Spicer and many of his contemporaries have proved that larger sprockets are more efficient at transferring power. In the case of Spicer’s experiments, a 52-11-tooth set-up, cycling at 175w, had an efficiency rating of 95.5%. That figure rose to 98.2% when using 52-21t. Why the discrepancy? It’s primarily down to the less extreme radius of rotation, so remember: if you can generate the same power using a large chainring and large-sprocket combination compared to a small chainring/small-sprocket combination, go large. Here’s some background reading.
The power savings from the chain are the greatest you can make losses of around 7-10watts of energy due to friction. That’s the bad news. The good news is it’s the easiest component to reel in those lost watts. At a basic level, simply wiping and lubing your chain before each ride can cut losses by an incredible 5w. As a reference point, 1w equates to around a 30-seconds saving over a 112-mile bike ride. So if you are going long and hitting that 112 figure, you’ll save a mind-boggling 2:30mins. Which lube you use also impacts on performance. While all achieve the similar role of filling the gaps in the links that’d normally be filled by grime and dirt, lower-viscosity lubes have proven to be more efficient – far more efficient than factory lube that’s used on the bike as that might be designed for durability more than pace. Read our feature on regular chain mantenance and see the video here.
Tension of the chain also impacts efficiency. Again drawing on the work of Spicer, he showed that higher chain tension was more efficient than lower tension. More specifically, 98.6% efficiency was measured at a chain tension of 305N compared to just 80.9% at 76.2N tension. It’s another reason why a large plus large chainring/sprocket combination is more efficient than a small/small when generating the same power output.
You’d be forgiven for thinking therefore that new chains would the most efficient as they have less ‘give’ in them, but think again. Research shows that chains that have been run-in slightly are the most efficient, gains improving as the first few hours roll by. So if you are buying a new chain for your goal race, warm it up for a few hours in the build-up week to save another 0.5w.
BB and derailleurs
The bearings in your bottom bracket can also cost you a further 6-8w in energy. Ceramic bearings are proven to run with less friction but simply greasing the BB on a regular basis can ensure similar savings, as well as increasing the component’s longevity. You should also play around with your derailleurs. Swap out your parochial pulleys that feature simple bushings with good-quality versions that feature steel bearings. A further 1.5% saving has been measured with this basic change.
The principles we’ve explored apply across all chains – 9, 10 and 11-speed systems and are relatively easy to apply to great, ongoing gains – now go and ride!