Compare bike frames side by side, including different brands and size labels. Start with a sourced model-year preset or enter stack and reach from any two geometry charts. See the differences in millimeters before deciding which size to try.
Compare your current comfortable frame with the candidate size, even if one is a 54 and the other is a Medium. For a hypothetical example, changing from 560 mm stack / 380 mm reach to 580 / 390 puts the top of the head tube 20 mm higher and 10 mm farther forward. It does not guarantee the bars move by the same amount: stem, spacers and handlebar shape also matter.
Need a starting frame size first? Use the bike size calculator. Find model guidance in our brand size charts, then compare the exact generation and sizes here.
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.
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.
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°.
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.
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 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.
| 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 |
Tape measure, multi-tool, and torque wrench for translating geometry numbers into a real-world fit.
Stanley
Selected 30-foot FatMax tape measure for rider-height, inseam and bike setup measurements. This is the 33-730 single tool, not the previous 25-foot model or a two-pack.
Crankbrothers
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.
Park Tool
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.
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39 pre-built side-by-side bike comparisons with geometry charts
Calculate reach and stack from frame angles and tube lengths
Find the right frame size based on your body measurements
General bike sizing for road, mountain, and hybrid bikes
Dial in saddle height for comfort and power
Complete height-based sizing reference for all bike types
Load two bikes from BikeSize brand data or enter your own reach and stack numbers to compare them side by side.