Every year’s Tour de France seems to have a standout piece of tech that everyone is talking about, and this year it seems to be these goofy looking oversize rear derailleur pulleys. If you’re a normal person, you’ve probably never given a second thought to your derailleur pulley. If you work for CeramicSpeed it’s something you think about a lot.
The whole idea behind the oversize pulley is to reduce friction in the drivetrain. Less watts wasted there, means more watts being translated to speed. Every drivetrain operates in essentially the same way, a chain winds its way from the chainring, over the cassette and into the pulley system of the rear derailleur. The tightness of the angles, in which, causes friction in the chain.
The purpose of the oversize rear derailleur pulley is to open those angles up and reduce friction. There are also some high efficiency bearings along for the ride as well.
According to CeramicSpeed that combination results in a savings of 2.4 watts at an effort of 250 watts. Essentially, a one percent efficiency savings.
Sounds reasonable enough… until we take a look at the price. The oversize wheel pulley system (OWPS) from CeramicSpeed will set you back a cool $500. Ouch. Plus, the system introduces lighter derailleur tension thanks to the longer arm which can decrease shifting performance. Double ouch.
For a 1% improvement, at what amounts to a professional cyclist’s average wattage of 250 watts, that’s a lot of dough. You can simply clean and lube your chain and gain a good 5-10 watts.
For the pros there’s no reason not to slap an oversize derailleur pulley on a bike and take the 1% efficiency gain, for everyone else $500 is better spent elsewhere.