Ask Josh Anything #011

Marginal Gains type of question with regards to indoor riding on a trainer. I used to ride on a “wheel-on” fluid trainer with my old aluminum frame & wheel bike. This trainer required a riser block to level the bike. I recently purchased a Wahoo Kickr, and have been very pleased with the handful of rides I’ve gotten so far on my new Carbon bike (Scott Addict). The sound level and not requiring a block to level out the bike has been a welcome improvement. That being said, I doubt the engineers designed: frames, forks, wheels, hubs, etc…to be ridden on a trainer.

Question(s): Would a riser block under my front wheel (Zipp 303 with 28c GP5000 tire and butyl tube) help/minimize additional stress from going into the wheel (wheel, spokes, hub), fork, head tube, or headset? Should I be checking my front tire pressure periodically when I ride inside on the trainer to keep it at a higher or lower pressure than I would run on the road? Are there any other things along those lines that potentially would minimize any effects of riding inside?

I know, I know, it depends…

Thank you; I enjoy the podcast.

I was using the new SPPC (Silca Pro Pressure Calculator) form and a thought came to me. What would happen if all other things being equal (ie bike frame, wheel etc) but all you did was change from a 25 700c tire at optimal pressure to say a 32 mm 700c at optimal pressure. What is the rolling resistance difference. I know tread can have an impact so for this thought experiment I am suggestion the same tread profile? There is an inertia difference due to tire weight but what else comes into play?

Is there any chance a dirty frameset and wheels can replicate a dimple-like effect on its surface, and be more efficient? Please justify my lazyness.

Great podcast. It’s rare to find someone with Josh’s knowledge that is still so open to learning and new ideas.

I’d love to hear Josh’s thoughts on a few areas:

Has he ever come across any data on how BB stiffness effects actual speed, especially in seated steady-state efforts?

Pretty much all wind tunnel, rider+bike, data shows drag reducing as yaw increases. Outdoors this doesn’t seem to happen! The opposite, data from outside suggests effective CdA increasing with yaw?

There are exceptions of course. Selective shelter along a race route, traffic effects due to wind-shifted turbulence etc

What kind of accuracy and precision differences have you seen from various pumps at track pressures, say 170-180psi?

Keep up the great show, loving the YouTube vids too.

Justin

Hey Fellas, love the podcast, it’s sustained me on long, wet British winter rides :)

First, many years ago I was a sports scientist (earning a PhD) and my post grad colleagues then were working on head cooling as a mechanism of improving performance in the heat. I thought of this in your section of cooling during Zwift races. I’d suggest that, in short races at least, the effect of head cooling would be greater than body cooling due to the reduction in perceived effort (see Hutchinson’s excellent Endure book for a summary). In longer races where significant internal heat would build up that would become more important… Either way caffeine has been consistently shown to reduce the impact of heat on perceived exertion so is definitely recommended for most athletes.

Anyway, I have a question. What would you say would be the most effective strategies in ultra bike packing races (on road)? Even though the speeds are relatively low, over 1000 miles little things add up. I’m thinking tubeless, aero wheels, riding at night when it’s cool and quiet, chain waxing (and carrying lube), aero baggage etc. What about dynamo hubs Vs battery lights? I know the answer is “it depends” but If you guys were racing an event like this, what would you focus on?

Thanks again for the podcast, takes me back to my sports science days, happy memories!

Luke