Ask Josh Anything #004

Q&A Episode 4 -

We didn't set out to turn every other episode of the Marginal Gains Podcast into the "Try to Stump Josh" game show, but at least 2/3 of the hosts of the show are glad it worked out this way. In this episode, we ask Josh what he thinks of Zipp's new MTB rims, puzzle over why the GoPro is so non-aero (and how to mitigate that non-aero-ness), discuss aero cranks and why they aren't any bigger of a deal than they are, talk about why it's faster (sometimes) to ride the white divider line, wonder why ceramic bearings don't (usually) turn back into sand, detail the steps for figuring out CRR in the field, explain why heavier riders descend faster, and — believe it or not — more. Enjoy this new Q&A episode of the show that makes a big deal about the little things, and how those little things can be a big deal.

Got a question you’d like to ask Josh? Text or leave a voicemail at the Marginal Gains Hotline: +1-317-343-4506 or just leave a comment in this post!

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  • John

    Can you explain the martin equation and how you ise it to advise riders on gear selection for varying courses.

  • Frederic CREMERS

    Hi Josh (and the rest of you),

    When Specialized introduced specific aero clothing a few years ago, it came in an overwhelming amount of different sizes to to be as close as possible to any riders body and avoid aero losses (ripples?). If I remember correctly, you also mentioned a trial of a very specific fabric in a wind tunnel that was ruined because the shape was not good and fabric flapped and that ended up being less efficient than any correctly fitted kit.

    Now to my question : How hard is it to bend a given fabric, because, if it’s too tight to avoid ripples, the fabric could be under tension and require higher force to be bent and/or stretched when your legs go up and down (aka pedaling). If you take a bib short and pull on it to stretch it you need some force, so you must lose watts when pedaling. Is is so marginal that it’s never been an issue? (I don’t think there’s anything too marginal in your eyes) or is the elastic nature of the fabric give you back the energy you just spent? Is it as always a compromise between tight and flat fabric vs a supple and easy to stretch one?

    This is a topic that mixes aero and energy loss, so I am very curious to hear your comments about that !,

    keep up the good work!

  • Bert

    Love the podcast folks – keep up the good work!

    re: the new Zipp 3Zero Moto rims

    Was the restrictive patent not applicable to Mello Boumeester as he had a very similar single wall carbon rim in the marketplace a full 3 years ahead of Zipp? Maybe he was behind the patent, although I figured likely not given he was a one-man show back then.

  • Andy

    Cycling cap. I tend to wear one in the winter to keep warm and in the summer to keep sweat out of my eyes. My question is – peak up or down?

    Kind Regards, Andy

  • Alee Denham

    Big fan of what you guys are doing!

    My question for Josh:

    We know that tire casing losses dominate until the breakpoint pressure, when then the impedance losses dominate. If we were to increase our tire pressure past the breakpoint pressure, can we theoretically reduce the impedance losses by employing a form of suspension – effectively lowering the combined rolling resistance? For example, by fitting a carbon seatpost like the Ergon CF3 and Redshift ShockStop stem.

    Many thanks,


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