A favorite topic on the Marginal Gains Podcast is rolling resistance, also known as CRR. It is one of the cornerstones of this show. While we have interviewed aerodynamic experts who have devoted hundreds of hours to CdA, we have found very few who have made CRR their passion. Tom Anhalt was an early guest but we can't think of another since. That changes with this episode.

John Karrasch makes a living from bike fittings. But John has made a name for himself through his tire testing. Using the Chung method, John has been putting tires to the test to see which ones live up to the hype. In just more than a year, he has amassed an impressive database covering just about every brand you can name. The beauty of John's work and results is he shares it with all of us at no cost.

In this interview, John shares his early beginnings with the Chung method, how he has refined his testing, and what some of the key learnings have been. The only thing between your bike and the surface you ride are your tires. John is one of a few who has been trying to quantify just how much power it takes to keep those tires rolling.

It's funny how tubeless freed is from tubes and years later some of us turned to putting something else in the space between rim and tire. Namely inserts. Most of them are foam and a real struggle to install. Then there's OPTIS: The Odyssey Tire Pneumatic Insert System. Cool acronym that basically means "inflatable insert." The people at Odyssey will be quick to say OPTIS is not a tube. While it does press up against the sidewall when inflated, it's job is just like a foam insert: to prevent pinch flights. OPTIS weighs significantly less than a foam insert, and its behavior is adjustable. We spoke with Jacob Hinton from Odyssey on this unique product that recently gained notoriety during a spring classic.

Up next is a look at radial tires for bikes. 32-inch wheels have garnered most of the buzz in 2026, but radial tires are also making waves. Two big tire makers have jumped into the space and made claims of enhanced grip for gravity-style riding. A third company, Delium, has also been developing radial tires. We hear from this lesser-known maker about how tech works and its potential in the bike space.

Our 50th Ask Josh Anything! That's a lot of questions and answers and "It Depends." Thanks for hanging with us to the mid century mark. On the Q&A agenda this episode:

• The perfect padding for aero armrests.
• Tire inserst for Unbound
• Breaking in tires for best CRR
• The right gears for an Everesting
• Narrow flat bars for Leadville
• Gravel wheels on a road bike and the rule of 105

Our first episode that covered the topic of 32 inch wheels focused on the bigger wheels being used on mountain bikes. Daniel Yang of Neuhaus Metalworks put us on a prototype rigid mountain bike and took us for a ride. It was eye opening. But it also raised questions.

At Sea Otter we saw a shift by some builders and manufacturers as to where they thought the big wheels might perform best. Drop Bar bikes supported by 32 inch wheels were just as common as Flat Bars at this year's show. Straight line speed and all day comfort was the reason given for developing a 32er gravel bike over a mountain bike.

Like a lot of bike media, we set out to get some answers on the future of this "Big Idea." Daniel Yang is back with his report card on the trend. We also hear from two companies that were showing Gravel bikes that attempt to answer the question: Is bigger, better?

We're not afraid to share an opinion on this show. At no time was that more apparent then when Josh let his thoughts known about hookless road wheels. It caused a bit of a reaction in the industry to say the least. And while we have some firm beliefs on certain technologies, we also believe in fairness. Which is why at Sea Otter we gave some wheel brands a platform to explain what has become a somewhat divisive topic.

Our guests work for three brands: ENVE, CADEX and Mavic. Two of them stand behind road hookless as a high performance and safe feature. The third has stuck with hooked rims. All three bring a unique perspective on what it takes to secure a tire to a wheel. We also talk to these wheel makers about their brands as a whole: what's driving innovation, how pro peloton success turns into sales and for one of them, what it takes to revive a heritage brand.

It feels like now more than ever it is important to find sources of information and reporting that are trustworthy. It used to be fairly easy: subscribe to a credible outlet and trust that said newspaper or magazine would have guardrails in place to get it right and to exercise fairness. As the internet and social media became the predominant sources we rely on, a lot of those guardrails were knocked down. It could be argued that the system in place now is more democratic. More wide open. More voices. But along the way the trust factor has taken a blow.

That's why we wanted to talk to Ben Delaney. Ben came from the old school ways of cycling reporting. He got a degree in journalism. He got a job at a magazine. He did the work and made his way up. Like a lot of his colleagues, he also took his lumps as traditional outlets succumbed to the pressures of lower ad revenues and tighter budgets. After being let go more than once by Velo, Ben decided to go solo.

These days you can find Ben making videos for his gravel focused "The Ride" YouTube channel. It's one of Josh's favorites, so much so that Silca supports the channel. "The Ride" is a great place to check the latest in dropbar, offroad tech and trends. But this interview is less about gear and much more about the landscape of cycling media. How it got to where it is and what it needs to keep its credibility.

Josh has spoken on many occasions about his time with Zipp. The engineering. The R&D. The wins. The fails. Josh was part of a team that changed the scene, both for pro and amateur racers.

At the head of that team was Andy Ording. Andy took over Zipp from Leigh Sargent in 1998 and guided it through its glory days that Josh is so fond of. Andy's journey to carbon wheels is far from linear. A native of South Africa, he eventually found his way to the states via motorcycles. Andy's strengths are in sales and logistics and those strengths eventually led him to the bike industry.

In this episode, Andy and Josh swap Zipp stories. They also share insights on what it takes to foster new ideas. How empowering people is one of the keys to making the next great Marginal Gain.

Fatty drops a bombshell: he's turning 60 and attempting an Everesting challenge this June — and he needs Josh and Hottie to marginal-gain every aspect of the ride. From course selection and bike setup to tire choice, chain wax strategy, pacing by heart rate, and why a leaf blower might be his secret weapon, the crew breaks down how to get a self-described "card-carrying AARP member with a paunch" up 29,029 feet of climbing on a decade-old bike.

Most of us hardly give those water bottles in our cages a second thought. It's plastic. It's there. It's got what we need. But in the late 20-teens, Carina Hamel and her partner started giving those bidons and second thought. And a third. And a fourth. And like a lot of new ideas, they thought, "There's got to be a better way." Their critical thinking led them to develop Bivo Bottles: stainless steel bottles that fit properly in bike cages.

Since late 2020, Bivo has been trying to convince cyclists that they are better off with a metal bottle than plastic. They've made progress but the ride has not been smooth. First came Covid, which delayed their launch and stalled their grassroots marketing campaign. Then just as they started getting momentum, along came massive tariffs which threatened to end Bivo altogether.

But Bivo is still here and as of this episode, celebrating a five year anniversary. We talk to co-founder Carina Hamel about their ideas, innovations and a chance run in with a NASA engineer.

Josh answers listener questions about essential race-day gear, from what to pack for Cape Epic to whether digital torque wrenches are worth the beeping. We into Lifetime's controversial drop bar ban at Leadville, exploring whether safety concerns justify the change and what aero options remain for marginal gainers.

For most of us getting into a wind tunnel is but a dream. Tunnels are hard to find and harder to afford. As an alternative Josh has recommended the Chung Method. It's proven yet it does take some expertise to get right. What if there were something in the middle? Something that is more accessible and less expensive than a wind tunnel yet doesn't require the hours of commitment and trial and error of field testing? Our guest believes he has just that. AiRO may sound like a company that is trying to latch onto the "AI" craze. But its founder, Ingmar Jungnickel, has been into cycling aerodynamics long before Chat GPT became a thing. He has a degree in engineering, he's developed on-bike aero hardware, and he worked for Specialized where he logged many hours in that company's wind tunnel. All of that, along with a chance opportunity to work with speed skaters, led him to develop a CFD program that attempts to make cycling aerodynamics more accessible. Ingmar's back story includes meeting are own Josh Poertner. But the real story here is how good Computational Fluid Dynamics has become. The potential of AiRO and its data even blew the mind of Josh as you will hear in this episode of Marginal Gains.