Trek Fuel LX Aluminium geometryMTB · 2026 · 4 sizes, from S to XL

The Trek Fuel LX Aluminium is a mtb bike available in 4 sizes, from S to XL. Stack ranges from 619 to 661 mm and reach from 418 to 498 mm. Its position sits between racing and endurance.

Stack619–661mm

Reach418–498mm

Head angle63.4–63.5°

Chainstay length437–447mm

PlantedCalm steeringSteep seat angleHigh BB

What size Fuel LX Aluminium 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 619 · R 418

MS 633 · R 448

LS 647 · R 473

XLS 661 · R 498

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
Stack	619	633	647	661
Reach	418	448	473	498
Effective top tube	552	586	621	655
Head tube length	95	110	125	140
Head angle	63.4°	63.4°	63.4°	63.5°
Effective seat angle	77.5°	77.2°	76.4°	75.9°
Actual seat angle	71.5°	71.5°	71.5°	71.6°
Chainstay length	437	437	442	447
Wheelbase	1,200	1,237	1,273	1,310
Front centre	765	801	833	864
BB drop	26	27	27	27
BB height	347	347	347	346
Fork offset	44	44	44	44
Trail	138	138	137	137
Standover	757	754	757	768
Seat tube (method not stated)	370	400	420	455

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.

Positionracing → relaxed

Steeringcalm → quick

Pedallingrearward → forward

Bottom brackethigh → low

Wheelbaselively → planted

Rear endstable → agile

Bikes with similar geometry (size M)

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

ModelΔ stackΔ reach

Trek Fuel LX Carbon · M2026±0 mm±0 mmCompare →

Trek Session · R12022+1 mm−1 mmCompare →

Cannondale Trail · LG2025−1 mm−1 mmCompare →

Specialized Demo Race · S32026−1 mm−2 mmCompare →

Cannondale Habit Carbon LT · MD2022+2 mm+2 mmCompare →

Cube FRITZZ C:62 Super · M2026−3 mm±0 mmCompare →

Fuel LX Aluminium or Fuel LX Carbon? In size M they have exactly the same stack and reach (633 / 448 mm): the difference is in the frame and build, not the position.

Frequently asked questions

What size Fuel LX Aluminium 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 619/418 mm in size S to 661/498 mm in size XL). 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 LX Aluminium in size M?

Stack of 633 mm and reach of 448 mm, with an effective top tube of 586 mm and a head angle of 63.4°.

Is the Fuel LX Aluminium a racing or an endurance bike?

In between. In size M its stack-to-reach ratio is at percentile 61 of mtb bikes: neither very low nor very tall.

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

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