FIXED GEAR CALCULATOR
CHOOSE THE RIGHT RATIO.
WEAR THE TYRE EVENLY.
Choose the number of teeth front and rear. See the gear ratio, skid patches and estimated speed before you buy your next cog.
Your gearing
The tyre wears at 17 points
Wear is spread across many parts of the tyre. This is considerably better than a combination that always locks the wheel at the same point.
48 × 17 · 90 rpm · 700 × 28
Estimated speed. Actual rolling circumference varies slightly depending on tyre, rim and pressure.What does gear ratio mean?
The number of teeth at the front divided by the number at the rear. 48 ÷ 17 = 2.82, which means the rear wheel rotates about 2.82 times per crank revolution.
What is a skid patch?
The point on the rear tyre that touches the ground when the wheel locks in the same crank position. More skid patches spread wear across a larger part of the tyre.
Why does either foot matter?
If you can initiate a skid with either foot forward, some ratios can provide twice as many wear points. The calculator accounts for the reduced gear ratio.
How our Fixed Gear Calculator works
Choose the number of teeth on the chainring and rear cog to calculate the gear ratio, estimated speed, and number of skid patches. You can also compare nearby gear ratios and see how cadence and tire size affect speed.
A combination of 48 teeth in front and 17 in the rear gives a gear ratio of 2.82 and 17 skid patches. With 48 × 16, the gear ratio is 3.00, but the tire wears at the same spot if you always start the skid with the same foot forward. If you can skid with either foot forward, some combinations can give you twice as many wear spots.
More skid patches spread wear over a larger part of the rear tire. The calculator therefore helps you find a gear ratio that gives your bike the right feel without always putting stress on the same spot on the tire.
The tool was developed by Urban Bike Wear, an independent fixed gear specialist and bike workshop in Stockholm. We build and service fixed gear and singlespeed bikes, and use the same principles when helping customers choose the right components.
The gear ratio is only one part of a well-functioning build. Chainline, chain width, BCD, hub width, and lockring threading also need to work together. Read our complete guide to building a fixed gear.
