AJA #32: Marginal Gains for Commuters, Big Riders & Motorcycle Chains

I have a question that has been bouncing around in my head since an episode you did a month or two ago.

Someone asked you a question about whether gravel tire inserts change rolling resistance. You said they didn’t and went on to answer another aspect of the listeners question. At the time this made sense to me because the pressure and contact patch of the tire are not affected by the insert. But I cant stop thinking that having the insert in there would have a similar effect as having a volume spacer in a suspension fork and so would change the effective “spring rate” of the tire (not certain that is the right term). If so, surely this must have an effect on the tire performance over various surfaces and presumably would impact the Silca pressure calculator results.

This does align with my experience. I run Vittoria inserts in Rene Herse 42mm gravel tires on my singlespeed gravel bike and I feel that the inserts do effect the feel (and efficiency?) of the tire over rough surfaces. I also use your pressure calculator all the time when preparing for events and races so am interested in your thoughts on this?
(I do recognise the irony that I am asking about marginal gains around tire pressure for a singlespeed gravel bike which is purposefully inefficient – but that is a whole other discussion).

Cheers
Tim

I ride multi-day ultra races. Q to Josh. While riding in crosswinds, should I turn my head/ helmet to meet the yaw angle or should I keep my Kask Utopia aero helmet pointing straight where I’m riding?

This past season I upgraded my road bike tire setup to Continental GP 5000’s 700×28c tires with TPU inner tubes on an internal rim width of 12.5mm and an external rim width of 19.0mm. I am on the bigger side of road cyclists (6’4” @223lbs.). This tire, tube and rim setup produces an audible rubber squeaking sound (like rubber shoes squeaking on the floor) while rolling on smooth to rough asphalt. Is this dissipating energy in the form of sound vibration costing me watts? If so, what are possible solutions to this? Wider rims? Different inner tubes? Optimize tire pressure? Lubricate inner tubes?
Thank you.
Love the show!
Mike W. Buffalo NY

two tire Rolling resistance questions: Is there a penalty for running a tubeless tire(because they’re faster) with a latex tube(my roval rapide wheels are not tubeless compatible)? ive heard they run about the same CRR as 20ml of sealant. 2) do you have a rough CRR for the difference in say 26mm to 28mm tire when accounting for vibration loss, or is it purely a measured width issue? my rapide wheels running a 26mm measures 28, versus my 28 which measures 30. i know aerodynamically the “loss” in wider is outweighed by the smoother ride of 28 vs 26. i guess im asking, am i losing too much by riding a 28 that measures 30 vs a 26 that measures 28. or am i just ultra deep into the “it depends” world lol

Hi Marginal Gains Podcast,

After having listened to all the episodes of this podcast there seems to be a common theme that CRR is maybe the hardest thing to measure on the bicycle. Would it be possible to go into detail about what sensors could be developed to measure this or what has been tried historically? Something that measures the flex of the tire? or maybe reconstructing CRR from various sensors that measure strain or vibration in the wheel?

Cheers,
Hal