Ask Josh Anything #007

We're back with a new set of questions for Josh, digging deep into the topics super-nerd cyclists care deeply about. We talk about the products that intrigued Josh most at Eurobike, find out what size (diameter and width) he'd make road wheels be if he could start from scratch, speculate on whether the very aero-looking Ceepo Shadow-R is actually aero, consider marginal gains in gravel races, ask whether it's better to wrap cables together or keep them separate, ponder the age-old question of tubeless vs latex tubes, and...ponder marginal gains opportunities in inline skating. (Hey, rollerbladers need marginal gains love, too.)

Got a question you’d like to ask? 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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    I have to admit this content was very worthwhile. I discovered you with a google search and was rather stunned at your rank for this article.

  • Eric Reid

    A nit to pick about the “mantis” position as referenced by Antonio in the podcast… while hands are trending higher than in the past, this is really not exactly similar to what Floyd did way back when. UCI rules limit length, but triathletes are not constrained by those rules. The hands are higher, if done properly, because reach and stack are added, with the intent of improving comfort, power, and the Cd of the overall fit, and not necessarily the watts +/- of higher hands. This is also why the tilt is required. As a fitter and reasonably average athlete, even if the net effect was a loss of watts, it’s still the preferred method for long course triathlon fit due to the efficiency and other ancillary benefits.

  • Peter

    Thanks Josh,

    I missed that answer and thought my messages were coming as SPAM to you or something… so tried with two different email adresses… sorry about that.

    Anyway, so looking forward to hearing your answer about the Zipp 858 in a future episode… maybe in ask John episode #10 ! :-)

    And thanks for providing the link to Chung Method, have read it before will do again until I find how to get proper CRR numbers, for now with Golden Cheetah I’m able to play with the correct elevation and make CdA pretty relevant but that’s when fixing a CRR value, so I’ll try and get smarter with that.

    Thanks again !

  • David Ward

    This might be my new favourite podcast. Awesome!

    2 questions and a comment.


    1) I have read in a few places that the high heat absorption of dark colours also means dark colours let go of heat faster and as a result, the wind convention effect at around 22kph or higher means dark colours are cooler than light colours at that speed (or faster).


    1) Aero over weight.

    Using best bike split, this looks very clear. But when you add in the extra element of riding in a 50 rider size bunch on the flat…..are the aero gains of an more aero, but heavier wheelset or frame mitigated to the point where weight starts to matter more when you have a main climb in the race or course? Assuming you never take a turn on the front of the peloton. Does this explain why marquee climbers still stick with light bikes over aero bikes in the pro tour?

    2) If you have aero data on a wheel, tested in a tunnel, presumably on it’s own or as the front wheel, what is the general consensus of the type of aero performance reduction would you expect for the back wheel (behind a frame, churning legs and crank etc)? All companies would post aero data of a front wheel hitting the clean air, so you wouldn’t just double that for 2 wheels, or would you? Or does it vary so wildly that there’s not a typical range?

    Thanks for the shows! Love them.

  • Josh Poertner

    Ha!! Yes, that is a beautiful example of the power of aero.. one the body is horizontal the CdA goes WAY down and you can see that he just begins accelerating! Of course they don’t do this in the pros because it’s too dangerous and leaves the rider with too little control of the bike. There is enough talk about maybe penalizing riders for some of the extreme positions being used while clipped in, so I’m sure this would be banned by UCI straight away.. Thanks for sharing, love that video!

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