 not to sound mean on SRAM. I do love a lot of what SRAM do and have by need, but the chains do tend to be not the fastest. This is part two of my series on drivetrain efficiency with Adam Caron of Zero Friction Cycling. In part one, we discuss bicycle chain lubricant, and while an entire video talking about chain lube doesn't seem incredibly fascinating at first, the lube that you use actually has the biggest impact on your drivetrain's efficiency and can save you a handful of watts. That being said, the other components of your drivetrain have an effect on its efficiency as well. For example, we get into the chain itself and which chain manufacturers produce the most efficient and least efficient chains. And yes, we will be explicitly naming these companies in this video. I just hope we have a good lawyer, man, because SRAM is not gonna be happy about this one. We also discussed the other components of the drivetrain, such as chain rings, cogs, bearings, et cetera. Yes, all of these components have an effect on the drivetrain's efficiency and Adam gave some very nuanced answers here that I found fascinating. Let's get into it. But moving on from chain lube, let's talk about the actual chain itself. And are there chains that are faster than other chains or are all chains kind of the same efficiency? Yeah, no, that's a great one. That's been a fun little area as well. So absolutely there's quite a big difference between chains. So it can be between sort of mostly between chain brands as opposed to chain models as such. For instance, at the fastest end, we've got chains like a Shimano Durace 11 Speed, the new Campi 12 Speed there, kind of the fastest chains tested. So now I don't do outright efficiency testing. So for chain efficiency, I rely on SRAMX Speed, the Denmark Research Lab there. So they test chains so that they know what chains to use for their UFO chains. And it took me a long time. So I always had the data, but it took me a long time to convince them to allow me to make that data public because obviously they didn't want to upset manufacturers. So only about midway through last year, they allowed me to actually publish sort of broadly the test data that they have on chains. So typically, and not to sound mean on SRAM, I do love a lot of what SRAM do and have by near, but chains, the chains do tend to be not the fastest, can tend to be super long lasting, but just not that fast compared to the ones at the top end. So like for instance, your access road chains typically will be around sort of the five and a half watt mark as opposed to a three watt mark. So you're sort of giving up a couple of, you know, sort of two and a half watts there. So it's a fair bit in just in chains. And correct me if I'm wrong, but some of the higher end SRAM chains are actually even worse than the lower end SRAM chains. And the newer, the newer flat top chains seem to be worse. Am I wrong about that? Or is that correct? The flat top chains, I guess I'd say are similar to their previous sort of your Red 22 or your 11 speed X-X1, they're just not fast. So they're still sort of staying around that sort of five and a half, six watt mark. Eagles are a bit slower again. So the eagle chains are super long lasting, just not fast. But yeah, with SRAM, so typically low friction coatings are put on more components inside the chain, the higher level the chain you go. So for instance, with Shimano, a Durace chain is going to be faster than an old Tegra because it has that silk tech low friction coating on more parts. SRAM, it has been a little bit confusing. So for instance, their force level chain for access road is faster than their Red level by half a watt and their X-01 Eagle chain is half a watt faster than their X-X1 chain. And we don't really have an explanation as to why. We've got some sort of guesses, but we don't really know why. And it is, that's really the only case we've seen where the top level is not sort of faster than the next level down. And so yeah, so if you look at like, say SRAM X-speed, their UFO chains are force level, not Red level. I don't want to pick on SRAM too much. There's a lot of things that SRAM is doing that I like. I like the fact that their electronic shifting is wireless, for example. I have Shimano on my road bikes and my gravel bikes, but I actually have SRAM on my mountain bikes. I don't use a SRAM chain, but for somebody who's got a SRAM drivetrain, do you have a recommendation as to what chain they can run? Yeah, absolutely. So Eagle off-road, that's pretty easy. So the YBN 12-speed chain is a great go fast option for the Eagle that works absolutely beautifully on the Eagle. So like the iTrain on XX1 chains, or say you run an XX1 or XO1 chain if you're on Eagle for training because they are so incredibly wear-durable. There's nothing remotely like them in terms of wear resistance. And then you run something like a YBN for your race chain. When it comes to Axis Road, that is more tricky. So Axis Road is a new standard. They are thinner, both internally and externally, versus all other 12-speed chains, and they have oversized rollers. So obviously the cassette profile and chain ring profile is made to, I guess, run that larger roller size. So we do have, so both YBN and KMC do claim that their 12-speed chains are compatible with all 12-speed systems, including Axis Road. I'm really hesitant personally though to recommend that people do that. I mean, you can definitely try it, just be careful because my fear, aside from the fact that your tuning needs to be extremely precise because the chain is wider, my fear is that the cassette and the chain rings, when you're running a chain with normal size rollers, not oversized rollers, to the drivetrain, it is going to be like you're running a new chain on really worn components. And then you find that it's jumping under load either in a lot of cogs or worst cases, going to jump off the chain ring under stand-up power, especially like a stand-up sprint. Yeah, definitely try if you wish, but just be careful. Don't go over the handlebars, please. Have a hot date with the asphalt. So, yeah. All right, so chains are obviously probably the biggest factor in reducing friction in your drivetrain, but let's talk about other aspects of drivetrain efficiency. Things like a one-by versus two-by, small cogs versus large cogs, ceramic bearings. How much do these other factors play into the efficiency of the drivetrain? Before we sort of delve into those, it's kind of really important, I guess, to understand that the faster your chain is, the less of the penalty you're going to have for things like cross-chaining or smaller rings and cogs. The slower your chain is, the greater the penalty you're going to have. So if you've got, for instance, just a whatever drip loop from, that's whatever was on the shelf of the bike store, and it's become a bit contaminated and you're running a 10-watt chain, when you cross-chain that, then you've got a lubricant that's quite gritty and abrasive and high loss. So you're going to pay a pretty big penalty for that. If you've got a three to four-watt beautiful wax chain, your penalty is very low. Again, just focusing on your chain efficiency is going to give you some pretty big wins. Smaller rings and cogs, it depends on what you're talking about. Like if you're talking about road and time trial, obviously, generally, you want the biggest sort of ring and cogs set up. So again, not to pick on SRAM, but then move to smaller rings and the 10-toothed cog for road. From an efficiency perspective, we strongly disagree with, and I hope that one day SRAM will sort of move away from that. And just even make their sort of 54 38 ring option, not so horrendously expensive for everyone to try to get onto. Yeah, personally, I'd like to see manufacturers go in the opposite direction, bigger cogs and bigger chain rings. Yes. So, I mean, you see it more focused on in like time trials where obviously they're running really big rings. A good example is I guess more back in the early days when it was sort of 11 speed, you know, Tony Martin, he would often run an 11-32 cassette and like a 62-tooth chain ring. And it's not because he needs the 60-11 cog, you know, because it's just so tall. What he wants is to be able to hang onto that big ring really well. For the gear ratios that he's going to need on a particular course, the aim is obviously to have a fairly straight chain line, say 80% of the time, you know, for the bulk of the time. And so the cross-chain is going to be a lot less and the wider range cassette will often shift the cogs that you need. And the way this comes into play, not only to save the time trials, but even if you're on, say, a one-by-set up and you've got an event that is going to have a lot of climbing and really hard climbing. So, stereotypically, your larger rings are going to be more efficient than a smaller ring because you've got less articulation at the ring. You're going to be running a larger cog for a given gear inches, so you've got less articulation at the rear. And because there's less leverage of the crank arm over the stop point, which is the chain on the chain ring, there's less chain tension in a larger ring for the same power. If you're doing 250 watts at 100 cadence or 90 cadence in a 50-tooth chain ring versus, say, a mount bike 32-tooth chain ring, same power, same cadence, there's going to be more tension or load on the chain in the smaller chain ring for that same power because of the leverage of the crank arm over the chain. So you've got, you know, on a larger ring, you've got less articulation at both ends and it's under lesser tension. So you've got kind of three things all adding up to give you lower losses versus a smaller chain ring, which again is why they're running the biggest they can in time trial stuff. However, if it's, say, a off-road event and you're going to be doing a lot of climbing, so in theory it's like, cool, do I want to run a 34 because I want to run this nice big chain ring and I can get away with that okay because I've got a 50 or a 52-tooth cog that I can, you know, get up that hill okay, but I'm going to do a lot of climbing in that combination. You've got to remember that the larger you go on the front and the larger you go on the rear, that makes your chain line more and more extreme. You can imagine if you had, say, like an 82-tooth ring and an 82-tooth cog, your chain line's going to be damn near 45 degrees, so the larger you're going at each end, you are making your chain line more extreme, which is going to give you greater penalty and greater losses for, you know, running that combination, so running maximum cross-chaining. So it may be that you're going to be better off running, say, a 32-tooth chain ring, which may enable you then to, you know, remain much more time in your second largest cog as opposed to your largest cog. You're going to have overall lower losses by running that combination as opposed to running a more extreme cross-chain for a lot of the time. So, for instance, running a 30-tooth or 42-tooth, you know, if you're doing an hour or two of climbing in a massive event, like, say, Leadville, that's going to quite likely work out much better than pushing it to the extreme and running like a 30-tooth or 52-tooth. So most times, larger is going to be lower friction, but then maybe cases were going smaller and having a lesser extreme chain line is going to actually work out in your favor. Interesting. Okay. And thoughts on ceramic bearings. That was the last component of that question. Yeah. So, I mean, it's one of these things where cheap ceramic bearings are going to be definitely worse than high-quality steel. High-quality ceramic bearings, you know, yes, they're clearly going to be an upgrade. This is where you've got to kind of tend to think of your bike really as like a race machine. So your fastest ceramic bearings typically are going to be faster, not only by being, you know, sort of a high-quality ceramic, but they will have a lighter, you know, faster grease with a lower fill level and typically very light or no contact seals. So they do need more care and maintenance in general than your sort of OEM, say, Enduro AVEC-5 or AVEC-3 bearing. So faster, yes, but you need to maintain them. A lot of ceramic bearings, if you don't maintain them. So that lighter, faster grease will wear down more quickly. And when the grease also wears down past a certain point, so the grease behind the seal lip forms what's called a hydro-dynamic barrier behind that seal lip. And that is actually a large part of the protection of stuff getting inside your bearing. Once it gets to a point where that barrier is no longer there, stuff gets in super easy, especially on a wet ride, it will just go straight in. So just take note that for almost all fast ceramic bearing upgrades, you do need to maintain them. And if you don't, if you let the lubrication, they will become quite low. Quite often, basically the ceramic balls will become almost like carbide cutters to the metal racer, the bearing. So you can destroy the metal racers quite quickly. And this is where your really high quality stuff, where they have very, very hardened racers, they will stand up to punishment much, much greater than your cheaper stuff that just has sort of your more stock standard, you know, steel racers. So, yeah, so yes, but with some caution. And so somebody's weighing out, you know, the cost and the maintenance and all of this, you've given out some figures on how many wide savings, certain lubricants and chains are. What kind of wide savings are we talking about by giving bottom bracket upgrade, for example? Yeah, generally not that much. So it can, it can depend. So some bottom brackets, only bottom brackets can be fairly draggy, but they're draggy, not because the bearing isn't necessarily super slow. It's just because they've got, you know, like double lip height, you know, higher contact seals and they're packed full of a longer lasting grease. So an example would be like, for instance, a Durace bottom bracket. They're really sort of made by Shimano to give somebody 20,000 or 30,000 kilometers of, you know, road kilometers of service-free, trouble-free riding. But you're paying for that in drag. It's a bit like this is a passenger car bearing that's designed to go 300,000 kilometers in a passenger car, trouble-free, as opposed to a bearing that you're gonna have on your race car that's gonna get a lot more attention and be much lower friction. So you can save say half a watt straight up by going to a bearing upgrade. And a lot of those going to literally be because they have a light or no contact seal and fast grease. But the cost of that is maintenance. So, but most bottom brackets, if you're, like a slow bottom bracket is going to be somewhere around a watt-ish and a fast bottom bracket is going to be somewhere around the 0.3 to 0.5 watt mark. So you could sort of call it half a watt to a watt max that you would save if you took a sort of worst case bottom bracket scenario and this is sort of talking new versus a fast. Things could obviously be more if the bottom bracket is not performing well. If your bottom bracket sort of gone to crap, then yeah, you've got more to have on there. Carries on, so wheel bearings, it's similar like this. If you said on average, there's gonna be about a half a watt max saving per bearing by going from stock OEM, ABEC three steel to a high quality ceramic, then you can carry that across most of the range across your bike. Caviets to that, pulley wheels tend to be, although yes, you can get to see a pulley wheel on YouTube that spins forever versus an OEM that's gonna not spin at all. Just remember that it's such a light object that there's typically in the bearings on a pulley wheel, it's not much savings there in the bearings you're talking probably point one of a watt difference between a fast bearing and an OEM. So most of the savings will be in like your oversized pulley wheel systems which are a bit more expensive. I like them, but, and I guess the maths and physics do back that yes, they will save you some watts. Basically all of the savings are really coming from the lesser articulation around the pulley wheels as opposed to the faster bearings. So yes, the faster bearings help, but again, you're only saving like about point one of a watt in the pulley bearings. But this is one of these areas where again your, I guess the marketing for a lot of oversized pulley wheel systems often claim that there's like two, two and a half watts savings. That's really going to depend on what chain did they test that on? If you've got a four watt or three watt wax chain, you are not going to save two and a half watts of that in your oversized pulley wheel system. Similar thing where if you've got a really fast chain, your penalty for things like cross-chaining and so on are less, the savings for something like an oversized pulley wheel system on a really fast chain are going to be lesser as well. I like them mostly because it's a fun bling upgrade that still saves you something. So anytime I can put something cool on my bike that is still an actual performance benefit, I tend to try to go for it, but it depends on your budget. So thanks for watching. I left the link to zero friction cycling down in the description below if you want to check it out. If you enjoyed this video, be sure to give it a like, subscribe and share it with your cycling friends. See you in the next one.