Trek FX geometryUrban · 2022 · 5 sizes, from XS to XL

The Trek FX is a urban bike available in 5 sizes, from XS to XL. Stack ranges from 543 to 648 mm and reach from 383 to 409 mm. Its geometry is low and long, with a racing fit. All sizes share 447 mm chainstays.

Stack543–648mm

Reach383–409mm

Head angle70.0–72.5°

Chainstay length447mm

Steep seat angle

What size FX 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 →

XSS 543 · R 383

SS 568 · R 385

MS 594 · R 393

LS 620 · R 399

XLS 648 · R 409

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	XS	S	M	L	XL
Stack	543	568	594	620	648
Reach	383	385	393	399	409
Effective top tube	528	543	563	583	613
Head tube length	115	140	165	190	215
Head angle	70.0°	70.5°	71.0°	71.5°	72.5°
Chainstay length	447	447	447	447	447
Wheelbase	1,052	1,059	1,070	1,080	1,087
BB drop	65	65	65	65	65
BB height	285	285	285	285	285
Fork offset	50	50	50	50	50
Trail	74	71	68	64	58
Standover	675	715	754	791	836
Seat tube (method not stated)	330	375	420	465	520
Seat angle (method not stated)	75.0°	74.5°	74.0°	73.5°	72.5°

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 urban 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 urban models, by stack and reach.

ModelΔ stackΔ reach

Cube Editor SLX FE · 50 cm2026−3 mm+2 mmCompare →

Cube Editor SLX · 50 cm2026−3 mm+2 mmCompare →

Cube Editor · 50 cm2026−3 mm+2 mmCompare →

Specialized Sirrus · M2026−1 mm+5 mmCompare →

Cube Nulane C:62 · L2026+5 mm−1 mmCompare →

Cube Nulane C:62 SLX FE · L2026+5 mm−1 mmCompare →

Frequently asked questions

What size FX 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 543/383 mm in size XS to 648/409 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 FX in size M?

Stack of 594 mm and reach of 393 mm, with an effective top tube of 563 mm and a head angle of 71.0°.

Is the FX a racing or an endurance bike?

Racing. In size M its stack-to-reach ratio is at percentile 33 of urban bikes: a low, stretched position.