Marginal Gains Cycling Podcast, Presented by Silca

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.