Trek Fuel EX Carbon geometryMTB · 2026 · 5 sizes, from S to XXL

The Trek Fuel EX Carbon is a mtb bike available in 5 sizes, from S to XXL. Stack ranges from 624 to 665 mm and reach from 431 to 530 mm. Its geometry is low and long, with a racing fit.

Stack624–665mm

Reach431–530mm

Head angle64.5–64.6°

Chainstay length441–452mm

Steep seat angleStable rearCalm steeringPlantedRacingHigh BB

What size Fuel EX Carbon do I need?

Enter the stack and reach of a bike that fits you well and we will tell you which size is closest and how to set it up.

Stack in mm Reach in mm Compare on Fitbikefy →

SS 624 · R 431

MS 624 · R 460

LS 638 · R 485

XLS 651 · R 510

XXLS 665 · R 530

Enter your stack and reach to see which size fits you best.

Geometry chart by size

Measurements in mm and degrees, as published by Trek. The ones that matter most for choosing a size are in bold.

Size	S	M	L	XL	XXL
Stack	624	624	638	651	665
Reach	431	460	485	510	530
Effective top tube	559	589	613	651	680
Head tube length	110	110	125	140	155
Head angle	64.6°	64.5°	64.5°	64.5°	64.5°
Effective seat angle	78.2°	77.8°	77.3°	76.9°	76.4°
Actual seat angle	72.7°	72.6°	72.6°	72.6°	72.6°
Chainstay length	441	444	444	447	452
Wheelbase	1,200	1,232	1,258	1,298	1,330
Front centre	761	791	822	854	880
BB drop	34	35	35	35	35
BB height	339	339	339	339	339
Fork offset	44	44	44	44	44
Trail	129	129	129	129	129
Standover	754	747	750	755	764
Seat tube (method not stated)	370	400	420	455	475

Source: Trek official website · data from 11 Nov 2026.

Stack and reach of every size

Higher means a taller front end; further right means a longer reach. The blue dot is your search.

Character of each size

Compared with other mtb bikes. Further right means more of that quality.

XXL

Positionracing → relaxed

Steeringcalm → quick

Pedallingrearward → forward

Bottom brackethigh → low

Wheelbaselively → planted

Rear endstable → agile

Bikes with similar geometry (size L)

The closest size of other mtb models, by stack and reach.

ModelΔ stackΔ reach

Trek Fuel LX Carbon · L2026±0 mm±0 mmCompare →

Trek Fuel MX Carbon · L2026±0 mm±0 mmCompare →

Trek Fuel EX Aluminium · L2026±0 mm±0 mmCompare →

Cube Reaction C:68X SLX · XL2026−1 mm−2 mmCompare →

Trek Slash · L2024+3 mm+3 mmCompare →

Trek Fuel MX Aluminium · L2026+3 mm−3 mmCompare →

Fuel EX Carbon or Fuel LX Carbon? In size L they have exactly the same stack and reach (638 / 485 mm): the difference is in the frame and build, not the position.

Frequently asked questions

What size Fuel EX Carbon do I need?

It depends on your position, not just your height. The most reliable way is to compare the stack and reach of a bike that fits you with those of each size (from 624/431 mm in size S to 665/530 mm in size XXL). The size finder on this page shows the closest size and the stem and spacers you would need.

What are the stack and reach of the Fuel EX Carbon in size L?

Stack of 638 mm and reach of 485 mm, with an effective top tube of 613 mm and a head angle of 64.5°.

Is the Fuel EX Carbon a racing or an endurance bike?

Racing. In size L its stack-to-reach ratio is at percentile 19 of mtb bikes: a low, stretched position.

Does it have the same geometry as the Fuel LX Carbon?

In size L, yes: same stack and reach. If one already fits you, the same size of the other will put you in the same position.