It’s possible to do just about everything from a smartphone these days, and now you can even determine the length chain you need when fitting a new one to your bike using the free Chain Length Calculator.
The app is quite simple, and uses the Park Tool "Rigorous Equation" method to determine the correct length of chain for any given gear combination. The app, currently only available on Android-powered smartphones, requires you to simply input your transmission type (geared or singlespeed), chainstay length and a gear combination. The app then gives you a suggested chain length expressed as a number of links. All you do then is measure out your chain, trim it to length and install it onto your bike.
Riding through the winter places a lot more strain on the drivetrain of a bicycle, especially if you cycle most days and through all weathers. As such, it's prudent to replace a chain before it begins to wear out the cassette and chainring, doing this can save you money in the long run. With this handy app at least you won't have any doubt about how long the new chain needs to be when you fit it.
Of course, you could just measure your new chain alongside your old chain and get the right length. But if you're building up a new bike from scratch and don't have an old chain to measure your new one against, this app would be ideal for getting you the right length for your new build. Plus of course your old chain might not be the optimum length for your drivetrain, if you had to shorten it as an emergency road side fix (or somebody eles did) or whoever fitted it the first time simply got the length slighly wrong.
It’s only available on Android (they’ll release it onto Apple iOS if they get enough interest) and is free to download at https://play.google.com/store/apps/details?id=me.afwd.clc
David worked on the road.cc tech team from 2012-2020. Previously he was editor of Bikemagic.com and before that staff writer at RCUK. He's a seasoned cyclist of all disciplines, from road to mountain biking, touring to cyclo-cross, he only wishes he had time to ride them all. He's mildly competitive, though he'll never admit it, and is a frequent road racer but is too lazy to do really well. He currently resides in the Cotswolds, and you can now find him over on his own YouTube channel David Arthur - Just Ride Bikes.