Agreed, and Dylan acts like a normal human most of the time and then works in “backwards hat Dylan” in small doses. That works (at least for me).
And I struggle with the Bonk Bros podcast. They hit on some good things from time to time, but it’s a hot mess most of the time. If I’m stuck driving for 10 hours and have exhausted all other content, it might make the playlist.
But more power to these guys for building a following. Way better than I could do.
Haven’t watched the video but I think the take away from reading commentary here is that tire choice still depends on the course profile. MTB is not faster all the time. This was brought up a lot by the pros at Sea Otter. With fairly smooth gravel & a decent amount of pavement, a narrower tire (42-47mm) seemed to be the best choice. But on a course like unbound… probably not!
To me that’s what makes it fun. Kinda like in car races in adverse conditions. You going with the fast tire or the slower one with better grip? Makes things interesting.
Do you mind refreshing me on how CdA fits into Chung testing? Is it one of the inputs that the algorithm cancels out in order to get CRR, or is it baked into the process somehow?
If I understand correctly, I think you’re estimating CdA at the front end and so it’s not part of your results for CRR. But then are you putting it back in for your ‘watts to ride at 18mph’ charts (and similar)?
I’m trying to work out how much we should/shouldn’t be considering aerodynamics separately from your results.
This guy is the king of bro science and doesn’t deserve any views. Kinda sucks that hes gonna make money on U-tube off of crappy testing
Yes, you need to have a CdA in order to get CRR from Chung testing.
I have been doing this a few years so had a good idea what my old gravel bike was CdA wise. I also had seen a few wind tunnel tests so knew my ballpark numbers.
From there, you can zero in tighter with shallow grade climbing tests with a big spread of speed and power. This makes it where only one match of CdA and CRR makes any sense for all the runs.
This actually gets even easier if you test on different areas and with different tires over time.
This gets pure absolute rolling resistance and you can throw total aero back in whenever to give a full view of system performance when needed.
This photo shows an example of this with uphill sections alternating between like… 150 and 375 watts per lap.
Ok thanks. Really helpful. So, in terms of interpreting the data you’re reporting, it sounds like what we need to know is that it’s pretty reliably removed from your CRR numbers (not just based on your own historical experience but also refined/confirmed within the algorithm itself to a degree).
And when you’re adding it back in for the ‘watts at XXmph’ charts, you’re using the same estimates that got checked and refined in the algorithm, so again it’s an estimate but based on far more than just historical reference points?
Yeah, correct on the first part. If you want really accurate rolling resistance values, variation in aero drag is really important. For example, in colder weather I know how much extra drag my winter kit has vs summer.
On the second part, if I added it back in to give a total wattage for a rider and bike system at a speed I would often just pick an average gravel setup CdA like 0.380
In the case of more specific wheel testing or something I would use the exact value from me on my bike during the test.
After reading through half the thread (which is around 700 posts or 1.5 hours of Zone 2) I am still not sure if my next ~40mm gravel tire should be a Schwalbe G-One RS Pro or again a Specialized Pathfinder Pro. 
I ride 50% asphalt, the 42mm Pathfinders are a great all-rounder, though a bit „washy“ on multi-layer gravel, especially on descents. Also not the fastest on pavement, that doesn‘t matter that much but a bit faster would be nice. The rear tire held up for 6k km and I had one flat only which is decent.
The Schwalbe G-One RS Pro is regarded as kind a “modern version” version of the Pathfinder Pro, right? (grippier + a tad faster) Sadly I don’t have more clearance.
Tufo Thundero
So unbound in 2 weeks. I have two wheel sets and currently have on front a 47mm pathfinder and 2.1 thunder Burt. I can’t fit any larger than the TB. I’m very reluctant to run the TB at unbound due to puncture risk.
With that in mind, I still want a backup front tire to the pathfinder 47. Preferably something that measures 52mm or less. With the new offerings this year, suggestions on a 50ish-mm puncture resistant, reasonably fast rolling tire? I’m thinking about the Schwalbe G-One RX, but not sure how puncture resistant it is. I think that Dilman? Ran it (and I may have been part of the discussion in a thread and can’t find it) and he flatted a few times, but unsure if that had to do with his set up, more info surrounding the flat, etc.
Thoughts?
The new Specialized Tracers are excellent
how many watts does your cold weather kit cost you vs summer?
6-7 watts 20 mph
I suspect Sofia and Matt Beers will be on them at Unbound.
An hour and a half ride last night, 1/3 of it on tame dirt single track, and I absolutely agree! I got them in 45mm as I couldn’t find the 50 in stock, no regrets as there’s plenty clearance on the CruX. Conditions currently are about as dry as they can possibly get, to the point where top surface has loosened so it is closer to loose-over-hard than anything. Plenty grip compared to a file tread (Caracal), and I didn’t feel noticeably slower on road.
Please do this on every thread from now on. Where else can you get an estimate of the time required in zone 2 to read a thread?
Made my day!
I’ve been in the tunnel and this is very accurate. I get a nice chuckle when I see advertisements from kit and equipment companies claiming small percentage gains. These are always within the margin of error and could easily be manipulated.
Don’t always believe the hype.
Thanks haha! 
There is a function like this which shows reading time (at least on desktop, not in the mobile version):
I started reading on the trainer, I know it’s strange…
Funny because there’s a lot of Dylan Johnson gospel in this thread.
Anyone have thoughts on the 50 mm Race King? The 2.2 won’t fit my bike and the 2.0 is non-back chili obviously. Anyone run these? Any other recommendations in the 50 mm family?
