Debating the Fundamental Truths of 32-Inch Wheels

Published September 16, 2026 02:19PM

Welcome to Dropped, a new weekly road and gravel cycling newsletter from Velo that brings you the latest ideas we’re debating endlessly on group rides, and a look behind the scenes of our coverage.

For the tech team here at Velo, our podcast recording is one of the best 90 minutes of work we get to do every week—besides the on-the-bike testing of course. It is the perfect opportunity to bring our work as cycling journalists into a medium where we can talk, argue, and laugh about tech as friends. (Yes, Josh and I are friends, even though his takes on some cycling things make me want to scream.)

The stories and videos we produce are always the core of our work, but the podcast is where we can garnish it, so to speak.

Yet sometimes a topic comes up where we need to clear out and let other bike-industry professionals get into the nitty-gritty details of where cycling will go next. Real audio journalism. This week, we are privileged to present exactly that: a debate between two significant voices in the industry, John Karrasch and Jan Heine, about the viability of 32-inch wheels.

Karrasch, aka flexfitbyjohn on Instagram, is the preeminent voice in real-world tire testing. His use of Chung Method testing has generated a massive set of rolling resistance data that has fueled the adoption of higher-volume gravel tires. The testing has also produced results that demonstrate that 32-inch wheels can improve the rolling resistance of gravel and mountain bike tires by 10%.

Heine is the CEO of Rene Herse, an early producer of gravel tires and a longtime proponent of the speed of wider tires. Heine has been one of the most vocal and persistent critics of Chung Method testing, as well as Karrasch’s claims that 32-inch wheels are faster. Since Karrasch first posted his findings on 32-inch wheels this spring, Heine has posted a series of long blog posts that rebuke the testing, citing his history of roll-down tests, and raising questions around the Chung Method.

This has played out as an on-and-off, back-and-forth exchange since the eve of the Sea Otter Classic back in spring. For the real tire heads out there, like myself, it has been an online science fight unlike any other.

It has even extended here to our work at Velo. In many of my articles around gravel tires and the validity of 32-inch wheels, I have referenced Karrasch testing. Multiple times, commenters have responded to those articles with Heine’s blog posts, arguing against the speed the Chung Method showed. All of this got me thinking: what if we got these two very different, but very insightful people together for a discussion on the podcast?

Maybe a true debate on the Velo Podcast could even be a place where we can find some common ground and better consensus around these very important topics.

To make this podcast happen, I reached out to both Karrasch and Heine to get the ball rolling. I also recruited Mike Levy, our trusted host, to lead the discussion. Personally, I felt like I was too partial to Karrasch testing to be an impartial host, and it would benefit the discussion to have Levy, an informed outsider, lead it. The project took multiple email chains, many texts, a few calls, a long email to Levy explaining the whole thing, and a change of location to land the plane, but when we did, it felt like we managed to create something well worth the effort.

In the end, the conversation went well, and both Karrasch and Heine made good points. I still find myself aligning more with Karrasch and the Chung Method testing he does, although with someone like Heine, who has such experience in this space, it always pays to listen to his perspective that is always going to be true to his depth of knowledge. Nevertheless, maybe you see it differently! Let us know below what you thought of the debate.

When the podcast dropped on Friday, I was so proud that we were able to pull this off. The bike nerds were having a wheelie big fight, and we were able to bring that debate to the right forum. While our tongue-in-cheek title might sound dramatic, I do think it does a good job of mixing the seriousness of the discussion with a healthy dose of levity. Nobody here is an enemy; everyone is just here for the love of bikes and the pursuit of making them faster.

Who do you align with? Are 32-inch wheels an important topic on your radar? Let me know your thoughts, and also if there’s another deep dive topic you’d love to hear either us or other experts debate.