Bicycle Science


Here are some calculators that will help you determine how much power you can generate and what type of gears you need to get up the tough hills

What Gears Do I Need ?

The calculator below will help you determine what gears you need to get up a hill of the specified grade. Just change the default values on the fields below to match the your weight, hill grade, gears, that you want. The required power and cadence will be calculated. For reference a serious recreational cyclist can generate around 200 watts of continious power and may be able to do short stretches of 250-300 watts. You normally want to keep the cadence at least 60 or higher for efficiency.


Weight of rider plus bike (pounds) 
Hill grade (percent) 
Speed(mph) 
Required power(watts) 
Front chainring gear 
Rear cassette gear 
Cadence(RPM) 


How Much Power Can I Produce?

The calculator below will help make a rough estimate of much continious power you can produce. To use this calculator find a flat section of road on a windless day and accelerate to the highest speed that comfortable maintain for a while. Use this speed in the calculator. The drag coefficient for a normal rider is usually between 0.25(racing tuck) and 0.4 (sitting up). You can enter a head wind to see how much extra power it takes to over come the wind.


Drag coefficient 
Speed(mph) 
Head wind (mph) 
Power(watts) 

Gear Ratio

The table below can be used to calculate gear inches based in your front chain rings and the cogs on you rear cassette. Gear inches is the inches of the chain that are moved for each rotation of the pedals. For example if you in a 52 tooth ring in the front and an 11 tooth chain ring on your cassette then your gear inches are 128 which means 128 inches of chain are moved for each rotation of the pedals. This translates in to 4.7 rotations of a 27 inch wheel.

Front chain ring gears



Rear Cassette