Since our initial visit with Jason Smith of Friction Facts, we’ve amassed a laundry list of questions about how we could make our drivetrains more efficient – or unintentionally make them slower. Friction Facts will be answering many of these questions with lab testing for us, but given the current season, we started with this one: How does temperature affect chain lubricants and friction?
Fluid viscosity increases as temperature decreases, meaning that many chain lubricants essentially turn into molasses in very cold conditions. One might think thicker and goopier oils would produce more chain friction — in fact that is what Smith thought would happen — but his preliminary test suggests the opposite.
Keep your cool to go fast
Smith is building an environmental chamber to conduct more carefully controlled tests, but we asked him to conduct a simple experiment to provide some food for thought in the meantime. Four chains were tested for friction, two at 0°F, and two at 150°F. One chain was also tested at room temperature (70°F).
Before the test, four identical chains were thoroughly cleaned in an ultrasonic tank filled with solvent and then lubricated using a standard procedure with a generic additive-free lubricant. Two of those chains were then stored in a freezer and the other two were heated to 150°F, and all four were subsequently transported to the lab in insulated containers, quickly installed on the test apparatus, and then measured for friction using Smiths standard protocol of a constant 250w. Since these tests were run without the benefit of an enclosed and temperature-controlled enclosure, all of the chains gradually acclimated to ambient temperature. The peak wattage shown below indicates the amount of friction each chain created. While the room temperature chain cost 7.3w in efficiency, the cold chains averaged 7.15w while the hot chains ran about 7.99w.
|Sample run||Initial chain temperature||Peak wattage at beginning of test|
|1||72°F (room temperature)||7.30W|
Smith’s data suggests that an increase in viscosity decreases friction.
‘The results are opposite of what I speculated,’ he told BikeRadar. ‘The cold chains tested slightly better than the room temperature chain, and much better than the heated chain. I speculated the cold might increase the wattage since the lube would become more viscous and make the plates stickier. This was incorrect. Im changing my story that the lube actually does become more viscous, but this thicker lube creates a better lubrication layer between the high pressures seen in the chain sliding surfaces. Regardless of speculation and the reasons why this actually happened, the data doesnt lie.’
Just the beginning
Keep in mind that this is far from a comprehensive study: Smith used only a single lubricant, the temperature wasn’t stringently controlled, and only two sample runs were conducted per variable. Also, while the trends suggest that colder temperatures and higher lubricant viscosities decrease chain friction, the differences are still very slight with less than a watt of swing in either direction.
That said, its interesting stuff and the initial results have planted the seeds for further investigation. Which lubricant is actually better in the cold? Which lubricants are the most temperature-stable? Whats better in the cold – dry lube or wet? Some of you may be asking those questions just out of curiosity but pro teams and riders are certainly taking a more pointed interest in the topic for obvious reasons.
We have much more to come. Stay tuned.