Stack and Reach Input Form
Example Data Table
| Bike Type | Frame Stack | Frame Reach | Spacers | Stem | Typical Use |
|---|---|---|---|---|---|
| Endurance Road | 570 mm | 380 mm | 20 mm | 90 mm | Comfort rides |
| Race Road | 545 mm | 395 mm | 10 mm | 110 mm | Fast riding |
| Gravel | 585 mm | 390 mm | 25 mm | 80 mm | Mixed terrain |
| Touring | 610 mm | 375 mm | 30 mm | 70 mm | Loaded travel |
Formula Used
Direct mode uses known frame stack and frame reach. Estimate mode uses trigonometry. The lower head point is estimated from front center, fork length, fork rake, bottom bracket drop, and head angle. The top head point is then calculated by adding head tube length along the steering axis.
Spacer stack gain = spacer total × sin(head angle). Spacer reach loss = spacer total × cos(head angle). Stem stack gain = stem length × sin(stem angle). Stem reach gain = stem length × cos(stem angle). Final bar stack equals frame stack plus vertical cockpit gains. Final bar reach equals frame reach, minus steerer setback, plus stem and handlebar reach.
How To Use This Calculator
Choose direct mode when the brand lists stack and reach. Choose estimate mode when you want a geometry based estimate. Enter measurements in millimeters. Add spacer height, headset height, stem length, stem angle, and handlebar reach. Use target fields when comparing a new bike to a current bike. Press calculate. Review final bar stack, final bar reach, gaps, comfort ratio, and notes. Export the result for your fit records.
Stack and Reach Guide
Why Stack And Reach Matter
Stack and reach describe bicycle fit in a clean way. Stack is the vertical distance from the bottom bracket to the top of the head tube. Reach is the horizontal distance between the same two points. These values help riders compare frames without relying only on small, medium, or large labels.
Front End Height
A higher stack usually gives a taller front end. That can feel relaxed. It may also reduce pressure on hands, shoulders, and lower back. A lower stack can feel sportier. It can help a rider hold an aerodynamic position. The right choice depends on flexibility, riding style, and comfort.
Cockpit Length
Reach controls how stretched the cockpit feels before stem and handlebar choices are added. More reach can feel stable and aggressive. Less reach can feel upright and easy to manage. Stem length, spacer height, handlebar reach, and hood position can change the final hand location.
Calculator Purpose
This calculator accepts frame and cockpit inputs together. It can estimate base frame position, adjusted bar stack, adjusted bar reach, fit gaps, and a simple comfort note. The direct mode uses known frame stack and frame reach. The geometry mode estimates them from head tube length, head angle, bottom bracket drop, wheel radius, and front center style measurements.
Practical Fit Advice
Use the outputs as a planning guide. A bike fit session is still useful for pain, injury history, racing goals, or unusual proportions. Small changes matter. Ten millimeters of spacer change can be noticeable. A shorter stem can improve handling for some riders, but too short can make steering feel quick.
Keep Better Records
Keep records when testing bikes. Export each calculation and compare values later. Note saddle height, saddle setback, crank length, shoe choice, and handlebar model. These items influence how the numbers feel on the road.
Final Fit Check
Good fit is not only about matching a chart. It is about repeatable comfort, steady control, and efficient power. Start with known measurements. Change one variable at a time. Test the result on real rides. Then keep the setup that feels balanced during long efforts. For online comparisons, enter manufacturer geometry carefully. Some brands measure to the top cap, while others use bare frame points. Check diagrams when possible. Consistent measurement sources reduce confusion and make future choices easier for you today.
FAQs
1. What is bike stack?
Bike stack is the vertical distance from the bottom bracket center to the top center of the head tube. It describes front end height.
2. What is bike reach?
Bike reach is the horizontal distance from the bottom bracket center to the top center of the head tube. It helps compare frame length.
3. Is bar reach the same as frame reach?
No. Frame reach describes the frame only. Bar reach includes spacers, headset height, stem length, stem angle, and handlebar reach.
4. Which mode should I use?
Use direct mode when the manufacturer lists stack and reach. Use geometry mode when you only have frame and fork measurements.
5. Why do spacers reduce reach?
Spacers rise along the angled steerer tube. That movement usually goes upward and slightly backward, so effective reach becomes shorter.
6. Can this replace a bike fit?
No. It helps compare setups and plan changes. A trained fitter is better for pain, injury, racing, or complex fit issues.
7. What does comfort ratio mean?
Comfort ratio compares final bar stack with final bar reach. Higher values usually feel more upright. Lower values usually feel more aggressive.
8. Why export results?
Exports help track different bikes, stems, spacers, and bars. Saved records make future comparisons easier and reduce repeated measurements.