Examples
Examples
Try the starting example
- Original front sprocket (teeth)
- 15
- Original rear sprocket (teeth)
- 45
- New front sprocket (teeth)
- 16
- New rear sprocket (teeth)
- 44
- Original final reduction
- 3
- New final reduction
- 2.75
- Speed per engine RPM change (%)
- 9.090909
- Engine RPM at same road speed change (%)
- -8.333333
Try another scenario
- Original front sprocket (teeth)
- 15
- Original rear sprocket (teeth)
- 45
- New front sprocket (teeth)
- 14
- New rear sprocket (teeth)
- 48
- Original final reduction
- 3
- New final reduction
- 3.428571
- Speed per engine RPM change (%)
- -12.5
- Engine RPM at same road speed change (%)
- 14.285714
Calculation method
Calculation method
Original final reduction
oldRear/oldFront.
New final reduction
newRear/newFront.
Speed per engine RPM change (%)
100*((newFront/newRear)/(oldFront/oldRear)-1).
Engine RPM at same road speed change (%)
100*((newRear/newFront)/(oldRear/oldFront)-1).
Symbols and units
- a
- Original front sprocket (teeth)
- b
- Original rear sprocket (teeth)
- c
- New front sprocket (teeth)
- d
- New rear sprocket (teeth)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Assumptions & limits
Assumptions & limits
- Ideal final-drive ratio comparison holding tire rollout and all other gearing constant. No top-speed prediction, fit, chain length, speedometer or road legality inference. Supported limits: Positive integer tooth counts; 1..1000.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.