AJA 24: Making Hydration Aero, Carbon Wheel Failures, & Wireless Braking


Josh answers a batch of listener questions, from the extremely practical to the fascinatingly hypothetical. Are pros flatting more than they used to? Has the balance between strong and light swung too far toward light? How do you make your hydration as aero as possible? What air pressure should be used for the back wheels on a competitive trike? And how good would electronic / wireless brakes have to be before you could trust them? We get into all this and more in this Ask Josh Anything episode of Marginal Gains!


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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  • Dave Minter

    Able-bodied Brits have been racing upright trikes since Victorian times, mostly time trials but also criteriums and occasionally triathlons. Josh started to pick up on transient loads that require higher tyre pressures (than just halving a bicycle rear tyre pressure) but he missed some more points.

    A trike can be cornered quite hard with an acrobatic rider (or riders, tandem trikes are raced too) and lifting the inside wheel is pretty common. 700C wheels will take an awful lot of sideload before folding, even on a tandem trike.
    Too low a tyre pressure and you will be riding on the tyre’s sidewall or peeling it off the rim. Neither is a good idea.

    Trikes have three wheel tracks and the back wheels hit bumps individually, jiggling the rider’s weight from one rear wheel to the other, particularly if the rider is sitting firmly on the saddle. Traditionally trikes have had two front brakes and no rear brakes because the rear wheels individually skid because of the very low weight/ traction on each wheel (worsened by load transfer under braking) and the jiggling mentioned above. The UCI stuck their nose in to paracycling and mandated front and rear brakes. The rear brakes are mostly decorative. Who could have expected that the UCI would make stupid rules?

    The best trike maker in the world lives a little west of London and, until this year, made most of the trike conversion kits or custom trikes for Paralympians and the rear axle for Quattrovelo velomobiles. http://www.trykit.com/

  • Nick

    Curious about the trike pressure recommendations, as using the silca tyre pressure calculator for my children I’ve noted higher pressures recommended than expected becuase I was expecting that 1/2 the load →1/2 the pressure. But the recommendation is only to drop ~10psi going from 90kg to 45kg. So for the trike why should he not be splitting the rear load across the 2 wheels and putting that in the calculator, instead of halving the pressure?

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