In just 4 hours, Sam Calder, the founder of Rule 28, chopped 13 minutes off Dylan Johnson's Unbound estimated finish time. 13 minutes. But the craziest part, the biggest gain didn't come from a new frame or a $3,000 wheel set. It came from something that cost less than your morning coffee. When Sam took Dylan into the tunnel, they discovered something that flips the script on what we thought we knew about going fast in gravel racing. Because if you're leaving even five watts on the table, you're handing your rivals a fiveminute head start at your next race. Today I'm sitting down with Sam to unpack the most surprising findings from that test. Aero tradeoffs, hidden mistakes, and the gear choices that make the biggest difference. Welcome to the Roadman podcast. Sam Calder. Sam, welcome to the Roadman podcast. Thanks for having me. You had Dylan Johnson in the wind tunnel and we're all very curious as to exactly what happened, what the gains were, what the testing protocols were, and I think importantly for a lot of listeners, where's the easy gains that they can apply into their own racing or possibly training if you're looking to half wheel and smash one of your training partners. Maybe to start out, when Dylan came into the wind tunnel, did you have a testing protocol in mind? Yeah. So for for Dylan, he's been to wind tunnels not with us but separately um quite a few times before. So he does know what he's doing there. I think he was quite impressed with Silverstone just sort of the extra features that it has that none of the tunnels he's been in before did have. Um things like uh cameras on the side, top and front and then they will project your images in front of you. So you can see exactly the position that you're holding and compare that to a previous one. Seems pretty um common sense to have something like that so that you can make sure you're keeping a constant position, but none of the tunnels in the US had that. Um so yeah, it's it's a very good tunnel uh to go to and use and it allows us to to get really accurate precise data. So for for Dylan when we took him the main thing we were looking at was validation of some of the work we' done before and then a few different optimizations for him for the 2025 season. So main thing we were excited to show him was the the different fabrics that we've been working on uh where we could upgrade his suit and then really helping him with some other things like helmet choice as well. Um, yeah, just to make him an all round fast athlete. Kit is one part, but yeah, we're we're here to help him with everything. When I'm getting packed for a bike race, when I'm packing my bag, I always think about in my head, okay, I'm getting dressed. I'm getting dressed from the ground up. So, let me think about that in terms of the wind tunnel testing. So, if we're getting dressed from the ground up, first thing Dylan's likely putting on is socks. I know you have the new one sock. Did you test old socks versus new socks? If so, what were the results? Yeah, we tested with him old versus new. We also tested our Neo socks, which is a dual layer sock like our skin suits. Um, that one didn't actually work on him, which wasn't really a surprise because it's aimed at sort of 50k an hour plus as a speed range. Um, more of a track. Yeah. Uh, so different way it works. Um, different demands for 50k an hour versus 35. So, wasn't really a surprise, but we figured we'd give it a go, too. Uh, we tested him with the new one socks, our older version of socks, and our aero-ish socks. Um, which are more of a training sock with a bit of added flare. They'll save you a little bit, but um they actually do still perform quite well at low speeds just because it's a a different way it works um versus what you need at mid and high speed. But yeah, it was a a good gain on Dylan. So his his race speed of 35k an hour, I think we had about a 3 watt performance gain versus our previous generation of Aeros. That's amazing. Yeah. And did you test that at various speed ranges? So say 25k an hour, 30k an hour, 35, 40k an hour. Yeah. So for Dylan, we weren't really interested in anything above 35k an hour. So we did 25 through 35. 35 being pretty spot on for what the the front of the pack will be at for Unbound. Um so it's a really good option to optimize him around. And as you say, you tested your newer 50k an hour track socks. What are they called? Uh Neo. So Neo needed the the previous uh season, the error base layer that we had needs to be worn with a a smooth skin suit.
So we called that one the Neo suit being it's our new suit. Um so as it was a standalone product, it was called that. We then expanded it into a range of products. So we had a road version, a tri version, and then the socks and over shoes as well. Got that sort of dual layer upgrade. So it went into calling the whole thing Neo, which then matrix wise also helps name the single layer suits uh and socks. We called them the one. Uh so yeah, it's I'm looking forward to the full Morpheus launch in four years from now. In terms of the in terms of the fabrics, what's the different how do the different fabric choices from your old sock to the new one to the neo sock, how do they influence speed, airflow, like what's the considerations when you're thinking of these new fabrics on what new fabrics to test? Yeah. So, the the biggest difference we made between these two is we swapped from a a knitted fabric that we' used previously, we're now using woven fabrics. Um, it gives you much more precision in terms of the construction of the fabric. We won't go into it too nerdly because I don't think anybody will care particularly that much, but the uh the fibers you can use are much finer. You can pack them much closer together, so you can get much better performance out of them. Um, for the the textured fabrics that you're seeing on the one socks as well, the the way they work is kind of inverted too. So older generations, the ribbing was actually a a thinner part of the fabric. So you had the small lines would be actually a step down in the fabric. The newer fabric, that area of the thin rib is actually thicker, so it steps up. Um, small won't really mean anything to people, but it's a different way that it then works to turbulate the air flow. Um, and we found a a good gain from doing that. And when you go to the dual layer, you're saying that works at speeds over 50k an hour. Why is that? Why is that not working at lower speeds? It's it's a tricky one on the legs because it works on arms of suits higher than that. So, it's it's a bit of a weird one that we don't have a good answer to on the socks as to why it doesn't work at a lower speed. On the the suits, the way it performs is kind of like a smart material. Um, so you've got fabric draped over a structure underneath. Um, then in areas of high pressure like the front of the arm, that top layer of fabric is pushed down more into the under structure. So you get more texture in those areas effectively. And then in areas of low pressure where you don't want any structure, that fabric is pulled away from the ribbing underneath slightly. So it ends up being smoother overall. So with changes in your and things like that, you actually get to control effectively where texture is on the arm. So yeah, it's it's quite a clever way of doing things. I found your whole testing session just really interesting because you tested kind of quirky stuff that I typically I've been in the wind tunnel once a good few years back and it was for a track and we didn't get to play around with all the cool stuff you were testing for gravel. Like you tested the reservoir down the back, you tested sunglasses on the helmet, no sunglasses, and sunglasses down the front. And unsurprisingly for anyone who's, you know, slightly follows the arrow scene, if you can close that gap in between your two pecs by putting the sunglasses or a bottle or anything in there, even stuffing your gile down the front of it, as I did for my TT last night, it seems to be faster. when you went to testing the reservoir, why not build the reservoir into the front to close that gap off? Um, it's a tricky one. It's it's mainly comes down to comfort there. Um, having something on your front is a lot more obvious uh in terms of feeling and comfort uh than on your back. Um, there we do have an option to do that. So, we make a cargo base layer if you want to put a bottle down your front, but as it's designed for for gravel races, having a a three kilo pack of water on your back is quite a bit more comfortable than having it pulling on your front. Um, in terms of space as well, it's it's just about making a rider comfortable. Like the the whole thing people usually think about is um what's per kilo. The thing we think about here is what's per CDA. So if you can get your drag down for the same power, great. But if you're then doing something that's going to impact your power, that's going to throw off the numbers.
And it anyone who's ridden a gravel race and you're in the wheel at 35k an hour, your visibility on hitting a paw hole is practically zero. You're reacting in milliseconds. So you are absolutely nailing these holes and having that 2.2 I don't know statistically how much it reduces your puncture chance but it definitely helps. Yeah. And I think there's there's different levels to puncture protection and things like this that you then have to factor into it. So are you are you willing to save a watt or two for having much less puncture protection and then kick yourself if you do flat and that's the end of the race. Um, so it's it's not as simple as just going this is the fastest on paper. I'm going to erase that every time. Um, yeah, it you can go down the rabbit hole of trying to figure out all the different inputs that you need to figure out your decision. Since you started rule 28, you've spent a lot of time in the wind tunnel chest testing fabrics, optimizing this clothing to be some of the fastest in the world. Did you have a moment where you looked at a test run data and you just thought, "Whoa, this changes everything." Probably like, yeah, this this upgrade in fabrics that we just made. Um, you you can't tell by looking at a fabric how it's going to perform. Um, but you can over the years get a a rough idea of sort of what you think's going to work and what's not going to work. So once we had these made, you're going like, okay, there's a there's a good chance this is going to perform quite nicely, but it's it comes down to seeing in the tunnel and yeah, seeing that readout and just going like, okay, this this is a massive improvement on what we could do before cost a lot to do in terms of to produce these fabrics, but the fact that we don't care about anything else besides performance as a brand, like it's not it's not cafe kit basically. Um, so once we we found the performance, we couldn't really say like, yeah, but it's going to it's going to make quite expensive kit, it's like, yeah, for good reason. Um, yeah. So, yeah, that that does change quite a lot, I think, in just what we can offer to people. What's coming down the pipeline? Have you anything in the secret vaults that you're working on that's not quite ready or even where the aero industry is going? really think have we you know obviously that parto principle uh 8020 it seems like we've made a lot of the easy gains already is it now a case where we start chasing marginal within marginal gains um I think I think the main thing to look at is customization um as everything is really specific to fit and like your body proportions Um, we don't offer custom fit at the moment, but I get quite a lot of people getting into contact saying, "Hey, look, I'm quite tall, but quite skinny. What's the best size for me?" And typically, people in the past would have gone like, "Go for the tightest thing you can get into because it will look good." Um, and tight is right unless you have a good Yeah. I tend to lean the other way and go like, "Hey, look, if you're if you're 190 cmters, get the XL and take the suit to a Taylor's really stand there in it and get them to take out any of the excess material." Um, because yeah, we could customize kit, but it's going to cost you a lot more than just getting something off the shelf from us and getting it made to measure on you. It's going to be much more accurate you doing it yourself because you'll be there in person. But yeah, I I would push people that way if they're looking for the next step. It's it's fitting things to you personally. Brilliant. I love it, Sam. There's some brilliant insights. Thank you for being so open with sharing all your wind tunnel data and really appreciate you taking the time to chat. Oh, thanks for having me. Great to talk. Thanks for watching Roadman. Take one second. Click up here to subscribe to the channel and click down here where there's another video I know you'll love. See you next day.