Quite a bit higher! Also not sure about the Wood Track recommendation. That is pretty Niche though.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

Ditto... a boatload higher than I expected. My "Mild Pavement" recommendation is 101 PSI on a 25mm tire.

15 psi higher than I thought he would recommend. 100 psi for my fat ass is more than the rated pressure for my 7.8's.

Doesn't work... Keeps telling me to fill out the form info to use the calculator. Then nothing happens... I just see the same form again.

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What's your CdA?

Yeah its a bit glitchy. I just refreshed the page after a few minutes and it worked.

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Benjamin Deal - Professional - Instagram - TriRig - Lodi Cyclery
Deals on Wheels - Results, schedule, videos, sponsors

I took "lbs" off weight and it worked

Yes, same here. Basically in the 99 to 100 psi on the 25mm tires. Weird that it does not differentiate between latex, tubeless, etc setups.

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Next races on the schedule: none at the moment

I was at IM Florida a few weeks back helping some people pump up their tires after I was done since I had a pump. Every single European told me they wanted at least 120psi and I probably helped 6 or 7 people. One guy asked me if I was sure I wanted to pump my tires only to 100psi. I started second guessing myself but I held to my 100 tho.

Are people using the actual measured tire width or the stated tire size? It says measured, which you can pretty much add 2mm to the stated size if you don’t have calipers.

My complaint is there’s no rough & smooth chipseal option. That’s got to be somewhere between old asphalt and cobbles. Also surprised to see lower pressure recommended for smooth gravel than cobbles.

Those variables shouldn't effect tire pressure choices (except maybe cobble for tubed setups if you are at risk of bottoming


Second---be sure you are using actual measured width on your wheels as measured with calipers. My 23mm on Roval is like 27mm actual

Cobbles are a different beast. Can be bigger hits but lower frequency. "Smooth Gravel" is probably not dirt, more like heavy cinder/ small pebbles. Much higher frequency of deformation.

Hopefully Josh can chime in, because this is not really lining up with his previous recommendations or my experience.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

My real world experiences aren't lining up with the calcuations either.

The calculator is putting me 10-15 Psi high on my road setup and 5-8 Psi low on my gravel setup(s)

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In what way does it not line up with your experience?

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

The calculator has me up around 100psi on conti 23s (yes, I even used 25mm in the calculator), and the ride is quite uncomfortable and a bit jarring that high. My by feel pressure for comfort, cornering, and flat protection is 80-85 psi.

My usual gravel tire setup is 650x42 and he calculator has me in the 25psi range. There would be too much squirm at this pressure and definitely a high risk of flatting. My usual pressure is around 30 -32 psi for my 42mm setup.

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On the 7.8's website they recommend pressured up to 115 psi (23mm and 250 lbs) and the wheel manual says 125psi is the max. Where are you seeing a 100 psi limit?

Looks like I am wrong. Not sure why I thought they were maxed out at 87 psi? I will take another look at my manual, but online it definitely says they can go much higher

Well, Josh is like the world's expert on bike tire pressure and he has tons of real measured data of different tires, wheels road surfaces, riders... I would trust that a lot more than personal feel, assuming you fill it all out correctly. I use gp5000 23c tires but they measure 26mm on my wheels. Hardest thing to know is exactly what he means by "mild asphalt" etc...

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Ed O'Malley
www.VeloVetta.com
Founder of VeloVetta Cycling Shoes
Instagram • Facebook

I am with you, Sean. I'd like to have guesses at more 'real world' types of surfaces and mixes. How about really narrowing it down to 50% old asphalt/50% chip-seal and other choices like that so we can really make more informed 'guesses'. I don't think I have any cobblestone races coming up...And while I'm whining like a biatch, how about adjustments for dry/light rain/heavy rain.

And everyone should use measured widths-come on really? Do people not own a paper clip and a ruler??


For the record, it's about 5-10 psi higher than what I currently use, and I'm also a bit surprised by that.

If you listen to Josh’s podcast, he has detailed how to set your tire pressure by feel for road. He basically says you keeping going lower until you get squirm in the corners or others negative handling trails, and go up a bit from there. I have verified my road pressure with Josh’s ‘by feel’ method.

No need to go into detail on the gravel pressure side of things, but if the terrain you ride and the way you ride requires a certain pressure not to flat, and you don’t want to use more volume for various reasons, then you get a pretty damn good feel for off pavement pressure.

I’m sure Josh would agree, the calculator is giving you a good starting place and it’s up to the user to adjust up and down from there based on their actual conditions, speed of riding, and riding style.

For me I was just surprised the numbers were quite far from the pressures I’ve concluded to work best for me.

Edit: I forgot to mention, I am a Josh/Silca fanboy 😃

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The numbers suggested for me were about spot on from what i use. The zipp tyrewiz app suggests a bit lower.

Edit: I read this backwards.

Yeah, bizarre.

I find it lower, but pretty much in line with what I previously evaluated from the "V shape" graph presented previously on their blog, for same tyre, wheel size and weight, on medium quality road.

From "V shape" graph ("official 25mm" GP4000sII on 17mm wheel - so probably wider - if I remember well ?) : optimal around 95 PSI

From calculator (based on 27mm measured "official 25mm" GP4000sII on 17mm wheels) : 86/87 PSI

From the french side :

With cobbles, lower pressure is better (speed wise), but the problem is : you broke wheels. Or you need to have a really large tyre.
If tyre deformation is smaller than cobbles "height deviation", with low pressure you broke the wheel.

This will not happen with smooth gravel, so you can really adjust the pressure lower for speed, not dealing with rim destruction risk.

See the "cobble" graph here : https://blog.silca.cc/...ressure-optimization

There is clear indication that a lower pressure will be better for speed.... but....

This is the reason for suspended bikes on Paris-Roubaix : increase flexibility to deal with cobbles "height deviation" above tyre deflection.

Maybe this is the statement we all seem to be missing:

“Surface Type: We recommend optimizing for the worst surface you are riding as you are generally better to be a bit low than to be a bit high.”

Although we generally have good roads around here, they vary from new to sometimes “smooth” chip seal. I have found the old pavement pressures line up pretty close to what I run on a daily basis.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook