Bike Geometry Comparison Tool
Compare the geometry of any two bikes side by side. Enter reach, stack, angles, and frame dimensions to see exactly how they differ — and what those differences mean for fit and handling.
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How to Use the Geometry Comparison Tool
- Find the geometry charts for the two bikes you want to compare. These are typically on the manufacturer's product page under “Geometry” or “Specs.”
- Select the same frame size for both bikes (e.g., both Medium or both 56 cm) to make a fair comparison.
- Enter the measurements into Bike A and Bike B. Reach and stack are required; all other fields are optional but provide more insight.
- Click “Compare Geometry” to see the full comparison table with differences, stack-to-reach ratios, and fit interpretation.
Key Geometry Measurements Explained
Reach
Horizontal distance from the bottom bracket to the top of the head tube. Determines how stretched out you are on the bike. The single most important measurement for fit comparison.
Stack
Vertical distance from the bottom bracket to the top of the head tube. Determines handlebar height relative to the pedals. Higher stack = more upright riding position.
Head Tube Angle
The angle of the steering column. Steeper angles (72–73°) give quicker steering; slacker angles (65–68°) increase stability. Road bikes are typically 71–73.5°, MTBs 63–67°.
Seat Tube Angle
Affects knee position over the pedals. Steeper angles (74–76°) place the rider further forward, common on race and triathlon bikes. Shallower angles are more traditional.
Wheelbase
Total distance between front and rear axles. Longer wheelbase = more stability at speed; shorter = more agile handling. Directly affected by chainstay length and head angle.
Stack-to-Reach Ratio
Stack divided by reach. The quickest way to compare riding positions across brands and sizes. Below 1.35 = race geometry. 1.38–1.45 = all-round. Above 1.50 = endurance.
Geometry by Bike Type
| Bike Type | Typical Reach (M) | Typical Stack (M) | Head Angle | Stack/Reach |
|---|---|---|---|---|
| Road Race | 380–395 mm | 520–560 mm | 72–73.5° | 1.35–1.42 |
| Road Endurance | 375–390 mm | 560–600 mm | 71–73° | 1.45–1.55 |
| Gravel | 380–400 mm | 560–590 mm | 70–72.5° | 1.42–1.52 |
| Trail MTB | 450–480 mm | 610–640 mm | 64–67° | 1.28–1.38 |
| Enduro MTB | 465–495 mm | 620–650 mm | 63–65° | 1.25–1.35 |
| XC MTB | 430–460 mm | 600–630 mm | 66–69° | 1.30–1.40 |
Bike fit & measurement tools
Tape measure, multi-tool, and torque wrench for translating geometry numbers into a real-world fit.
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Stanley
Stanley FatMax 25-Foot Tape Measure (33-725)
Classic 25-foot tape measure with blade-lock and 11 ft of standout - the standard tool for measuring rider height and inseam when using our bike size calculators.
$23.40
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Crankbrothers
Crankbrothers M19 Multi-Tool
19-function bike multi-tool with hex, Torx, screwdriver, and chain breaker. The go-to ride-along tool for saddle height, seatpost, and on-the-road adjustments.
$34.06
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Park Tool
Park Tool TW-5.2 Ratcheting Click-Type Torque Wrench
2-14 Nm click-type torque wrench built for bicycle stem, handlebar, and seatpost bolts. Essential when pairing with our stem length and handlebar width calculators.
$100.95
View on Amazon
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Frequently Asked Questions
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