Chain Size & Gearing Calculator
Chain Size & Gearing Calculator
Scale your sprockets for a different chain pitch. Then fine-tune the tooth counts to compare your gearing.
Current setup
New setup
Rounds each sprocket to the nearest whole tooth. You can adjust either value below.
Sprocket size comparison
| Pitch diameter | Current | New |
|---|
Pitch diameter is measured through the chain pin centers, not across the tooth tips.
Nearby gearing options
Keep your selected new front sprocket and compare nearby rear sizes.
| Front / rear | Ratio | Gearing change |
|---|
What changes?
The rear-to-front tooth ratio sets your final-drive gearing. Chain pitch sets the physical size of the sprockets. A 520, 525, or 530 conversion keeps the same gearing and pitch diameters when tooth counts stay the same.
Different chain sizes still require correctly matched sprockets. Verify fitment, clearance, chain length, and the chain maker’s application rating before ordering.
Chain sizes & calculation details
| Chain | Pitch, mm | Inner width, mm |
|---|
Scaled teeth = current teeth × current pitch ÷ new pitch. This preserves nominal chain travel per sprocket revolution before whole-tooth rounding. Pitch diameter = pitch ÷ sin(π ÷ teeth). Ratio = rear teeth ÷ front teeth. Gearing change = (new ratio ÷ current ratio − 1) × 100. Speed change assumes unchanged transmission, tire, and engine RPM; it is not a top-speed prediction.
Nominal dimensions: D.I.D chain specifications. Scaled sizes are mathematical comparisons, not a list of available parts.