 Whether you like it or not, and whether you asked for it or not, aero gravel bikes are coming. Now, for sure, there are some people watching this right now that are rolling their eyes. I mean, do we really need aero gravel bikes? Sounds like the bike industry just trying to get more money out of us, just like they did with disc brakes or electronic shifting or chamois that are made from some material other than wool. Personally, this is exactly what I've been waiting for, and I'll explain why, as well as giving you a rundown of my personal aero gravel bike, which is Factor's new OSTRO gravel. So first things first, why the hell should we care about aerodynamics when we're riding gravel? Aren't the speeds so low that it doesn't even really matter? Well, it's important to note that aerodynamics makes some sort of small difference at all speeds, even very slow ones. But as your speed increases, it matters exponentially more. I want to demonstrate this quickly by playing around with bike calculator, and this should give you some sort of idea as to how much aerodynamics matters at low speeds. These are, of course, just rough estimates, and the actual time saved varies based on a whole host of different factors. But again, this is just a demonstration. So let's say that we've got 100 kilometer or 62 mile gravel course, which is a pretty standard distance for a shorter gravel race. Let's look at the difference in time to complete the course in the hoods, and then in the more aerodynamic drops position. The speed that I choose will be for the hoods, and then we'll see how much faster we go when we move to the drops. Starting with 15 kilometers per hour or 10 miles per hour would save you around 25 minutes. Going up to 25 kilometers per hour would save you about 18 minutes. And if we go up to 35 kilometers per hour, we are saving about 13 minutes. Wait a minute. Why are we saving more time at lower speeds? I thought aerodynamics mattered more at higher speeds. Well, it does, but at slower speeds you're out riding the course for a longer period of time, and hence you're out in the wind for a longer period of time. Keep in mind that at 15 kilometers per hour, moving to the drops only gained us about one kilometer per hour, while at 35 kilometers per hour going to the drops gained us about three kilometers per hour. But when you're out on the course for so long, that extra one kilometer per hour adds up over time. Dude, if this entire video is just going to be you playing with your calculator, then I think I'd rather watch GCN. Yes, aerodynamics matters more at higher speeds, but that doesn't mean that it doesn't matter at all at lower speeds. 15 kilometers per hour is so slow that most people can't even feel any air resistance and would probably never think to use the drops. Now, there is a point to be made that when you're actually riding at this speed, like up a steep climb, you could potentially put out more power if you stick in the hood's position. But the point is still that aerodynamics matters even at this low speed, even if it doesn't feel like it. And if there's a point that I hope that I've driven home multiple times on this channel, it's that you can't necessarily trust your feelings. Let's get back on track here. We're talking about aero gravel bikes. Now, going from the hood's position to the drops position is likely more of an aerodynamic benefit than you'll ever get from your bike, but that doesn't mean there aren't some real gains to be had by optimizing your equipment for aerodynamics, even on gravel. Let's go ahead and get into my personal equipment choices to maximize aerodynamics for gravel racing. Aero gravel bikes are far from the norm right now. There are really only a few companies that make any sort of aero claims in regards to their gravel bike. One company that is on the forefront of this, however, is Factor, and I've been lucky enough to work with Factor this year and been able to race and give feedback on their new Aero gravel bike. For those familiar with Factor's lineup, you'll probably be familiar with the Aero, which is their all around road bike with emphasis on being both lightweight and aerodynamic. The Aero gravel looks very similar to the Aero with the most notable difference being the wider tire clearance. In fact, this summer when I was posting pictures of the bike when it was still a prototype, people were asking me how I fit such wide tires into my Ostrow. I would have asked why you always choose a white kit when you ride in the mud, but to each their own, I guess. While we're on that topic, let's talk about tire clearance and what tires I generally run for gravel racing. The Ostrow gravel has clearance for up to 45 millimeter tires. If 45 millimeters seems like overkill to you, what I will say is that I have personally tested wider tires on gravel and generally the wider the tire, the lower the rolling resistance seems to be. Renee Hurst has done some work on this and found that there was no difference between a 28 and 44 millimeter wide tire and this was on smooth pavement. And if there isn't any difference on smooth pavement, that means almost certainly wider tires have a lower rolling resistance when we get on to rough gravel. I've even gone as far as to test 2.2 mountain bike tires versus gravel tires on gravel and there doesn't seem to be any discernible difference and if anything, the mountain bike tires roll a little bit faster. So why aren't we seeing gravel pros running these massive 50 millimeter or wider tires when they race? Well, first, I'd like to reiterate a point that I've made many times on this channel. Just because someone fast does something one way does not mean that that is the fastest way to do it. A perfect example of this is how pro road racers and all roadies for that matter were on 23 millimeter tires pumped up to 120 psi 15 years ago and now they're on 25 millimeter to 28 millimeter tires pumped up to 70 psi. Whenever a pro wins a bike race on a certain bike setup, people resort to, well, clearly it works for them and I guess that's true in the sense that they were able to cross the finish line first on the bike that they were riding but that doesn't mean that it was the fastest bike. 15 years ago, Rockhard skinny tires didn't work for the pros. They just simply went slower and now they know better and they go faster as a result. Sure, but my uncle's best friend has a sister whose dog chased after this really fast pro roadie who read on a fortune cookie that 23s pumped up to 120 psi are actually the fastest. So there you go, man. I mean, the proof is in the pudding with my tire width rant over. There is actually a good reason that actually has to do with performance for not going overboard with the tire with even on gravel and that is aerodynamics. Wider tires are without a doubt less aerodynamic and this is both because wider tires take up a greater area and because they make aerodynamic shaped rims less effective. In fact, there's a point at which a tire gets wide enough that the aerodynamic profile of a rim has almost no benefit. Many gravel tires approach this point, but it's hard to say exactly where this point is because it really depends on your tire and rim combination. So it's hard to make a blanket statement like at this certain tire with your rim aerodynamics no longer matters. What this means for tire selection is that choosing the fastest tire is a balancing act between aerodynamics and rolling resistance. And where that sweet spot lies is course dependent. For example, on a rougher course, the improved rolling resistance that you get from a wider tire may outweigh the aerodynamic benefits that you get from a narrower tire, both because the speeds are lower and because a wider tire rolls faster over that rougher terrain. On smoother gravel, the speeds get a bit higher and you don't need as wide a tire so you can get away with the narrower, more aerodynamic option. So what tire do I personally choose to run? Well, most of the time I'm on the 42 millimeter specialized Pathfinder Pro. I've just found that this tire is a good mix of fast rolling, good puncture protection aerodynamics and from a handling perspective, 42 millimeters is a pretty good size for most gravel courses. That being said, depending on the course, I will sometimes play around with other options and I've gone as wide as 45 millimeters on the Ostro gravel and there is room to spare even with the relatively wide 25 millimeter internal rim width on the Black Ink 34 hookless rims. Now let's talk about one of the most exciting features of this bike or at least the feature that I'm the most excited about and that is the handlebars which have the option of running integrated aero bars. I know, I know we're getting into some controversial territory here talking about aero bars on a gravel bike video but in my honest opinion, I think that these aero bar haters are falling victim to a fairly common condition known as conformity. The reason I say this is because the decision to use aero bars at a race like Unbound for example where they're both legal to use and a massive advantage is so obvious that an 8 year old could make the right choice and yet we have gravel pros pontificating about the spirit of gravel being broken and trying to peer pressure riders into taking them off their bike. I won't be peer pressured though. If they're an advantage and they're not against the rules, they're on my bike. It's as simple as that. Hey, looks like you actually watched my spirit of gravel video. Rule number 13, when it comes to aero bars, be sure to pick a side and be a dick about it. Nice work. That being said, please don't be one of these people who throws TT bars on your bike the day before the race. You're not going to be used to them, your back is going to hurt and you're going to have a bad time. Not to mention, you're not even going to be able to utilize them to their full potential. If you're going to use TT bars in a gravel race, then be sure to train and practice with them first. Factor was willing to listen to the ramblings of me and other gravel racers who wanted a clean aero bar solution for these races like Unbound and in my opinion came up with the best aero bar setup for a gravel bike that's currently available on the market. The integrated bar stem combo from Blackank, which is already an aerodynamic profile instead of a round bar that you see on so many gravel bikes, has two bolt holes in the top of the bar to mount the same aero extensions that Factor uses on their Hanzo TT bike. The extensions have plenty of adjustability so that you can dial in your position and are easily removable for when you pop into a gravel race that either doesn't allow aero bars or where aero bars may not be an advantage. Also, the brake hoses and DI2 cables are fully internally routed through the bar and frame. I know that bike mechanics watching this are probably shaking their head right now, but there is a reason beyond aesthetics to internally route everything. And yes, that reason is aerodynamics. Obviously, it depends on how much cable you have exposed, but a nest of cables on the front of your bike can create a surprising amount of aero drag. Hidden cables have obviously caught on in the aero road bike market but are far less common in gravel bikes right now, but I bet that will change in the near future as aerodynamics becomes more and more of a priority for performance gravel bikes. And the aero details of this bike don't stop at the handlebar. You can find aero optimized shapes on the fork, head tube, seat post, seat tube, and down tube as well. I'd also like to get into the drivetrain of this bike because there's some things that I've done to optimize efficiency. I don't have a partnership with either SRAM or Shimano, which means that I could run either. The reason I've gone for Shimano GRX is because the Shimano Dura-Ace chain has been shown to be the most efficient chain on the market in independent testing, saving a couple of watts over a SRAM chain. I also opt for two front chain rings instead of a 1x for that same reason. Because with a 1x drivetrain you have to cross chain more and because the chain ring is smaller, meaning the chain has to articulate more, a 1x drivetrain is generally less efficient. On top of this, a 2x keeps the jump between gears smaller and you can get a very wide range without having to run a massive mountain bike cassette. I also run larger chain rings than you might typically see on a gravel bike with a 52 big and 36 small ring. This isn't necessarily because I need the 5211, but more so because larger chain rings, as I just said, are more efficient that they allow you to ride more in the middle of the cassette and use those larger cogs, which again are more efficient than the smaller cogs. In the back I've got an 11-34 tooth cassette and ceramic speed oversized pulley wheels to further improve efficiency. And on race day I will generally hot melt wax my chain and hopefully you're noticing a pattern at this point. This is to further improve efficiency of the drivetrain as well. All these little drivetrain changes are all very marginal gains by themselves. But when you add them all up and compare them to a setup that makes all the wrong choices, you could be looking at 10-15 watts of savings. And no, that's not me trying to sell you something, that's what independent testing shows. The bike as built up here comes in right at 19 pounds or 8.5 kilos, which is pretty lightweight for a gravel bike and I'm certainly happy about that. But weight is actually probably my last concern when it comes to these marginal gains and that's because of the marginal gains that you could potentially make, weight is probably the most marginal. That's right, if you were to rank aerodynamics, tire rolling resistance, drivetrain efficiency and weight in terms of how much time you could save by optimizing for each, weight would actually rank last for the vast majority of courses unless we're talking about a race with some serious climbing. Yeah, but what about impressing your riding buddies when we're all standing around in the parking lot after a ride and picking up each other's bikes for some reason? If all this mumbo jumbo about aero and efficiency seems like I'm overthinking it and I should just chill bro and ride my bike or whatever, I'd like to take you back to this year's Unbound 200 where I broke 10 hours by less than 2 minutes, a feat that up until this year had only been done once. If just one of these optimized features had been changed out for something less optimal, then over the course of a 200 mile race that could have easily been the difference that put me over 10 hours. If we switch out all of these optimized features for something less optimal, then we're probably looking at 20 to 30 minutes slower and many lost places. Well, you could have just pedaled harder. Gravel is for everyone and obviously not everyone cares about how fast they go. And if that's you, then honestly, I'm surprised that you made it this far into the video. But if you do care about performance on your gravel bike, then you need to be thinking about aerodynamics and how to optimize your bike to be more aero. Thanks for watching. If you like the work I do and you want to help support the channel, then consider supporting me on Patreon and getting access to weekly members only Q&As. If you want to step up your training, then check the links below for information on coaching and training plans as well. And finally, if you enjoyed this video, be sure to give it a like, subscribe and share this video with your cycling friends. I'll see you in the next one.