Specialized Crux 4 Geometry, Sizes & Bike Fit

Specialized Crux 4 geometry (2025) — compare stack, reach, and every supported size, then open the TrainCraft calculator with this bike preselected.

Supported sizes

49, 52, 54, 56, 58, 61

Family

race geometry

This bike leans toward an aggressive front end, faster steering, and a more performance-oriented position.

What to compare

Stack, reach, setup

Use this guide to compare stack, reach, and gravel-specific front-end assumptions before choosing a frame size.

Check my size with measurements Compare geometry first View original geometry source

Quick size check

What Specialized Crux 4 size fits you?

Get an instant frame estimate, then continue into the full fit report to check cockpit reach, bar drop, and setup risks before you buy.

No account needed for this check. The full report keeps this bike preselected.

Geometry and size breakdown

Use the geometry table as context, then enter your measurements above before opening the full fit report.

Size	Stack	Reach	Top tube	Head tube	Stem	Crank	Size check
49	530 mm	375 mm	512 mm	100 mm	70 mm	165 mm	Check with my measurements
52	547 mm	382 mm	539 mm	115 mm	80 mm	170 mm	Check with my measurements
54	560 mm	388 mm	549 mm	130 mm	90 mm	172.5 mm	Check with my measurements
56	578 mm	397 mm	568 mm	147 mm	100 mm	172.5 mm	Check with my measurements
58	598 mm	405 mm	582 mm	167 mm	110 mm	175 mm	Check with my measurements
61	621 mm	415 mm	599 mm	190 mm	110 mm	175 mm	Check with my measurements

How to use this guide

Start with the size table to narrow the geometry range you actually want. Then open the calculator to compare that geometry against your body dimensions, flexibility, and fit priorities.

The TrainCraft bike fit tool models saddle height, cockpit reach, and bar drop using the frame geometry plus stock cockpit assumptions for the Specialized Crux 4.

That is more useful than a generic height chart because two sizes can both fit your height while requiring very different stems, spacers, or saddle positions.

FAQ

What sizes are available for the Specialized Crux 4?

TrainCraft currently tracks these Specialized Crux 4 sizes: 49, 52, 54, 56, 58, 61. The calculator uses each size's published geometry and stock cockpit assumptions to compare fit outcomes.

Can I use the TrainCraft calculator for Specialized Crux 4 sizing?

Yes. Open the calculator from this page to preload the Specialized Crux 4, then compare sizes against your body measurements, fit priorities, flexibility, and riding posture preferences.

What should I compare on the Specialized Crux 4 before picking a size?

Start with stack, reach, effective top tube, and the stock stem/crank setup. TrainCraft uses those numbers to estimate cockpit reach, bar drop, saddle position, and how much adjustment headroom each size leaves.