 160mm rear, 170mm fork, 29 in wheels at both ends, from $8,499.99 with no published weight.
Against the Trek Slash+, which I haven’t ridden either: also HPR60, 580Wh and mixed wheels, with 170mm of travel. The Slash+ 9.9 was $9,499.93 on sale ($12,499.99 regular) at 48.13 lb. On paper, the MX 9.9 is about 6 lb lighter for less money, with 20mm less rear travel.
Against the Aventon Ramblas, which I filmed: a hardtail with a 100 Nm motor, a 708Wh battery and a coil fork, about 54 lb in its current ADV version. It has much more torque but no rear suspension and about 12 lb more weight.
If you want full-power Trek assist instead, the Rail+ 8 Gen 5 has an 85 Nm Bosch CX and 800Wh for $5,999.99, at 54.42 lb.
FAQ
Have I ridden the Fuel+ MX Gen 2?
No. This page is based on Trek’s product pages, checked Oct 28, 2026.
What does MX mean?
It’s the mixed-wheel setup: 29 in front, 27.5 in rear, in every size.
How much does it weigh?
Trek lists 41.94 lb for the MX 9.9 X0 AXS in size M, with sealant and no tubes.
Why are there two prices?
Trek has two listings for the MX 9.9 X0 AXS. The one with full specs was $8,999.93 on sale (regular $9,999.99). The other was $9,999.99 with no spec summary, as of Oct 28, 2026.
Is there a cheaper MX?
Trek lists three MX 9.8 builds from $7,999.99, but it hadn’t published full specs for them on Oct 28, 2026.
Pros and cons (from the specs and sources)
Pros: 41.94 lb, the lightest listed Fuel+; mixed wheels in every size; Fox Factory suspension; wireless X0 AXS shifting and wireless dropper; carbon wheels with a lifetime warranty; removable 580Wh battery; $1,000 off on Oct 28, 2026.
Cons: 60 Nm is a light assist at this price; no range figure; only one MX build with published specs; S, L and XL out of stock on the sale listing; two listings at different prices can confuse ordering.
Who it’s for
On paper, the Fuel+ MX 9.9 fits riders who want a light, high-end e-MTB with a playful mixed-wheel setup and a quieter motor, and who are fine trading raw power for less weight. Shoppers in size M or XXL can get the sale price; others should check both listings or ask a Trek store.
Price
As of Oct 28, 2026, the Fuel+ MX 9.9 X0 AXS Gen 2 was $8,999.93 on sale (regular $9,999.99) on trekbikes.com. Trek’s second listing was $9,999.99.
“For you shall go out in joy and be led forth in peace; the mountains and the hills before you shall break forth into singing, and all the trees of the field shall clap their hands.” Isaiah 55:12 (ESV)
