SILCA optimal tire pressure calculator

[SlowPokePete]

Pass.

Would've done it if not for the email nonsense.

Just the calculator please...

SPP

[Duende]

Ok... sounds like for the majority of folks here it's giving higher pressures than what they're running.

I'm not completely crazy. Good to know!

[Louis]

It takes about 30 seconds to set up a perfectly legitimate Gmail account where you can use any name you want, Jimmy Hoffa, Lance Armstrong, whatever, and whenever you're in a situation like the Silca request for e-mail you just use that.

[R3awak3n]

Originally Posted by Duende

Ok... sounds like for the majority of folks here it's giving higher pressures than what they're running.

I'm not completely crazy. Good to know!

Its giving me lower than I normally run, not a lot but a bit lower.

[AngryScientist]

i really like silca, and i appreciate some of the things they are doing for cycling, and some of the products they make, but some stuff, IMO, just misses the mark, or the big picture.

this "optimal" tire pressure calculator is a good example.

i think the big picture is that everyone is different, and trying to distill an "optimal" tire pressure down to the tenth of a psi through a handful of questions is ridiculous.

[fa63]

Originally Posted by R3awak3n

Its giving me lower than I normally run, not a lot but a bit lower.

Same for me.

[fa63]

Originally Posted by AngryScientist

i really like silca, and i appreciate some of the things they are doing for cycling, and some of the products they make, but some stuff, IMO, just misses the mark, or the big picture.

this "optimal" tire pressure calculator is a good example.

i think the big picture is that everyone is different, and trying to distill an "optimal" tire pressure down to the tenth of a psi through a handful of questions is ridiculous.

While I don't necessarily disagree with what you are saying, I also think it is possible that there exists an optimal tire pressure which balances rolling resistance and comfort. People can still ride what they prefer, but it is not bad to have a point of reference. Not saying this is what Silca have achieved here, but Josh Poertner probably has tons of data on this, and I assume smart people on his staff to analyze the data intelligently.

[jpritchet74]

I was shocked to see the high pressures that it gave me - about 8-10 psi higher than what I have been running.

[bikinchris]

I have used the Berto tire pressure calculator and find it to be fine.

[joshatsilca]

Originally Posted by AngryScientist

i really like silca, and i appreciate some of the things they are doing for cycling, and some of the products they make, but some stuff, IMO, just misses the mark, or the big picture.

this "optimal" tire pressure calculator is a good example.

i think the big picture is that everyone is different, and trying to distill an "optimal" tire pressure down to the tenth of a psi through a handful of questions is ridiculous.

Couple of points to make here as it seems we have some mis-interpretations of what this is.. at the moment it is exactly what we say it is, it is the creation of an algorithm to curve fit more than 4000 pro tire pressures which have each been optimized for speed, not comfort. These points were all determined using Chung method type protocols with real pros and if you are savvy, you can find Fabian's Olympic Gold, 7 of the last 10 Roubaix winning pressures, numerous men's and women's Dirty Kanza winners, etc.. it's all in there.

It is also the beginnings of the discussion which we really need to be having about tire size, which is measured size and not sidewall size.

Unfortunately we had to strip out some of the adjacent content that was originally loaded in the calendar due to the site crashing as it was overwhelmed with traffic on the first day.. and that content is going back live now. But.. I think that many of the people finding road tires to read high and gravel to be too low are probably closer than they think when looking at measured tire size. Modern, wide road rims have our road tires running quite a bit wider than sidewall says, while most gravel tires have casings there are narrower than sidewall as the sidewall 'width' is measured at the knobs to help with frame clearance. So a '23mm' GP4000 on an ENVE 4.5AR measures 28.9mm wide, while a 29x2.25" (57mm) WTB Riddler on that same rim (25mm internal) measures 51mm at the casing.. so these would be 29mm and 51mm in the calculator.

We will be building this out further with additional features like a tire casing size estimator (enter your tire and rim and get the measured width) as well as a pinch flat risk calculator and some other things that people want/need.

Remember, you are all on the internet immersed in this stuff every day, but 98% of the rest of the world isn't and is instead asking to put 125psi in their 28mm tires that measure 30mm on their fancy carbon wheels at Gran Fondo events.. I even have a lot of bike shops finally coming around on pressures and while we have our pro teams measuring and calculating, almost nobody else is.. and the difference can be a few ceramic bearing upgrades worth of watts if you do it wrong.

Also, these are pro pressures.. they are going faster than the rest of us and tire pressure is speed sensitive due to the hysteresis in the tire/tube. So as you go faster, the breakpoint pressure increases slightly as the tire is able to absorb larger bumps with less rider jostling. Think of the difference between riding cobbles fast vs slow or hitting a speed bump in your car fast vs slow.. the effect here isn't massive, but as a non-pro I'd recommend taking these numbers as the starting point and dropping a few as you see fit..that is another part of the calculator coming in future version..

Lastly, the Berto charts are interesting and can provide a good starting point, but for any type of aggressive cycling, you cannot use the front pressures based on static/flat weight distribution. Particularly for Pro cyclists who are already running lower/longer positions, these lower front pressures can be dangerous while descending as the rider weight distribution shifts even further forward due to road slope and due to aggressive aero positioning. We allow at most 2-3% lower front pressure for any sort of hilly event and run them at 50/50 type pressure balance on mountain stages as weight distribution can be more like 55/45 front biased on mountain descents.

Josh

[jpritchet74]

Thanks for the response Josh!

[false_Aest]

hmm. i think its might be broken.

i keep getting told to submit information but when i do it asks me to submit information again.

[jwalther]

Originally Posted by false_Aest

hmm. i think its might be broken.

i keep getting told to submit information but when i do it asks me to submit information again.

Same here.

[jpritchet74]

Just tried it again and it's working for me.

[marciero]

Originally Posted by AngryScientist

i really like silca, and i appreciate some of the things they are doing for cycling, and some of the products they make, but some stuff, IMO, just misses the mark, or the big picture.

this "optimal" tire pressure calculator is a good example.

i think the big picture is that everyone is different, and trying to distill an "optimal" tire pressure down to the tenth of a psi through a handful of questions is ridiculous.

I think so. We can't even measure pressure that accurately, though it's not as bad as measuring spoke tension.