Jan Heine - knives out for side knobs

[HTupolev]

Originally Posted by spoonrobot

This is abusing definitions to bend reality.

It's an extremely commonly-used definition in engineering.

It can be disproven by sampling even a small numbers of GPX files.

Huh? The idea that GPS accuracy does not degrade with respect to sampling period is not a bold claim.

If every point on a record has the same area of error, it doesn't matter because the accuracy to the true point is still 5m+. That the area doesn't accumulate to 7m or 10m as data is logged makes no difference because the smallest consistent area is still too large to be useful.

Speed of a bicycle over a given distance or time, where the commonly accepted variance is <5%.

GPS can easily achieve lower than 5% variance in speed average on measures of like-for-like on-road performances, as long as the sampling period is long enough. Again, I'm not arguing that instantaneous velocity is good (the potential inaccuracy for that can be incredibly extreme, especially if you want low latency and when speeds are changing).
There are some phenomena that can cause junk data (such as janky LoS to satellites), but this is mostly detectable.

Originally Posted by Mark McM

That's not really true, either. Moment-to-moment GPS accuracy is also influenced by the number of satellites presently visible, the satellite position (the satellites will be in different positions at different points of time), and also on anything that might momentary block GPS reception (such as tree cover or even clouds). Some GPS receivers will also display the current uncertainty of position measurement, and this value can be seen continuously changing during a journey.

I'm not arguing that GPS positional accuracy is completely invariant to everything, just that it doesn't drift with respect to sample period.

[PJN]

For roll down testing and other close range testing it wouldn’t be to hard for someone to rig Jan up with a differential/rtk gps system and a power meter to come up with some relatively precise AND accurate measurements and devise a test plan to make sure things are repeatable.

I don’t think he cares to build that system at all.

[ripvanrando]

Originally Posted by HTupolev

Sort of, depends on the context. GPS is typically very poor for instantaneous speed, but since it can provide an absolute position reference with basically zero vulnerability to drift, it can produce very good average speed across a large time interval.

You can get the best of both worlds by combining GPS data with something like a wheel sensor.

He often makes conclusions based on peak, instantaneous speed. Single runs. Different gear on different days with claims winds and conditions were the same. I have NEVER found conditions to be identical day to day. Barometric pressure, temperature, humidity, and certainly winds in the 3-5 mph are very difficult to detect and since all winds are local, one cannot presume they had no effect. I do not trust a peak speed reading off an iPhone to claim fenders are faster even with the ridiculously contrived elephant's trunk-like extension....seriously, who rides with another fender bonded on. But he is above questioning. Why should he take questions when the gullible buy his story.

[Mark McM]

Originally Posted by HTupolev

I'm not arguing that GPS positional accuracy is completely invariant to everything, just that it doesn't drift with respect to sample period.

Absolute positional accuracy doesn't vary with speed, but that also means that speed measurement error does vary with speed. GPS speed is calculated by measuring distance traveled (change in position) over some time period. Which means the smaller the distance travelled between measurement intervals, the higher the relative error. GPS may provide adequate measurement accuracy for high speed travel, but not for low speed travel such as with bicycles.

[benb]

Originally Posted by PJN

Do these gravel courses have tight crit like corners? I doubt it but if they did I bet everyone would be hyped on some corner knobs. You know sorta like a cycle cross course. There is a time for file treads and a time for tight knobs and a time for mud tires. If the courses are mostly straight or non crit corners and pretty packed out then big tires at the right pressure probably do ok.

I went and looked at this course that Jan is talking about and it's mostly straight roads.

I think it's kind of a course selection where the tires might not matter. 100 miles of mostly dead straight with 90 degree midwest corners spaced out miles apart. Not enough cornering to matter versus fitness and nutrition and who had a good day or got a good draft or whatever.

Hard to count but it looks like 60-70 corners over 100 miles. Which is overall very very low. There are places with hundreds of corners in 10 miles when you're in the mountains.

Overall I suspect Jan is right. I've rode the various tires and the side knobs on gravel tires don't really seem to do much. I've only really felt them work when the bike already had started to slide. Maybe they saved me from a crash but they wouldn't have let me actually go faster.

I think realistically outside of crits or cases where riders just make bad cornering decisions and crash there are few road/gravel situations where slightly better cornering speed matters a whole lot. And certainly not in races that are 99% straight line.

I'd also suspect that right up to the highest levels rider cornering skill is going to be the differentiator before the tire if the course actually has enough cornering for it to matter. Watching elites it's always seemed like the skill differences have always been larger than tire differences.

Go to downhill MTB regimes where the overall importance of cornering is very high and the average skill level of all the riders with respect to cornering is extremely high and the tire choice starts making a much bigger difference.

[fourflys]

Originally Posted by ripvanrando

But he is above questioning. Why should he take questions when the gullible buy his story.

wow, he's not just living in your head rent-free, pretty sure he's turned into a developer and started expanding..

[tomato coupe]

Originally Posted by fourflys

wow, he's not just living in your head rent-free, pretty sure he's turned into a developer and started expanding..

The guy makes two posts in this thread during a 48+ hour span, and somehow that means JH is living in his head?

[fourflys]

Originally Posted by tomato coupe

The guy makes two posts in this thread during a 48+ hour span, and somehow that means JH is living in his head?

not just this thread, if I remember right.. or it could have been you I was thinking of..

[oldpotatoe]

For HTupolev-

OK, this has to be one of the biggest thread drifts ever..I apologize in advance.

I sent a PM to you but never got an answer..

"Tupolev"..one of the great Soviet Era aircraft designers..any relation?

[lavi]

End of the day, what did the racers ride?

I mentioned earlier that Ted King favors slicks. Brennan Wertz feels the same. Yes, this is on Jan's blog. However, these cats would not, on purpose, put themselves on inferior equipment just for the sake of free tires.

I love playing around with different tire setups on my bikes. I think the tires I have put the most miles on last year probably were the 32 mm Stampede Pass with the Extralight casing. I absolutely love the way they roll, corner, and accelerate. I also find them extremely durable and resilient, despite their low weight, minimal rolling resistance, and wonderfully supple ride quality.

When riding or racing on gravel, I personally love using the slicks. While there is no better feeling than a Hurricane Ridge hooking into some moist hero dirt, there is something special about the way a supple, high volume, slick tire handles on dirt surfaces. The traction always impresses me, even on the loosest of surfaces. If I had to only ride one tire for the rest of my life, it would undoubtably be the 44 mm Snoqualmie Pass with the Endurance casing. With that tire, I can go just about anywhere.

When it comes to choosing tires for pure racing, I will opt for the knobbies if I know the course is going to be particularly muddy or technical. If it’s a fast rolling course like SBT GRVL, BWR San Diego, or The Mid South, then I will opt for a slick tire. The reasons for choosing a knobby over a slick are usually better traction and increased puncture protection. Due to the speeds we often race at, the fact that visibility is quite limited when riding in a large group, and the increasingly technical nature of the courses, I often race on either Endurance or Endurance Plus casings. When training or doing a longer adventure ride, then I usually ride Endurance or Extralight.

And, not that it matters in the least, but I agree that the RH 32s are pretty much the perfect tire (for me). I don't feel I'm really giving up much, if any, "performance" (as if I really care anyhow) with a 32 over a 28. For me, 28s on my pure road bikes. 32s on everything else, unless the roads are crap and I need even more tire. Then, 35s.


I follow Ted on IG. After his most recent Hawaii trip, I messaged him regarding tires. Here's that convo:

From me: Anyhow, question is: do you always ride 32/35 tires? From your HI riding, it looked like some 35s on there. Are you 100% tubeless?

From Tedly: Yes, safe bet that on road bikes I'm 32-35. Then on gravel I run as narrow as a 38 and can fit up to 48 in there.

Pretty sure Ted likes to go fast...whenever and wherever he can. RH makes 26 and 28s. Ted starts with a 32 and goes from there. That says something (to me).

[spoonrobot]

Ted King (P27 Midsouth 2023) and Brennan Wertz are essentially field fillers for domestic P1 gravel. I think the Shasta race in the blog post is the only race Wertz has won in a while.

What are the winners riding?

[lavi]

Originally Posted by spoonrobot

Ted King (P27 Midsouth 2023) and Brennan Wertz are essentially field fillers for domestic P1 gravel. I think the Shasta race in the blog post is the only race Wertz has won in a while.

What are the winners riding?

Pretty sure Keegan runs file tread....which is basically a slick.

I ain't arguing. I'm just reporting what these cats ride as it's salient to a thread on RH tires. I don't give a rat's ass about what others are riding. This is about RH tires...to knob or not.

[spoonrobot]

Slicks are pretty crap for gravel, especially if they're single compound rubber (like Rene Herse tires). It's why almost every racer is on semis with multi-compounds and side knobs.

[callmeishmael]

I always think it's risky examining pro equipment choices for racing and then extrapolating to assume they're optimal for recreational amateur use.

[spoonrobot]

Originally Posted by callmeishmael

I always think it's risky examining pro equipment choices for racing and then extrapolating to assume they're optimal for recreational amateur use.

This was Bicycle Quarterly's stance until about 2019. Now it's about dollar bills.

We can roll with it, especially because it's such a rich dunk on one of the core tenants. Nobody ever found success riding huge tires relative to the rest of the field anytime or anywhere. But since gravel is on "big tires" it made a convenient end run around that fact. So now we're supposed to be blown away that people win races on 38s or 40s against other riders on 38s or 40s.

Get at me when someone starts crushing the field at a Lifetime event on a beach racer with 60mm tires (which tested as fast as anything else).