Trek Check-OUT geometryGravel · 2026 · 5 sizes, from S to XL

The Trek Check-OUT is a gravel bike available in 5 sizes, from S to XL. Stack ranges from 580 to 673 mm and reach from 395 to 435 mm. Its geometry is tall and short, built for comfort. All sizes share 442 mm chainstays.

Stack580–673mm

Reach395–435mm

Head angle68.8–69.5°

Chainstay length442mm

PlantedStable rearCalm steeringHigh BBRelaxed

What size Check-OUT 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 580 · R 395

MS 617 · R 407

MLS 634 · R 417

LS 652 · R 427

XLS 673 · R 435

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	ML	L	XL
Stack	580	617	634	652	673
Reach	395	407	417	427	435
Effective top tube	564	589	597	613	628
Head tube length	94	133	149	170	193
Head angle	68.8°	69.0°	69.4°	69.5°	69.4°
Chainstay length	442	442	442	442	442
Wheelbase	1,081	1,105	1,117	1,135	1,150
BB drop	70	70	70	68	68
Fork offset	45	45	45	45	45
Trail	92	91	88	88	88
Standover	772	804	838	846	852
Seat tube (method not stated)	440	470	520	540	560
Seat angle (method not stated)	74.6°	74.2°	73.7°	73.0°	72.6°

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 gravel 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 ML)

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

ModelΔ stackΔ reach

Colnago C68 Gravel · 5702026−4 mm+2 mmCompare →

Specialized S-Works Diverge · 582026±0 mm−5 mmCompare →

Specialized Diverge · 582026±0 mm−5 mmCompare →

Wilier Triestina Jaroon · XL2027−8 mm±0 mmCompare →

Wilier Triestina Jaroon Alu · XL2024−8 mm±0 mmCompare →

Trek Checkmate Carbon · XL2025−1 mm−8 mmCompare →

Frequently asked questions

What size Check-OUT 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 580/395 mm in size S to 673/435 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 Check-OUT in size ML?

Stack of 634 mm and reach of 417 mm, with an effective top tube of 597 mm and a head angle of 69.4°.

Is the Check-OUT a racing or an endurance bike?

Endurance. In size ML its stack-to-reach ratio is at percentile 80 of gravel bikes: a tall, short position.