The Drag of Chain Efficiency, Part I
The quest to make the bike go faster never ends. Once the big things are taken care of, it’s time to focus on the little things. And when the little things seem dialed, it’s probably a good idea to check back on the big things, just in case something has changed. And then back to the little, just because something else might have been overlooked.
When I read about Friction Facts and their claims that variations in chains and chain lube results in a measurable difference in terms of energy cost to propel a bike, I was intrigued. Especially when part of the solution was a proprietary paraffin mix. A semi-secret sauce? How much better could high-tech old-school waxing be? I purchased the set of reports they had on offer to take a look. Turns out, the differences can be big.
This piece gets fairly technical. There’s a reason. I’m trying to explain everything on the assumption that the reader isn’t familiar with every little bit of info. And, as with watts, little things can add up to make big differences.
Chain and Drag
Friction Facts tested five top-of-the line ten-speed chains, with five samples each, and averaged the results. According to Friction Facts, the standard Wippermann Connex 10S1 chain, Wippermann’s lightest chain, a chain I’ve run on my bike many times, has 8.85 watts of drag straight out of the box when the five samples tested at 250w were averaged. In the tests, the 10S1 also showed the least variation from chain-to-chain, with the spread between the least efficient and most efficient a total of .45w. And when the 10S1 was relubed with light oil, the friction dropped to 7.04w at 250w. In other words, a 1.81w difference (0.724%) is found by changing lubes. And the differences are much bigger for “optimized” chains, with many of them coming closer to 5w, a whopping 2%!
In case you’re wondering, the oil used for the Friction Facts tests was a non-cycling oil. Specifically, an electric motor oil from a company that doesn’t make or market cycling-specific lubricants. This was a deliberate choice, both to show no favoritism to any bike-specific brand, and because the oil has no additives, like Teflon, that could potentially affect results.
1.81w is pretty small, but all things being equal, can result in some noticeable differences. To give a sense of what kind of difference 1.81w makes, we went to Analytic Cycling. If you haven’t been to the site, it is a must-visit of the tech set. The calculators are incredible.
Utilizing the Speed For Given Power calculator, you can quantify what 1.81w means. Because it is in a part that directly propels the bike, the wattage can be directly added to the rider’s power. Assuming the default frontal area, average drag coefficient, riding at sea level on a typical asphalt road and no wind, a 150lb rider pedaling a 17lb bike at 250w goes 11.22 meters per second or 25.01mph. Take that 1.81w savings and add it to your power, and the same rider goes 11.25m/s or 25.17mph. In other words 3cm farther per second translates into .16mph increase in speed. Or .64mi in four hours—over a kilometer difference in a four-hour ride by changing chain lube. Even at an easier 200w, where the same rider is doing 10.78m/s, the rider with the lubed chain is still traveling 3cm faster every second.
This is why looking for “marginal gains” is something just about everybody should consider. Marginal gains is a term the Sky professional racing team has popularized. Essentially, it means that accruing tiny improvements, on the order of one percent or so, wherever they can be found, can add up to race-winning differences. It’s hard to imagine that people wouldn’t want the cumulative effect of small gains, even if they can barely feel them. And it’s easy to see why professional cyclists should care: ride the 80 hours or so of a Grand Tour as a time trial, that marginal savings could be worth over 20 kilometers, or almost a half-hour.
In other words, 1.81w is a big deal. Wondering if the data was reliable, I got in touch with Tom Petrie, whose company, Velimpex, imports and distributes Wippermann chains. Presumably a chain expert, I figured he might have something to say on the matter. He got back to me with a proposal. Test two Wippermann chains out in real-world conditions; see if the difference is measurable. One was the stock 10s1, the other was the stock 10s1 with the Friction Facts chain wax applied. He sent one chain directly to me, another to Friction Facts, who did their magic and sent it my way.
Jason Smith, the man behind FF, sends a report along with each chain he optimizes. The particular chain he sent had 5.51w of friction, 3.34w lower than standard, with factory lube, in the range of what he reports is possible with Wippermann, and above the 5w guarantee he has for the other chains he optimizes. But his reports indicate that he’s been unable to get the Wippermann chains down to 5w. Still, the 3.34w drop in resistance takes that same person above from going 11.22m/s to 11.28m/s. an extra 6cm per second, an extra .22mph, raising that same theoretical rider’s speed from 25.01 to 25.23mph. After four hours, you’ve gone .88mi farther.
Wippermann comes with an advantage in chain testing. Their Connex link is a tool-free, reusable master link, which makes swapping chains easy. It’s also something that Smith recommends using with all the chains he optimizes. This way, you can warm up on your standard chain, swap out the standard chain for the optimized one in less than a minute, put in the rear disc, clean hands, and head for the start house.
I started with the two Wippermann 10S1 chains. My basic idea was: take them out of the box, size them identically and then alternate chains on repeated tests. Do many indoor sessions so the tests are repeated over time, and then take the optimized chain out and see how long it goes before it starts squeaking. Smith actually runs the chains he optimizes for 20 minutes before sending them out, so there isn’t a need for any break-in period. And, as he believes the treatment is good for around 200 miles, there’s little reason to waste any mileage on breaking it in. Since that chain wasn’t going to be cleaned, we also started with the standard chain straight out of the box, no lubing or cleaning. It would be our daily chain and would only get wiped down, if necessary, before an indoor session, and only lubed when absolutely necessary. This way, I figured I’d be treating the regular and optimized chains the way people looking for performance advantages would be.
The plan was to ride with them doing repeated runs on my Kreitler rollers at three different loads: 150, 250, and 300 watts, to see if I could find any differences at the different power numbers and if those differences could change depending on load. I’d do one chain for a half hour. Then the other.
The only way to know if the differences, assuming there were differences, are actually there, is to control as many variables as possible. I used a digital pressure gauge to make sure the tires were within 1psi of 105psi for every ride. I made sure the room was within a narrow temperature range of a few degrees Fahrenheit. I let the bike sit in the room for at least 15 minutes before starting to make sure the power meter was properly acclimated. I zeroed out the power meter offset before each test. I either used the rollers with no resistance or with the headwind unit attached and the gate closed.
A perfect scenario would have been to have a test bike just for riding indoors. But I went with my regular road bike that was going indoors and out in the winter. So there could be variations on bearing drag and the wear of the tires could potentially make a difference. I started the test on Vittoria Rubino Pro tires, but as they looked pretty worn and was worried they wouldn’t last through the test period. So, after a few runs, I swapped in Specialized Armadillo Elites, a nice slow super-durable tire.
I also ended up having to send back my Quarq Cinqo and replaced with a Quarq Elsa. This was a potential boon, as the Elsa is supposed to be more accurate than the Cinqo. But here you’ll see the limitation of testing with a powermeter. The Cinqo has a claimed accuracy of +/-2%, a 4% potential variation. Assuming +/- 2%, 3.34w is equal to the variation at 83.5w of power. The Quarq Elsa has a claimed accuracy of +/- 1.5%, where the margin of error spread equals the power savings at 111.3w. And after we changed chain rings and tested the accuracy thereof, we ended up recalibrating the Elsa.
The idea of testing out the chains at three different loads, 150, 250, and 300 watts is to find if the change in load could result in any differences. I ended up riding at 154w and 247w, and the 300w ended up being a bit too optimistic in terms of what I could consistently hold for fifteen minutes.
I took the chains out of the boxes, sized them, and then kept them separated. They’re easy to tell apart at the start. One has wax flakes all over it and the links feel stiff to the touch. It’s a bit hard to believe the chain is faster that way. But, as I started to pedal, the wax flew off so quickly on the first run that there was no need to clean it. The other one was slightly greasy. I left it as is.
Tune in tomorrow for Part II.