AJA #44: Hookless Controversy, Tire Myths, & Aero Hacks

Summary:

Josh Poertner addresses the fallout from his viral “hookless is a scam” comment, clarifies the real risks and physics behind hookless road rims, and digs into how gauges behave at altitude (PSIG vs PSIA), why analog can be more trustworthy than digital, what pressures calculators really assume, and whether you should run a rear disc and how deep to go up front. The crew also takes questions on low-hysteresis comfort materials (bar tape vs insoles/hoods), DIY turbulator strips, and a chain-mounted power meter idea.

Presented by: SILCA — makers of the very best floor pumps, frame pumps, shock pumps, electric pumps, drip waxes, endurance waxes, speed waxes, wax melters, StripChips, aero socks, tire sealants, and more. www.SILCA.cc

Also supported by: Shimano — explore the new wireless Di2 MTB upgrade options at bike.shimano.com.

Episode Links:

SILCA Microfiber Towels — 12-pack for $20 (host favorite). https://silca.cc/collections/clean/products/pro-microfiber-towel-grey

SILCA Tire Pressure Calculator (measure actual casing width) https://silca.cc/pages/pro-tire-pressure-calculator

AJA archive (prior hookless discussions): 
AJA #29 - https://silca.cc/blogs/marginalgains/aja-29-hot-wax-on-a-hot-day
AJA #35 - https://silca.cc/blogs/marginalgains/aja-35-hookless-rims-psi-limits-tire-pressure-on-worn-tires-ti-quicklinks-crr-on-wet-roads
AJA #43 - https://silca.cc/blogs/marginalgains/aja-43-crr-cda-hookless-the-magnus-effect

Marginal Gains Hotline: 317-343-4506 (call or text)

Comment on the episode: marginalgainspodcast.cc

Credits
Hosts: Fatty, Hottie, & Josh Poertner (SILCA CEO)
Producer: Marginal Gains

Timeline:

00:03 – Sponsor Shoutouts & Microfiber Towels

• Fatty praises Silca’s Pro microfiber towels for bikes, lenses, and even hair.

• Hottie shares his own towel obsession.

• Shimano’s new wireless MTB Di2 upgrade kits get the spotlight.

03:11 – Intro & The Hookless Firestorm

• Josh reflects on the fallout from his “hookless is a scam” comment.

• Media frenzy: BikeRadar, Escape Collective, Velo, and more pick it up.

• Industry response: shops and consumers largely supportive, manufacturers less so.

08:58 – Listener Question: Hooked vs. Hookless Tire Pressures

• Why tire sidewall PSI ratings don’t match hookless realities.

• Consumer confusion when OEM bikes ship with hookless rims but “hooked” tire markings.

• Pressure calculators: why some show lower pressures on hookless and why Silca’s doesn’t.

• How tire width, rim bead width, and standards impact performance and safety.

20:54 – Standards, Safety, and Industry Tension

• ETRTO/ISO standards vs. the desire for innovation.

• Legal risks and lawsuits drive demand for standards.

• WorldTour blowoffs force revisions to the rulebook.

• Hooked rims still allow for more flexibility, innovation, and aero optimization.

31:26 – Air Pressure at Altitude

• Hottie’s Leadville Lexus TPMS story sparks a technical deep dive.

• Josh explains PSIA vs. PSIG, why digital gauges drift, and why analog gauges often outperform at elevation.

• Impact for racers: why “30 PSI” isn’t always the same depending on your gauge.

43:47 – Listener Product Suggestions

• Could Silca’s foam tech improve shoe insoles, hoods, or saddles?

• Josh explains why rigid insoles work best for cycling, but saddles might be an opportunity.

• Aero trip strips: adhesive zigzag decals from the aircraft world, tested in wind tunnels. Fun but limited gains vs. shaping.

48:58 – Disc vs. Deep Front Wheels

• Listener asks: disc rear or deep front for time trials?

• Josh explains why rear discs always win: aero efficiency, watt savings, and stability.

• The “charity wine pull” analogy: discs can deliver outsized aero gains in the right conditions.

54:29 – Chain-Mounted Power Meter Kickstarter

• Josh reacts to a quirky new gadget that clips onto the chain.

• Comparisons to Polar’s failed early 2000s attempt.

• Likely noisy, questionable accuracy, but certainly inventive.

58:21 – Wrap-Up & Listener Involvement

• Call or text the Marginal Gains Hotline: 317-343-4506.

• Leave comments at MarginalGainsPodcast.cc.

Read this Episode's Transcript

Fatty:
The Marginal Gains podcast is presented by Silca, makers of the ver y best floor pumps, frame pumps, shock pumps, electric pumps, drip waxes, endurance waxes, speed waxes, wax melters, strip chips, aero socks,

Fatty:
tire sealants, and much, much more. None of which I am going to talk about right now because I want to talk about the Humble Pro microfiber towels, which I use in a multitude of ways every single damn day of my life. I wash my bike with these, clean my chain, wash the sweat off my Oakley lenses, clean my computer screens. I am not kidding. A ton more. My wife dries her hair with these. And I would, too, if I had any hair. A 12-pack of these is 20 bucks. They are like Shamwows, but better. They don't fall apart. Josh, this is an AJA episode of the show, so I'm going to ask, why aren't these at the very top of the Silca.cc homepage?

Josh:
I think because I didn't realize they elicit such passion and excitement. Maybe we've totally been missing out all along.

Fatty:
I think you have. Hottie, in between waxing anything and everything in your vision, have you ever tried the microfiber towel silica cells?

Hottie:
Try it. I've got them spread out all over the place here at Hottie headquarters. You should see my garage. You can see them like hanging everywhere. I've got some segregated for like wiping down bikes or using the silica wax treatments, you know, the frame wax treatments. I got other ones I use to wipe my chains down with. I got them sitting in my car. I keep one right off screen here just in case I need to wipe some. So like you, yeah, I've got them. I do not wipe, you know, I don't dry my hair with them. I don't use them as a facial towel, but, you know, pretty close otherwise.

Fatty:
They actually make a great hair drying tool or face cleaning tool. I am, obviously, Hottie and I are a fan. Josh, you need to get on it. Seriously, go wash your bike, your glasses, your hair, your chain, your computer screen. Use these towels. Recommend a different towel for each task. Don't dry your hair with the same

Fatty:
one you cleaned the chain with. Pro tip right there. Go to silica.cc. I'm Fattie. Welcome to the show.

Hottie:
And I'm Hottie. This show also supported by Shimano. The long-awaited DI2 mountain bike update is finally here. We know many mountain bikes and mountain bikers have been waiting for the new Shimano electric group for years. Shimano knows that too. Shimano also knows that in the interim, many riders kitted their bikes with the highly reliable and great performing 12-speed mechanical groups. Well, if you love your brakes, cranks, and cassette and simply want the new wireless shifting, Shimano can do that in the form of an upgrade kit. In all levels of its mountain bike wireless Di2, that's XDR, XG, and Dior. Shimano is offering a package that includes the new derailleur, shifter, battery charger, and a quick link. It's a more economical way to make the jump to 12-speed Di2 wireless in mountain bikes. And by the way, if you love your mechanical shifting but want the new XTR or XT brakes, Shimano has an upgrade kit for that too. Check out all the ways to get into the latest Shimano mountain bike products

Hottie:
by going to bike.shimano.com.

Fatty:
This is Ask Josh Anything number 44. Questions provided by listeners. Answers from Silca CEO Josh Portner. What the answer is, nobody knows. Just occasionally, while I'm away from the show and you two just go off the rails, that exchange can wind up being something the media latches onto. Josh, you said during the most recent AJA that your inbox would be like flooded due to one answer you gave. So how are those replies coming?

Josh:
Oh, man. Good Lord. I really couldn't believe it. So, obviously, referring to the hookless is a scam comment that I made, which if you work here and you know me, like I have a lot of things I jokingly but half seriously will call a scam.

Josh:
Like the dentist. You know, like I hate the dentist. I'm like, that's a scam. You don't need to do that every six. Like, that's ridiculous. I didn't go to the dentist for like five years once. And I went in and they're like, oh, this looks great. Who have you been seeing? Like, nobody.

Fatty:
My toothbrush.

Josh:
I just brushed my teeth like, you know, anyway. But yeah, so I mean, I think that word triggered something. But yeah, I think we're up to like a dozen YouTube videos and podcasts from Bike Radar, Bike Rumor, Escape Collective, Velo. I mean, there's like so many of them. I mean, if you go to go to YouTube and type in hookless scam, you get like 10 or 12 videos from other people just reporting on what I said, which is weird. Like, I try to watch some of these and like, well, Josh said this. Yeah, there's like a big LinkedIn thread with a bunch of people chiming in. Oh, my God. I had so many industry people in my inbox not happy. Actually, I had a number of industry people happy. A lot of bike shop owners, mechanics, consumers through the sales at Silca.cc company inbox that I would say 99.9% positive.

Josh:
But yeah, it's been pretty crazy. And so, yeah, I think we've put out two follow-up videos. One explaining kind of the physics of what's going on and what the issues are. But also two. Really trying to kind of explain, you know, because I think the media certainly picked it up and said, Josh said hookless is a scam. I'm like, well, I said hookless road is a problem. You know, for mountain bike, it's probably fine. For gravel, it's probably fine. You know, people don't seem to be having problems. And so we've tried to refine the answer. But yes, from the people in the industry who are angry, none of it's mattered. They are pissed. So and you know tough like i you know i'm not we're not here to please them i'm just here to kind of say what it is and quite honestly the the more you

Josh:
think about it and look at it the more.

Hottie:
Yeah the

Josh:
More i was right.

Hottie:
And this is not the first time we've we've talked you've talked about this josh and pointed out kind of the deficiencies with hookless road aja 29 we talked about it aja A35 was another time we talked about tire pressures and tire widths and whether or not a hookless bead would hold onto those tires properly. It was the first time maybe you used such a strong word, but you've been on the record a number of times on this show in particular saying that you had a problem with the technology. So it wasn't a new take by any means for the people who thought Josh was just trying to do clickbait, trying to attract attention to the podcast or no, no, no. We've, we've been talking about this for a while, the issues we've had with it. So not, not a first.

Josh:
Yeah. I would say pretty much everybody who's angry has said, uh, clickbait or inflammatory. And, and, you know, I mean, you go listen to that podcast, like it, that was so off the cuff and, and just kind of rolled out of my mouth. And I, you know, as soon as I said, I'm like, oh shit, I'm going to get people like, uh, people aren't going to be happy about that. But no, I think because I use that word... Got a lot of attention. And I think, quite frankly, there's just not a whole heck of a lot else going on. I mean, you know, Bike Radar basically did, I think, like a 17 or 18-minute video, like, just talking about that and playing clips from our podcast. You're like, oh my God, they just, they clearly had nothing better to do or talk about the day that they put that together because it, you know, I mean, I look at that, like, someone spent a few hours building that video and the b-roll and all the stuff around it we should do a.

Fatty:
Reaction video to their video about our

Josh:
Podcast we could just get into a loop we could be like dozens of videos about mirrors other videos yeah mirrors looking at other mirrors i did.

Hottie:
Make sure to grab grab the one comment i was so happy to hear my name called out in one of those videos where the the presenter said oh Michael Hottie Hotton in a very British accent. I love it. So I've got it somewhere that I'll have to drop in at some point.

Josh:
Michael Hottie Hotton.

Fatty:
I'm calling you that from now on, Michael Hottie Hotton.

Hottie:
Michael Hottie Hotton. You've got to give it the right...

Josh:
You've got to have the accent.

Fatty:
I don't have it.

Josh:
Oh, that's great.

Hottie:
Well, unfortunately, Josh, you know, the topic's not done yet. Certainly, since it started on this platform, we want to revisit it here, give you the floor to maybe clarify any of the stuff that's since come in after that show. So let's jump straight to our first, second, and third Lesterner question. All in one here. Yes, a three-parter called into the Marginal Games hotline at 317-343-4506.

Speaker3:
Hey, Jack. Steve here calling from Boston. I've got a three-part question regarding hooked versus hookless wheels. First, a key part of your argument in your recent YouTube video is that tires will blow off a hookless rim if cyclists aren't educated enough to set the pressure below the right level, say 70 PSI. Can't the same be said for hooked rims? We've been educated to set them below a specific pressure, say 120 PSI. Hookless rims have been on road wheels for at least 10 years and mountain bike wheels forever. How long do hookless rims need to be available to the cycling public before we should expect them to be educated not to inflate them above 72 PSI on road rims? Secondly, I know silica tire pressure calculator doesn't differentiate between hooked and hookless rims, but those from other reputable sources recommend pressure is 3 to 5 psi less with hookless rims than hook rims, all else being equal. Doesn't being able to ride at a lower tire pressure on hookless rims give you the benefits of lower vibrational rolling resistance, better handling, and more comfort? Or do you reject the premise of the question, and if so, why? Third part, bonus question, where do many hook rims fall in your view of safety and recommended tire pressure levels? Thanks.

Josh:
Can I just say how much I love when people call in with the question? I just love hearing it in his voice. Steve, if you want your question, want to be sure your question's answered, call it in. I think we 100% of them make it on the show because we do love that. But this is a great question. Okay, so three-parter. Let me try to make sure I'm remembering them all.

Josh:
Okay, so first part was, can the same be said for hooked rims, right? So I think the thing with hookless that we need to think about is, you know, in the hooked or the crochet rim standard, the tire, and this is, I think we said it in one of the videos, but the C, in like 700C. So you have 700C rims and then the tires that are also marked with the 700C. They have a max sidewall pressure printed on the tire, which is what people have looked at forever. And that number is based on a number at which that tire on a 700C rim can surpass at least 125% of that number. So, you know, if it says 100 PSI max, then it is guaranteed that that tire can handle at least 125 PSI on a 700C rim. So, part of the problem with the hookless is the hookless rims showed up, but there aren't hookless or what ISO and ETRTO are calling TSS, tubeless straight side.

Josh:
There's no tire standard for that. And so, the tire pressure on the sidewall is still based on the crochet hooked rim standard. So one of the biggest pieces of confusion is customers, especially with OEM bikes, like they buy the bike, they might not even realize those rims are tubeless straight side, right, hookless. But the tire still says 100 PSI max or 120 PSI max or whatever it says on the side. And so now it's on the consumer to know what the rim is, to know that, oh, the rim has a 72 PSI max because it's hookless, but the tire still says 100. So I think part of the problem is that the standard hasn't moved in sync the way that it used to be, right? 700C, that's the tire and the rim very much in sync with each other.

Josh:
Going to hookless, we've broken that and now you have a tire with pressures on the sidewall that are related to the old system and you may have a different rim. So I'd say there's a lot of confusion around that and his kind of question, you know, should we expect them to be educated not to inflate above 72 PSI? I think when we're talking about aftermarket products and kind of the, you know, old school, like, you know, like when we, started, you know, the zip wheels way back in the day, right? Nobody specced them. That was an aftermarket purchase.

Josh:
I really, I think we can educate that customer and I do expect them to know what they've got.

Josh:
But these wheels are coming on OEM bikes. And I, from my experience at events, a huge percentage of the people on some of these products have no idea that that quote unquote technology is in the product they have. I mean, you know, and we know that because they roll up and they're like, oh, can you give me 90 or 100 PSI? And like, whoa, those are hookless. Like, what do you mean? Like, oh, your rim. And then it's a whole discussion. And I would say quite often they will say things like, oh, but the tire says, right, well, you know, it's just sort of a big rabbit hole to fall into. Well, actually, that means something different for a different type of rim. So part of this is, yeah, the standard needs to catch up. You know, it would be great if the tires said both, right, for, you know, hooked rims, here's your max PSI, hook less rims, 72 PSI. Yeah. So, the next question, so a tire pressure calculator doesn't differentiate between hooked and hookless rims. The reality is that it doesn't matter that the most efficient tire pressure is the same hooked and hookless. What a lot of the calculators out there that are showing you lower pressures for hookless are generally assuming that the tire is actually inflating to a wider width on the hookless rim.

Josh:
Because there aren't the hooks holding it in at the bottom, right? And so they're leading you to a lower pressure on hookless because they're assuming that that tire is sitting somewhere in the, you know, like 0.8 to 1 millimeter wider on that rim than it would on a rim that were hooked. Because the Silke tire pressure calculator is based on the actual measured width of the tire.

Josh:
It doesn't matter if it's hooked or hookless. So, you know, as I said in one of the videos, the problem and why you need to measure the tire for tire pressure calculator is that, you know, we did a study, bicycle rolling resistance. We looked at, they measure the lay flat casing width. Like if you flatten your casing out on the table, how wide is it? And for 28, quote unquote, 28 millimeter tires as printed on the sidewall, the casing width lay flat range between 69 and 76 millimeters. So it's a 10% difference, right? A 10% difference. And part of that is that the different companies are making different assumptions when they put that sidewall width down, right? It's like, you know, some of them are saying, well, that's on a 17 millimeter inner bead width. Some are saying it's on a 19 or a 21 millimeter inner bead width, and so the tires are quite different. And so, you know, a 28 millimeter tire can actually mount and be somewhere between, you know, 27 and 30, depending on what, you know, what the rim inner bead width is. And that's why we talk a lot in one of our videos about the DD standard, and I even show the little tool, but it's basically a tool that you can wrap the tire casing around to get that, you know, what I would call like the circumferential length or same as the lay flat length if you flatten it out.

Josh:
But those can be quite different, and then you're putting it on the different, you know, internal widths of rim. So the best way to do it is just put it on, measure it, and that's going to give you the same number regardless. So, it's a great question, but the assumption being that, you know, hookless allows for lower pressure, and it doesn't. It's just that having the tire be wider allows it to run at lower pressure. So, that's unrelated to hookless. And then question three, you know, where do hooked rims fall in my view of safety and recommended tire pressure levels? Yeah.

Josh:
I think the other thing that's happened with the current kind of ETRTO change is that the old 125 percent rule has been taken to 10 percent. Partly, I think, you know, pressures are coming down in general.

Josh:
You know, those groups, the ETRTO, the ISO, they're committees and they're made up of industry people, industry insiders. And, you know, they're super well-meaning, but they also want what they want. And, you know, I think there's always this tension of, you know, we want it to be safe, but we also want it to be flexible and we want to be able to innovate, right? We don't want, you know, I look at aviation, I'm a big aviation nerd. And, you know, aviation's really hard, right? Because it's so rigid that it's really hard to innovate. And when you do innovate, it takes 20 plus years to get that innovation out there. You know, we don't want that in cycling. We want to be able to create something and actually get it to market. And so there's this tension between innovation and sort of safety from a, you know, repeatability standpoint that's out there. So, I, you know, to me, the hooked rims, I think, allow for greater flexibility, better consumer choice, and more potential innovation going forward in terms of new tire technologies or fitting, you know, one of the things I'm a huge believer of is that these pressures have come down is.

Josh:
You know, we see with hooked rims, you can still exceed the 125% blow off. With only three millimeter difference between tire width and inner bead width. So, you know, I talked before about the 3T discus wheels that have a 29 millimeter inner. You can mount a 32 millimeter GP5000 on there. It'll actually balloon out to be about 35, 35 and a half millimeters. And that thing will easily hold 100 PSI in that configuration. And of course, at that width, you know, I run mine like in the 36 PSI range. I mean, really low.

Josh:
And it's super aero, right? Because your tire is a good 35, it's still well narrower than the 40 millimeter width of that rim. So that's actually one of the most aero setups in the wind tunnel of a tire that wide. If you were to do that with hookless, you've got to have at least the 4 to 5 millimeter wider tire than the inner bead width. And so that 29 inner, you have to have at least a 34 millimeter tire by sidewall. And there were 35, and now you're not able to get nearly the aero property. So, you know, to me, I think hooked is going to allow for better future innovation while also allowing for better safety. Um, and really the only downside is you have more expensive tooling when you're designing and making your rims in the first, the first place. So there you go. Hopefully, hopefully that's the last we can say on that.

Hottie:
Yeah, Josh, I've been thinking a lot about, of course, about this topic, some of which was because my name came up, Michael Hottie Hotton. But more than that was due to the safety concerns and kind of what's happened in Tubeless Road over the years. Back when Tubeless Road first started emerging, you kind of had these two camps, right? You had the folks who stood by ETRTO and safety standards. I'm thinking about like Mavic and Shimano. Then you had the nones of the world, like the other people who wanted to innovate, and their argument was, well, we don't want to get involved with the ETRTO. We don't need their approval because we feel their standards are too old, and it's going to stifle innovation. Now it seems like we've come around a little bit, at least the wheel industry has, where they seem like they want the blessing of the ETRTO and the ISO. right? So now we seem to have more wheel makers on board. They're looking for that stamp of approval so they can kind of pass that on to customers and prove to them that they have a safe product. So my question is, how did we even get here then? If we've got a majority of the big wheel manufacturers on board that safety standards are the way to go, then how are we even here?

Josh:
Yeah. So, I mean, I think the industry has always, again, been challenged with this tension of standard or no standard, right? We don't want a standard because we want the flexibility and the freedom to innovate. But I will tell you, you know, when something fails and somebody gets hurt and they sue, people want standards to point to, you know, and I, you know, I don't even know if there have been lawsuits or anything like that. But certainly, you know, it's a risky industry, especially here in the States where, you know, we sue people over everything all the time. Yeah. You know, and it can get a little bit crazy and they will sue, you know, multiple people, right? So, I mean, I, you know, somebody does crash, you know, with a tire blow off, they're probably going after the tire maker, the wheel maker, you know, it could be the, you know, whoever wasn't taking care of the road or, you know, there's a bunch of people they can go after. And I think the reality is if, you know, you were to be sued, like in my time at Zip, I mean, we always said, nope, we had to follow ETRTO because if somebody sues you and it's, you know, this company, big company versus somebody who's injured and the attorney says, is there a standard for this? And you, yes. Did you follow it? No. You have no chance, right? You have no chance.

Josh:
And so, I think there's a great desire from the industry to have, I would say, exactly as much standardization as you want at that moment. But then not so much that you can't do the next cool thing. And that's a really hard tension.

Josh:
And it does open. You know, I think we talked about previously the, like, stands. You know, stands in the early days of tubeless, they just threw TRTO out and started doing their own thing with these weird little partial hooks and some, you know, their own dimensions and their own tolerancing schemes. And, you know, that, I mean, that really worked for them. I mean, if you're a Shimano or any of the established brands and you're like, hey, we're big and established and if we get sued, we're the big wealthy company that's going to get completely clobbered.

Josh:
You really are giving a huge advantage to the new guy who's – what do they have to lose, right? And so I think that's where the tension comes in and I think we're definitely now at a spot where –, Quite frankly, I think, too, having multiple high-profile blow-offs with these hookless rims in the world tour. And, you know, there's a couple of them that were super, super high-profile. There's many more that people know about that didn't, you know, they just didn't happen to be captured on TV or whatever, but they happened at other events. I mean, the industry knows about that. But so the industry, you know, they really want someone to a standard to kind of have their back on this. And that's where, you know, if you notice, like the ETRTO actually went and looked as I was making one of my videos this week. I had a great conversation with Dan Enfield at Slow Twitch two and a half, almost three years ago on this. And it's interesting that we were discussing the ETRTO draft standard on this, what tire fits with what rims.

Josh:
And then in the middle of that draft being looked at by the industry, you had those high-profile world tour crashes. And then the ETRTO that actually got published changed, and everything went up by a millimeter. And that's where, you know, in the original standard, it was like, oh, you could put a 28 on a 24. And now they're like, oh, no, you have to put a 29 on a 24 and a 28 can only fit on a 23. And so, you know, I think it shows the challenge, right? That, I mean, we were probably a month or two from that standard being the published standard. And, you know, it only gets changed every 10 years or so. And those two incidents made everybody go, oh, shit, you know, and they just shifted it all by a millimeter. But I think it just shows that you can't test everything in combination. And so, you know, you've got... The crochet rims, you know, hooked rims, you've got whatever, 40 years of that standard being the standard and everybody really kind of understands it. And everybody, you know, this tolerance of the rim, this width ratio between the rim and the tire, these casing widths of tire can be defined as this tire width. All of that was really, really well known, right? And proven over time. And I think because this is so relatively new.

Josh:
It just – you couldn't test everything together in the right way, right? And, you know, because you've got to think, too, it's the – you know, the tolerances were essentially cut in half, right? A rim used to be plus or minus a millimeter diameter. Now it's plus or minus 0.5 with hookless. So it's got to be a much tighter tolerance. But, you know, you have tolerances in the tire, and the tires are a little bit stretchy. So, there's a lot of question of, you know, what tool are you measuring that diameter with? How are you measuring it? At what force, right? Because you put more force on it and it suddenly looks bigger. What tolerance is allowed there? What about creep? You know, the creep is when materials sort of stretch over time as they're held under a consistent load. And, you know, that's another one. Okay, well, it might pass the blow-off test when it's new. But what happens after you've ridden it for six months or a year? Or what happens after it's been heat cycled through, you know, really hot and cold? And there's just too many things, too many variables to make it easy to really nail that standard out of the gate. And I think that's what we're living with, with hookless. I think I said in one of the YouTube videos we did, you know, I think ultimately everything ends up hookless because it is cheaper to tool and cheaper to make. And, you know, if you just look at the history of stuff.

Josh:
When a technology comes along that is cheaper to produce, cheaper to make, cheaper to tool, it tends to stay around, right? And so I think what ultimately probably happens is road tires just get wider. You know, for me, the sort of cutoff point with this hookless thing is like 34, like 34 and above on rims that are, you know, really like probably 27, 28 millimeter inner and below. Your pressures are low. You have enough kind of balloon on the tire.

Josh:
It's pretty safe. I mean, nobody's having blowoffs on tires that are 34 and above. So, it really is just still this sort of older school thinking, people running higher pressures, people wanting to run narrower tires. You know, but we're already seeing it. I mean, you can't go buy a 21 millimeter modern tire or 23 millimeter modern tire. 25s will be next to go. There's very few people making those. And so, I think, you know, 10 years from now, it's probably like you can't even buy a 28 millimeter tire anymore. And that's probably how it ultimately gets solved. But we'll see.

Hottie:
It's just surprising that a body that moves so slow and is so stuck in its ways would ever approve the technology, for road at least, the hookless. That's what I kept coming back to. I'm like, wait, how do we even hear if this group is so slow and they have such old standards and they seem to kind of stand in the way of innovation? and how even here in the first place?

Josh:
Well, but remember, it's made up of industry people. So, you know, it's not totally independent. You know, those committees are built out of, you know, eight to 12 industry people in the committee who are actually writing and creating it. And, you know, which makes sense, right? The industry is the closest to it and knows it better than anyone else. And so that's back to that tension, right? Of, you know, I've been in some of those committee meetings for different standards and, you know, ISO and some of these testing and things. And, you know, it's different people want different stuff. And, you know, there's always like a couple of people from companies that are really slow moving and stodgy and don't want anything to change. And, you know, there's usually a couple people in there who are like, you know, let's burn this thing down. And, you know, you're trying to make, yeah, make sausage from, you know, out of that. And so that's what you get. You get what you get.

Hottie:
All right. Let's move the show along. We've been on the hookless bandwagon here, I think, quite enough. We'll give it a rest and move on to some more normal discussion.

Fatty:
Air pressure.

Hottie:
Air pressure. How about air pressure? It's tire related, right? We're kind of in that arena right now.

Fatty:
And then on to wax.

Hottie:
And then on to wax. Right. But this one actually comes from Hottie's head, I'll have to say here, Fatty and Josh. trip to Leadville, right? We all know when we go to altitude, what happens to our tire pressure? It goes up. Okay. That makes sense. But why then was Mrs. Hoddy's Lexus tire pressure warning gauge coming on? The car had been serviced a few days before the trip up to Leadville. The receipt, by

Hottie:
Tires had been inflated to 35 PSI. Now, can we really trust Jiffy Lube and their equipment? Who knows? When we got to 10,000 feet, all the tires were actually reading about 30 PSI. In fact, one was a little bit lower because that's why the warning light had come on. So that brings up, of course, another question. Can we trust TPMS? That's the tire pressure monitoring system and these automobiles. Who knows? That's for the marginal gains car gang. We'll let them handle that, I suppose. But when the tires were cold in the morning at Leadville, 25 PSI, at least on the dash, midday, they'd warm up to about 29. My digital gauge, Josh, that I use on my bike, said they were at 31. So, of course, I'm terribly conflicted by all this. My head is spinning. I've got Josh in my ear saying, oh, no, this is what happens at altitude with your tire pressure. And that led me down to yet another rabbit hole where I start reading about tire pressure gauges. And of course, you have a PSIG pressure gauge and a PSIA gauge. Josh, maybe you can help explain that. I still don't have it sorted out in my mind. I do have an AJA with all of this, and that is what kind of gauge can we really trust at altitude? Is it analog? Is it digital? Or is it something calibrated for elevation? So have at it. Please put my mind at ease here about what I was seeing and experiencing.

Josh:
Oh, goodness. Yeah, so this one is interesting, and maybe somebody out there can tell me because I've never gone super down the rabbit hole, but most – so PSI A, right, is your absolute pressure, total pressure, including atmospheric. And the PSIG is the pressure relative – is the gauge measured, which is pressure relative to the surrounding atmospheric pressure. And –, So many of these TPMS systems are built around this PSIA. And maybe one of our listeners out there can tell me. I actually first had to think about this a couple of years back. We had somebody who was into like off-road, like rock crawling, you know, like the Jeeps with the big tires. And they run them at like three and four PSI and they do this stuff. And he's like, oh, when you go to altitude, you know, it should be, we want to only work in PSIA and not PSIG. And, you know, I think The more we really thought about it is, no, for what we want, it's controlling the stiffness of the tire in that environment. You really want PSIG. And so PSIA, I think of it as makes sense for aircraft altitude measurement, things like this.

Josh:
I'm trying to think of the easiest way to kind of explain it. So, these TPMS systems, though, are, you know, the problem with PSIG is that gauge has to be calibrated to something. And, you know, this is actually, when we did the Electrico Ultimate, we actually set in. When you turn it on, it thinks for about a second. You can almost, like, see it thinking. And what it's doing in that moment is it's taking a read of the current ambient pressure, and it's making that the zero. And the reason we did that is that most of these digital gauges and this is where people get themselves in trouble with digital gauges they are zeroed at the factory right and and that's like hard set so whatever the ambient air pressure and temperature on that day that the thing was made in whatever factory it was made in that becomes the zero forever um and you know the.

Josh:
That's not a great zero to have because what we're really interested in is this PSIG number, which is the air pressure in your tire relative to the environment that you're in at that moment because we're after stiffness of the tire. And, you know, it kind of makes sense. Like if, you know, the tire has 100 PSI in it and then you put it in a chamber and you start adding air pressure to that chamber and now there's, you know, 20 PSI in the chamber around, which is super extreme, right? But then the tire becomes less stiff in that environment.

Josh:
And so that's why that's important to us. So, you know, what you really want is PSIG that is zeroed locally. Well, with a TPMS in a car tire, you can't have that, right? Because it's always – the sensor is always inside the tire, always seeing the tire pressure. And so they use PSIA. And the way that you essentially get there is, you know, PSIA can be thought of as like PSIG plus one atmosphere, which is 14.7 PSI at sea level.

Josh:
But when you go to altitude, this now gets thrown off because you kind of have the same problem of our PSIG gauge that was set, you know, that was set at the factory. Like, it's assuming the outside pressure is 14.7, right? Which it no longer is. And so, that's why TPMS sensors, they don't do super well when you go to altitude. And so, I think some car brands even have little conversions, you know, like, you know, you live in Denver. You know, you can adjust it by this. And, of course, you go to Leadville, and, you know, Leadville's, well, like, twice as high as Denver. And so you're really throwing it off up there. But that's essentially kind of the difference there. And, yeah, that's where if you were to measure it with your Electrico, you actually would get the actual pressure differential difference. Between the atmosphere that it was turned on in and from the tire itself. If you measure it with most digital gauges, you're going to get the internal pressure of the tire relative to where that thing was zeroed at the factory in China or wherever.

Hottie:
That's a huge problem, Ben, especially for all Leadville racers, most of whom do not have your pump, and they're waking up in the morning and they're measuring their tire pressure and probably using a digital gauge because a lot of us run around with those things, that means their pressure's off,

Josh:
Correct? Yeah. I mean, it really certainly could be. And, you know, I know our athletes, I mean, this is one we've had some really great discussions with Keegan about this over the last couple of years. And he was one of the athletes who was working with all the Electrico prototypes that, yeah, like he did have to actually run a different pressure than he was running with his old digital gauge. But you will notice, quite interestingly, because most analog gauges use what's called a Bordon tube. So if you were to pop that thing apart, what you have in there is this, like a tube that is in a spiral, like, you know, probably spirals in on itself five or six times.

Josh:
And the Bordon tube works on, as you increase the pressure inside of that tube, it wants to straighten, right? So it's just kind of a cool mechanical effect. And as it wants to straighten, it moves. And so, you literally have like a little, like a rack gear on the very inside of the Bordon tube. And then your needle is on like a shaft running through the center and that has a pinion gear, right? And so, it's like a rack and pinion steering. And as that thing wants to stretch, it's literally just pulling the rack across the pinion and that's why the needle is moving. And so the Bordon tube is essentially like, it is great in that application because it's giving you PSIG, but always to a local zero, right? It's always giving you relative to current outside pressure.

Josh:
And so, yeah, when you're going between altitudes, like an analog gauge can actually be quite a bit better than a digital gauge in terms of the accuracy that you're going to. So, yes. So, you know, we always tell our athletes and, you know, anyone else like, you know, hey, just, you know, figure out what works and go with it. But yeah, it is 30 PSI is not always 30 PSI, depending on what the gauge is. And I do think that's one of the real challenges with, you know, we got a lot of shit from people. You know, why do we do an analog gauge on our shock pump instead of a digital one? And, you know, there's a bunch of challenges with digital gauges.

Josh:
But one of the problems is the digital gauge gives off an air of like such... Perfection right you know people who are like oh i run it at exactly 280 and like well the problem is you know and you tell me what what brand and model like that's a plus minus five percent digital gauge so the problem is it you know you you look at the analog gauge and go oh well it's it's probably within you know one or two psi of this uh of of the 280 that's not good enough, I need it to be exactly 280. Like, yeah, but it could be plus or minus 5% of that. It's just kind of tricking you into thinking it's exactly what it is. And that's before you even get into these issues with like, you know, is it a fixed zero or is it a like a floating local zero?

Fatty:
So, Josh, do you know for those new zip wheels that measure pressure on the fly, on the go, what method are they using is that zeroed locally or is that zeroed at the zeroed at the factory is it just telling you i mean is it giving you a number kind of similar to what hottie was getting in his lexus that is may have been reasonably accurate when he was in la but certainly not when he was at 10 000 feet you

Josh:
Know i i honestly don't know what's what's in there i like i said My experience with TPMS Automotive is that it's all based on this PSIA, yeah, zero. But I, yeah, I was not involved with that project when they did it, and I honestly have no idea what's in there. But if they followed, which, I mean, I would assume they probably did, you know, that technology was pre-existing from automotive for years and years. I would imagine it's PSIA based. But it could, I mean, it's either that or it's a fixed zero. I think either way, you're going to have some drift at altitude because, you know, it's a single pressure sensor that's always exposed to pressure. You know, there's no way to locally zero it. So it would have to be one or the other.

Fatty:
Something to look at another time. Hottie, such a missed opportunity in the

Fatty:
tool bag that I gave you in Leadville was an Electrico Ultimate. Ultimate you could have tested your Lexus right there and no I

Hottie:
Was focusing on the job of the day which wasn't the Lexus all the Lexus were sitting in the feed zone I suppose I got to ran down the record but I had like five people to feed that day fatty I'm not going to be you know oh yeah I

Fatty:
Appreciate you doing the job but in the name of science man in the name of science All right. Hey, we have got a product suggestion from coming to us through the Marginal Gains Hotline, which is 317-343-4506. This is from Chris in Portola Valley, California. I'm actually super interested. He texted this in. You've convinced me and the bike geek world that the low damping of silica bar tape is more comfortable. Why not make shoe inserts, footbeds, and hoods as well. As someone who would really like some more comfortable footbeds, Josh, I love this idea.

Josh:
Oh, gosh. Yeah. So great question. And we've had people want us to make all sorts of stuff. I think, honestly, probably the best thing we could make with that tech, and it's just not our specialty, but would be a saddle.

Josh:
So just think of that what you may, but it's something that's actually you want it to be squishy and so you want it to be a very low hysteresis squishy the the thing with shoe insoles is your your ideal shoe insole is rigid um you want it like formed to your foot but you don't want any give in it at all and so the the fastest uh yeah the fastest best thing you could you could do to make a shoe insole would be to just make it like a carbon fiber uh or or something like that, so it has no squishiness at all. Now, in a running shoe, totally different story, but for cycling, yeah, we went rigid. And then, you know, for things like hoods, the challenge there is just that, you know, they're actually incredibly, the rubber that you use to make the hood is incredibly low hysteresis, and it's also just incredibly low give. You know, there's very little compression. And so, you know, you would, you could make really thick hoods, but I don't think people would, like the look or the feel of them. But if you did want to make really thick hoods that were squishy, you would want to make them out of very low hysteresis foam. But yeah, I would say as it is, those are both things that are pretty optimal where they are with the current materials.

Fatty:
All right. Fair enough. This wasn't their only product suggestion. Here is another from the same listener. Why don't bikes have aerodynamic flow strip, flow trip strips, particularly on round head tubes and seat posts where the flow is potentially clean with laminar? Am I pronouncing that right? Laminar?

Josh:
Separation bubbles?

Fatty:
At transitional Reynolds numbers tripping flow, laminar to turbulent can improve CD by a factor of two. The Silica Aero Socks use vortex generators for this reason. Once again, I love our listeners. I love the idea of just being able to buy essentially a, like a decal that would make my Firefly Thai mountain bike more aero.

Josh:
So, yeah, so people have done it. And actually, if you get on the Googletron and search like zigzag strip or turbolator strip, something like that, you will find that the automotive world and the aircraft world, light aircraft, sailplanes, those sorts of things, this exists. And you can buy adhesive back. It's like a little zigzag looking decal that you can stick to things. And yeah, you can have at it. We've played around with them a ton in the wind tunnel. They're super fun to play with. But the reality is they still don't get you anywhere near making that thing aero, right? The equivalent of that. And so I think, you know, companies that are.

Josh:
Still doing things round, it's just what it is. If they're going to put time and energy and effort into making something more aero, you're way better off to shape it than just to add the trip strip to it. But as the consumer, if you already own the thing and it's round and it's less than optimal, you know, putting these things on there really, really can help. And we've even played around with, you know, putting them on a friend who does a lot of autocross. And, you know, we've played around with putting them on his car and, you know, playing with some of the modeling in CFD to see where you could place them that, you know, they might have the biggest effect. And you can put them on and then use downstream little tufts, you know, like a little bit of yarn that you tape on. And it is really cool. And you can see you might have like a separated zone and you've got a backwards tuft and you can put a little thing, a zigzag strip upstream of it. And all of a sudden it lays flat with the flow and you go, oh, we've done it. We feel like we've done something. So, yes, there are a ton of ways to do it. But yeah, hop on Google and you will definitely find probably three or four companies out there that sell exactly what you're talking about.

Fatty:
My titanium bike is about to become so fast.

Fatty:
Okay, I don't know if you guys watched Gravel Worlds a couple of weeks ago. Josh, I did see you about 30 times on the ad spots, but there was a racer with a disc wheel I saw on the course there for a second before and maybe after the mud. Hottie, did you see this guy?

Hottie:
Oh, I know who that is.

Fatty:
Yeah. Who is it?

Hottie:
That's Chase Work.

Fatty:
Okay, so a guy we've had on the show before. He was briefly in first.

Hottie:
Yeah, he was on a year ago. Yep.

Fatty:
All right. Well, sort of keying a little bit off that question, I've got a little bit more of a traditional question, a little bit more of a traditional bike setup on which wheel ought to go deep. This was called into our Marginal Gains Hotline, 317-343-4506.

Speaker3:
Hello, Josh. This is Barry from Missouri. I've got a question. You know, for years, we've been told that we needed a disc wheel in the back and as deep a wheel as we could handle in the wind on the front on our time trial bikes, or if we were really thinking aero. And now I'm hearing just the opposite. I'm hearing go deep in the front and go shallow in the back. As luck would have it, I just cracked my disc wheel on my TT bike and I'm injured. So I'm not racing anymore this season. When I set up for next year, do I need to be thinking deeper on the front and shallower in the back, or should I stick with the time-tested disc in the back and a medium section in the front? Always enjoy the show. Really appreciate it. Thanks a lot.

Josh:
Wow. Well, I'm wondering where he's hearing deeper in front, shallow in the back, because I've not heard that, and we're not seeing it. Anywhere, but I'll look around. So no, nothing beats a disc wheel. Nothing beats a disc wheel in the back. And a couple of things going on with a disc wheel that are beneficial here. So one, lowest wattage to spin. You know, you think of even now, and we do have some deep section and some, you know, three-spoke wheels that are similar aerodynamically in the wind tunnel from a drag perspective to a disc, but all of them tend to take slightly more wattage to spin, right? Because you're, you know, whatever the spoke is, you're.

Josh:
Breaking the wind as it comes over the top of the travel every time. And so there's sort of like the double effect. You get the good aero and you get the reduced wattage to spin. The other advantage of the disc wheel is it really does help to clean up some of that turbulent, just icky dirtiness coming off the legs and straighten that up to reduce the pressure wake off the back of the cyclist. So, you know, it's one of those things, one of the rare times I'd say that you, the thing on its own is faster. And then the thing on the bike with the rider, it's even slightly faster still because it has this cleanup effect. And then the third real benefit to it is you can generally get away with riding an even deeper front if you have a disc on the rear, because that disc wheel, it helps move the aerodynamic center of pressure of the whole system further back. And so it actually, you kind of think of it as like a little bit of like a stabilizing rudder effect.

Josh:
But because the aerodynamic center of pressure is further back, it just takes a little bit of the ability of the wind to steer the bike off of the front as it's shifted further back. So you're actually adding a little bit of stability to the system with the disc wheel. And for most riders, I mean, it's subtle, but you will absolutely feel it if you're trying to run a, you know, 82 or 90 or whatever millimeter wheel on the front.

Josh:
You will be more comfortable and more stable with a full disc on the rear than with a shallower wheel on the rear. So for those reasons, I would say in a TT, always run the disc.

Josh:
I guess the last thing I'll say about that, The analogy I've always used there is, You know, there's this kind of great asymmetry to the benefit of the disc wheel in terms of crosswind. And, you know, it's never not faster, but in some unique wind angles, it's off the charts fast. And so the analogy I've always said is, you know, my kids' school, they always have this charity wine pole, right? And it's all these bottles of wine, and it's 20 bucks, and the cheapest bottle of wine in there is $20. But there's one bottle that's, you know, like 500, right? And think of a disc wheel kind of like that. Like the worst case scenario is you're going to pay your $20, and you're going to get a $20 bottle of wine that you paid for. But the best case scenario, right, is that you're going to pay your 20 bucks, you're going to get the $500 bottle of wine. And, you know, that's how I think of the disc wheel in the wind, you know, like it's you're never not going to get your money's worth. But, oh, buddy, certain conditions, you are going to get so much more than you paid for that.

Josh:
Yeah. Always run the disc.

Fatty:
OK, Josh, one more question. This one sent in to us by alert listener Steve in Virginia, sending us this message to the Marginal Gains Hotline 317-343-4506. This is about an upcoming Kickstarter that I have seen as well. He says, say, fellas, check this out, a chain-mounted power meter. I'm dubious, but what does Josh and the Marginal Games crew think? Have you had a chance to look at this, Josh?

Josh:
Oh, I just clicked in, and I am, what the heck is going on? That is pretty, yeah, I'm trying to figure out how it works. It looks like it's got some sort of like... Like a little like almost like a jockey wheel in it and then it's so it's like a like a like a little credit card reader looking thing that sits over the top of the chain and then there's a like a stick coming out the front of it that touches your front derailleur and it and.

Fatty:
That's just to hold the gizmo in

Josh:
Place as far as i'm trying to like see if is it using force it's got two strain gauges like on that printed on the outside of it but like on the the housing of it, so i can't okay i i definitely gonna have to look more at that but i i mean i i would say i think on the upside is i don't know how well you're gonna read actually read power but you are gonna get all the noise out of this so i i think so if you you know if if you are sick and tired of your quiet, waxed chain bicycle, I think this will definitely bring the noise back. Holy smokes, what an interesting little thing. So, when I first read it, if you guys remember Polar, back in the early 2000s, did a similar thing. Well, they tried using the chain and it was, SRM had its pretty tight patents on the crank based and it was PowerTap, which was bought by Saris. They really had the patent game pretty locked down on the hub, and I think Polar who was heart rate up until then was like oh we got to get in the game and they came up with a system that I think is really clever and I've actually copied it in a couple of things that we've done in the chain um.

Josh:
A drivetrain tester that we built at Purdue, we've actually kind of put some of a similar sort of a system in there. But they actually put essentially, you could think of it as like a guitar pickup on your chainstay. And it would measure the harmonic, like the frequency of the chain. And so a different, the chain tension can be derived by its harmonic frequency in that moment. And it had a lot of challenges, essentially, you know, as the chain went up and down the cassette, that would naturally change – that would change the natural frequency of the system in that moment. And so it had to know what gear you were in now and a whole bunch of other things. And actually, Tom Anholt, who we've had on the show, he – when I first met him, he was online talking about how he'd basically taken one of these and done all this crazy stuff to it to make it work like 10 times better than it actually worked new out of the box. But of course, ultimately, I mean, it failed and went away and we've never talked about it again. But it was a – so, yeah, when I read this, I thought, oh, wow, I wonder if they're using frequency. But, no, this looks like it's just kind of a physical – like it's got some friction that it's putting into the system. And then it looks like it's using the load generated from that maybe fixed amount of friction to push against the stick.

Josh:
Pretty wild.

Hottie:
Hey, we want to hear your questions, power meters, you know, hookless.

Josh:
Please, no more hookless. Let's be done.

Hottie:
Okay. Maybe not hopeless so much. Here's how to submit, though. Text or call at MarginalGain's hotline, 317-343-4506. As you heard on the show, if you call in and record your voice, good chance you're going to get on the show. Old school, you can also comment on this or any episode at MarginalGain's podcast.cc. Yes, we do read those comments. I bagged a few questions right there. You'll also see all the links to the platforms for listening to the show at that website.

Josh:
Thanks for listening, and we'll be back soon with more questions and answers and scams. Thanks for listening to Marginal Gains. Got to lean into that. Ooh, maybe we'll get some hate from some dentists.