A lot of well-dressed bicycles are wearing belts these days.  They make a clean, crisp fashion statement on the runway, the road and the bike path.  Unlike a chain (or the belt on your pants), though, the length of a bike’s drive belt can’t be adjusted.  The length of the belt depends on the size of the front and rear sprockets, and the distance between them.

Gates Carbon Drive Belt Drive Belt Length CalculatorSo how does the well-heeled bicycle owner decide what is the right belt length for his or her bike?  Fortunately, our friends at Gates have created a handy belt length calculator.  It’s an easy to use Excel spreadsheet you can download to your computer.  You can find it here. Once you arrive at the Tech Info Page, select “Belt and Sprocket Size Calculator” under the heading “Technical Manual.”  (Skip the Carbon Drive Systems Calculator also appearing on that page – it’s not nearly as useful.)

If you are setting up a single speed, calculate which combination of front and rear sprockets will give the ratio you want.  In general, a smaller front sprocket will give better clearance with the chainstay.

For internal gear hubs, consult the manufacturer’s data on ratios.  Select a combination of front and rear sprockets so that you will have the low gear you want.

Make sure your combination of sprockets and belt length work for your bike’s chainstay length.  The calculator will give you the required range of adjustment to take up belt slack.

With the right belt length, your bike will be well-appointed and give you years of carefree riding.