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Re: Tire Pressure Poll [s13tx] [ In reply to ]
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How many coats of glue does he apply?

Does he apply it around the entire rim?
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Re: Tire Pressure Poll [natethomas] [ In reply to ]
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100 on my tri bike.

About 75 on the gravel bike.
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Re: Tire Pressure Poll [Slowman] [ In reply to ]
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It's important to note that WheelEnergy and BicycleRollingResistace (as well as all of the other Crr machines/methods I've ever seen) are designed to specifically isolate tire losses due to hysteresis, or what we refer to as 'casing losses' and are NOT designed to pick up on any of the impedance losses seen when riding on the road. This makes sense as when you are designing a tire, you are only worried about what you can control through tire design and manufacturing, and everything else is just complicating noise.

The impedance part of the equation comes from testing with actual high hysteresis/high damping masses (humans) sitting imperfectly on actual bicycles riding on various surfaces. The impedance losses are always there, but are continually rising as pressure increases.. at some point they overcome the casing losses of the tire, as the bulk of the Crr moves from losses due to casing to losses due to shaking the high hysteresis mass on top of the bicycle.

Personally I think we need to reframe this post and so many others.. without knowing the MEASURED tire width, rider weight, and road surface it is impossible to have an opinion here.. so if somebody says they ride 120psi, we need to know way more before we say that it too much or too little.

Lastly, we are ~90% done with our pressure algorithm based on fitting thousands of real world test data points and look forward to sharing once the calculator is ready for prime-time. I think for many, the amount of information required on the input side will be surprising, but that's a good thing.

Josh

http://www.SILCA.cc
Check out my podcast, inside stories from more than 20 years of product and tech innovation from inside the Pro Peloton and Pro Triathlon worlds!
http://www.marginalgainspodcast.cc
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Re: Tire Pressure Poll [SBRmd] [ In reply to ]
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SBRmd wrote:
JMike wrote:
Why is tire pressure always addressed as 'run' or 'ran'?


Everyone here says they are “running” this or that for anything. Can’t stand that.

If it's something some people might consider outlandish you don't just "run" it. You "rock" it:

"I was rocking disk wheels front and back"

[A few years ago - but no longer]: "Rocking disk brakes."

"Rockin' the speedo!"


http://www.jt10000.com/
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Re: Tire Pressure Poll [joshatsilca] [ In reply to ]
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joshatsilca wrote:

Personally I think we need to reframe this post and so many others.. without knowing the MEASURED tire width, rider weight, and road surface it is impossible to have an opinion here.. so if somebody says they ride 120psi, we need to know way more before we say that it too much or too little.
Josh


Glad someone else is making sense in this thread.
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Re: Tire Pressure Poll [joshatsilca] [ In reply to ]
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joshatsilca wrote:
...without knowing the MEASURED tire width, rider weight, and road surface it is impossible to have an opinion here..

AMEN!

This is such a simple concept but so poorly understood by so many. The wide variety of rim widths around these days has definitely complicated the situation and made most tire pressure charts worthless, hence the need for MEASURED tire width rather than the tire width printed on the sidewall.

I know a woman who recently had a nice custom steel frame made for her. Her new wheels had 25mm tires mounted on wide rims with an internal width of 21.5 mm. She thought 110 psi was just what you used for all road tires, and the harsh ride was a byproduct of the steel frame. After I set her straight, suddenly her new bike got a much nicer ride!
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Re: Tire Pressure Poll [joshatsilca] [ In reply to ]
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joshatsilca wrote:
It's important to note that WheelEnergy and BicycleRollingResistace (as well as all of the other Crr machines/methods I've ever seen) are designed to specifically isolate tire losses due to hysteresis, or what we refer to as 'casing losses' and are NOT designed to pick up on any of the impedance losses seen when riding on the road. This makes sense as when you are designing a tire, you are only worried about what you can control through tire design and manufacturing, and everything else is just complicating noise.

The impedance part of the equation comes from testing with actual high hysteresis/high damping masses (humans) sitting imperfectly on actual bicycles riding on various surfaces. The impedance losses are always there, but are continually rising as pressure increases.. at some point they overcome the casing losses of the tire, as the bulk of the Crr moves from losses due to casing to losses due to shaking the high hysteresis mass on top of the bicycle.

Personally I think we need to reframe this post and so many others.. without knowing the MEASURED tire width, rider weight, and road surface it is impossible to have an opinion here.. so if somebody says they ride 120psi, we need to know way more before we say that it too much or too little.

Lastly, we are ~90% done with our pressure algorithm based on fitting thousands of real world test data points and look forward to sharing once the calculator is ready for prime-time. I think for many, the amount of information required on the input side will be surprising, but that's a good thing.

Josh


Josh thats awesome your are making a "pressure algorithm" ....... In the end I think I have this figured out better then most so will probably minimize the small gap I have on the masses, but will be very nice to have especially if switching btw different tires. Cant wait to see it when its done, thank you.

2024: Bevoman, Galveston, Alcatraz, Marble Falls, Santa Cruz
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Re: Tire Pressure Poll [tttiltheend] [ In reply to ]
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tttiltheend wrote:
The wide variety of rim widths around these days has definitely complicated the situation and made most tire pressure charts worthless

Rim profiles have never been constant, tire width labeling has never been consistent, and manufacturer tire pressure charts have always varied wildly in methodology and rarely been very useful.
Last edited by: HTupolev: Sep 24, 19 9:47
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Re: Tire Pressure Poll [joshatsilca] [ In reply to ]
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Running Vittoria Cora EVO CX in 700 X 23mm Tubular on old Zipp 404 rims. Weight is 155 lbs. I've been running 100 psi. Do you think I should drop the pressure down to 95 or 90 psi?
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Re: Tire Pressure Poll [Herbie Hancock] [ In reply to ]
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Herbie Hancock wrote:
Running Vittoria Cora EVO CX in 700 X 23mm Tubular on old Zipp 404 rims. Weight is 155 lbs. I've been running 100 psi. Do you think I should drop the pressure down to 95 or 90 psi?

Have you not grasped the point yet that the only person that can answer that question is you!!!

Only you know the roads you ride on, only you know the way you like to ride the bike, only you know the compromises you are willing to live with.

Listen less to the experts (no seriously that's a joke) on here and test and try things out for yourself on the courses that you ride.

I run anything from 7 psi to 120psi depending on lots of factors.

Go find out for yourself what's best for you.
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Re: Tire Pressure Poll [Mario S] [ In reply to ]
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Thanks Mario but no time for testing. I barely have enough time to train and drink beer. Will drop to 95 psi and see what happens.
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Re: Tire Pressure Poll [Herbie Hancock] [ In reply to ]
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Herbie Hancock wrote:
Thanks Mario but no time for testing. I barely have enough time to train and drink beer. Will drop to 95 psi and see what happens.

That's how you do it - small adjustments, see how it goes. I think the larger thing he was getting at is that - even if you provide an insane amount of detail to the forum about your exact setup, weight, picture of the surfaces you ride on, power meter data, etc... it's still going to be tough for us to give you a perfect answer.

The take-home from our many home page articles on this topic, along with the Tubeless Super Thread is that, when in doubt, err on the lower side with pressure. You're dropping by 5psi... that's a reasonable move. If you start striking the rim on the pavement a bunch and risking rim damage, that would tell you to raise the pressure back up. If it doesn't feel like anything changed, you might try dropping it a bit more. It's that simple. The only absolute here is that you shouldn't be running more than ~120psi under pretty much any circumstance.

I get a lot of questions about this and people want a perfect answer, but the reality is that you just have to try it for yourself. The only real way to know the exact perfect pressure for a specific piece of road is to get a power meter and do your own controlled testing at different pressures.
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Re: Tire Pressure Poll [joshatsilca] [ In reply to ]
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After reading this thread I plan on switching from 120 psi on (both tires) to 95 on Front and 100 Rear for "new" (read wide) zipps.
My question is should I try these same pressures on my "older" (read narrower) Reynolds strike winter wheels. I weigh a whooping 195lbs (read I need to put the cookie down, lol) ty
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Re: Tire Pressure Poll [bikeenvy] [ In reply to ]
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How wide are your tires?
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Re: Tire Pressure Poll [jimatbeyond] [ In reply to ]
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25's
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Re: Tire Pressure Poll [bikeenvy] [ In reply to ]
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What width do they measure when mounted on your wheels?
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Re: Tire Pressure Poll [bikeenvy] [ In reply to ]
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bikeenvy wrote:
Reynolds strike winter wheels.

You have to laugh!
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Re: Tire Pressure Poll [RowToTri] [ In reply to ]
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RowToTri wrote:
Interesting - they seem to be in the lower pressure camp. I posted this in another thread but maybe I should have posted it here:

Some of the information out there on tire pressures seems to be conflicting.

Here is Roval's recommendation (I run a Roval CLX 64 front wheel)


Here is HED's recommendation (I run a Jet Disc Plus on the rear)


My 23c GP5000 tire measure 26mm at 85 psi on my front wheel. Roval does not say if it's chart is for measured or labeled tire widths, but it would recommend >107psi if labeled, 89 if measured. HED's chart is for labeled width so they recommend 72 psi. Quite a huge difference! What is one to do? They cannot both be right.

On the rear, I've been running a 23C GPTT which actually measures 27.75mm on my HED Jet Disc Plus! I'm re-thinking that tire right now, given the 25mm brake track on that wheel, but the aerocoach testing puts it ahead of the GP5000 on their wheel - need to get the width of that wheel. At least in the back it's shrouded.



From Silca's website, I cannot find a chart with enough data to really select a pressure given tire width and rider weight, but there is this, which seems to suggest even higher pressures than roval, but we do not know rider weight:


Here's a chart from Flo (They apparently got it from TomA) which I'm pretty certain refers to measured width and recommends about the same as roval, ~90.


My inclination is to go with the Flo(TomA)/Roval recommendations since they agree, and Tom does a solid job in this testing.

Is there a better source that I am missing?

My race wheels are Bontetrager Aeolus70's. Tires sit "wide" in there, so they look like they are 25's vs 23's. I am 145 lbs and go with 80-90 psi based on road surface. In training I have 28mm Vittoria Corsa CX and I go with 60-65psi. I may put 70psi if I am training in Tremblant where the road surface is near perfect
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Re: Tire Pressure Poll [devashish_paul] [ In reply to ]
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HED wheels have been winning world championships for decades so I give their charts the nod.

I'm ~150 lb. and run a FLO 60 front, GP4k II 23c, latex at 75psi and a HED Jet+ Black Disc rear, GP4k II 23c, latex at 75psi.

Looking forward to Silca's calculator! I assume I'm right in the ballpark after listening to his podcasts.

-------------------
Madison photographer Timothy Hughes | Instagram
Last edited by: Timtek: Sep 29, 19 7:17
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