AJA 28: When are 2X drivetrains NOT worth aero, chainline and aero costs?


It's a no-topics-barred Ask-Josh-Anything episode of Marginal Gains, and (as usual) Hottie and Fatty get their own burning questions to the front of the line. Hottie desperately wants to talk about F1 porpoising and its connection to Hopf bifurcation. Josh accomodates. Fatty overheard a rocket scientist proclaim he wouldn't trust a repaired carbon fiber hardtail for technical mountain biking and now Fatty's scared about whether he's OK to ride. Josh reassures Fatty with the sage advice that "it depends." We then dig into actual listener questions about what kind of Ti alloy Silca uses when 3D printing, the pros and cons of 1X vs 2X drivetrain setups, and...how one might marginal gain a triple stroller in order to set a world record 10K pushing this pram. As always, this AJA episode's a great mix of thoughtful, serious, practical and silly. Don't miss it!

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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  • Bryan Larsen

    Question for next AJA: when and how do account for centripetal forces applied during velodrome testing/modeling and how does this affect Crr?

    Ex. We know that surface irregularities are the main contributing factor to Crr out on the road but what about on a velodrome? We do know that we need to account for micro irregularities on any particular track, but how do we account for the banking? Considering the speeds of IPs and TPs these days, I can’t help but imagine that the normal force during banking is incredible. And as such, this has to influence Crr or effective rolling resistance? Additionally, what else is impacted by this banking and what other factors should be considered when trying to project and model a target speed/time? Since speed is not actually constant, I’m struggling to understand how best to find out how much power is needed to hit a target pursuit time and what is controllable (like tire pressure) and what isn’t?

  • Neil Mackley

    Hi. I was listening to the pod regarding the gains and losses of 1x
    I race TT in the Uk and normally would run a single front 60t narrow/wide chainring and 11-23 on the back. On less flat courses I would change to 11-25 or even 11-30. I was interested in the added friction of narrow wide over a standard chain ring. I generally race on fast courses with a PB of 19:48 for a ten at the age of 59.

    My question is when would a 2x be more effective over the 1x? For sure I get a noisy chain when I’m in the 28/30 sprocket. But it’s interesting to note few pro teams run 1x setups, so maybe a 2×55and 11-23 could be the best all round option. Or maybe a 58 on the front and 11-23 be better.

    Best Regards

    Neil Mackley

  • Travis Verhoff

    @Matt there wouldn’t be any more energy stored by having more weight on a climb. It would also be rare to have a fast descent of any length without having to scrub some speed through braking at some point. At a fairly slow speed weight really is the main thing slowing you down and with much speed at all, aero is going to be the main force to overcome.

  • David


    Has anyone tried creating trip strips/turbulators with their leg hair? 🙋‍♂️ I have


    This should work, right?
    All in an effort to go faster :-)

  • Matt

    What’s your thoughts on weight and its reduced importance compared to aero in cycling due to the fact that mass (while slower on a climb) is being converted into potential energy which is then transferred into kinetic energy once you reach the top and start descending provided you are not scrubbing energy via braking or other means on the downhill. if thats the case, aerodynamics and rolling resistance would be paramount as energy is conserved and simply changes forms when it comes to weight (potential energy/kinetic energy) and you are trying to reduce energy being wasted (aero drag/rolling resistance, braking)

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