Ask Josh Anything #002

Q&A Episode 2 –

In this Q&A episode of Marginal Gains, Josh answers questions about whether front and rear tires should have symmetric or asymmetric air pressure (and why). We dig into whether no-name Chinese handlebars and wheels are a good deal, or just cheap (and why). Josh analyzes the ongoing thread at Slowtwitch that shows little Crr difference between 23, 25, 28 and 32mm tires. Josh answers why pros are (still!) sticking with tubulars. And there’s more. So much more (including — weirdly — that both Hottie and Fatty talk about how Silca and this podcast are beginning to affect their respective marriages).

Interesting Links, Sources, and Additional Reading From this Episode

Chung Method: The original paper

Tom Anhalt’s sensitivity testing of Chung

Abraham Olano winning ’95 worlds on a flat tubular

Got a question you’d like to ask Josh? Text or leave a voicemail at the Marginal Gains Hotline: +1-317-343-4506. You can also email us at questions@marginalgainspodcast.cc, or just leave a comment in this post!

Subscribe using your favorite podcast platform (but be sure to rate and review us on Apple Podcasts)

9 thoughts on “Ask Josh Anything #002

  1. “Soft and comfy?” Are you sure you are a cyclist? I thought cyclists **want** “firm” underneath them. Listen to your wife (or Josh in this podcast), your preferences will lack the handling stiffness you need in a couch. 😉 (Also, be sure to get the left/right pressure bias in the new couch cushions, you’ve probably been getting that wrong… don’t consider just the static position. 😀

  2. Very nice story about vortex shedding. Two things:

    1. Samuel Karlin said: “The purpose of models is not to fit the data but to sharpen the questions.” This seems like a perfect example of that.

    2. Re: time averaging in the wind tunnel: that’s pretty much how “classic CdA field testing” worked, and small changes in speed or power or slope were considered errors. I look at the data every second, so I include accelerations and changes in slope.

  3. Serious question… You talk a lot about your time working with pro-teams during the 2000s. How did you and the teams you worked with sort out the performance gains that came from better gear, better training, and uh… better doping?

    1. This is a great question and one we’re working into a future episode in a way that is as factual and balanced as possible.. we are targeting a TdF sort of timeframe for this one.. stay tuned!

  4. Thanks for answering my tubular question. I kind of (tongue in cheek) dislike your answer, as it feeds my innate desire for lightness, as i am a weight weenie by nature. And my wife would hate you if i bought another wheel set to save 200-250g… but if i need to throw you under the bus, i will. I am sure you will understand.

    I took a 0.5lbs hit on my road bike (now 13.5lbs) to go with “practical” deep section aero clinchers that are tubeless ready. My logic, and looking at data available to me, was that any advantage from losses in wheel weight would be offset by increased rolling resistance found in off the shelf tubulars (and i wanted to stay away from the really fast but fragile stuff like the corsa speed… where the tubular lags behind the tubless in crr). Plus i could not deny the benefits of aero wheels everywhere else. And i do not race.

    I look forward to your episode on wheels and tires. I put a lot of thought into my choice of rim width/depth, weight, pressures, and tire width needs given my rider weight (low).

    1. I think it is easy to over attribute the benefits of weight.. I even have some data that very light wheels and tires are detrimental to cyclists who don’t have perfect pedal strokes… the theory being that there is something of a smoothing effect to wheel inertia when it comes to power/acceleration on steep climbing..Long story short, we love to obsess over weight, but it’s really hard to make it matter in small quantities when doing the math. Similar to stories told previously, if we take 1kg off of a bike and have a rider do a standard lap of a hilly loop.. then show that data comparison to the engineer without telling them the change.. they will struggle to accurately find or attribute any performance difference. Whereas we change Crr or aero by just a few % and it can be discerned almost instantly.

      Beyond that, I’m happy to take the blame for any cycling related purchases that need to be made, but almost purely on psychological grounds as bicycles make people happy and going fast makes people really happy.. I have a talk I’ve given all over the world and in it I have an equation that says: Speed/Effort=Joy

Leave a Reply

Your email address will not be published. Required fields are marked *