New Continental 5000S Tires - Tubeless Compatible

[RocketRacing]

Add an estimated 2.5w reduction for higher tire pressures (90psi to 110-120) ... not insignificant for a lightweight rider like me.

Then you are hit with 20 watts disadvantage once the road turn rough compare to lower pressure tires.
People keep omitting suspension loss from the equation. I don't know why people, especially light one, keep overinflating tires just to get that little bit saving of of hysteresis loss at cost of hefty increase in suspension loss on non glass-smooth road.

I am aware of those losses, and only go high pressures if my route is appropriate (low speed climbs and high speed flats). But do you have a reference to show the 20w loss? Has it been measured? I am assuming someone has done a smooth vs rough roller test.

I guess it is like the low pressure situation with mountain bikes. It is a tough balance because for every situation where lower pressure helps speed... in others it slows you down. As such i always try to find a happy medium pressure based on where i ride.

It is all a complex equation of aero drag vs rolling resistance (influenced by surface). Hard to know the right answer.

Of interest, my buddy has yet to be able to match times he got on his 25mm tires on his 30mm tires... no matter how hard he tries. He is well over 40km/hr and i am quite sure that the aero losses of wider tires at those speeds are hurting the rolling resistance gains.

[mikemelbrooks]

I am aware of those losses, and only go high pressures if my route is appropriate (low speed climbs and high speed flats). But do you have a reference to show the 20w loss? Has it been measured? I am assuming someone has done a smooth vs rough roller test.

I guess it is like the low pressure situation with mountain bikes. It is a tough balance because for every situation where lower pressure helps speed... in others it slows you down. As such i always try to find a happy medium pressure based on where i ride.

It is all a complex equation of aero drag vs rolling resistance (influenced by surface). Hard to know the right answer.

Of interest, my buddy has yet to be able to match times he got on his 25mm tires on his 30mm tires... no matter how hard he tries. He is well over 40km/hr and i am quite sure that the aero losses of wider tires at those speeds are hurting the rolling resistance gains.

I think the better solution would be to run different width tires and pressures depending on wether the tire is going on the front or the back. Weight balance on a bike with rider is around 45% front and 55% rear, and only the front tire sees clean air. we are used to see bikes with different profile wheels perhaps the marginal gain is a narrower front tire for aero and wider at the back at lower pressure for rolling resistance?

[jcnz]

That's exactly what I'm testing... 25mm on the front with 28mm on the back on a madone slr disc...

Sent from my ALP-L29 using Tapatalk

[AJS914]

https://janheine.wordpress.com/2018/01/ ... the-world/

https://janheine.wordpress.com/2018/05/ ... isnt-easy/

I was reading these blogs the other day and it got me to thinking about what would be the fastest tire/wheel if you could measure hysteric and suspension losses and factor in aerodynamics and pressure.

The blog entry claims that roller tests are inaccurate and favor stiffer tires like the Grand Prix.

I just moved to a place where the roads are rough. They aren't broken up, just chip sealed country roads where you can feel the power draining from your legs. I used to run 95/100psi and now I'm down to 75/80 just to cope with these roads. This is on 23mm GP4000s.

For the first time I'm thinking about a new frame just so I could run maybe 30-32mm wide tires on a wide rim for these roads. I think it would be faster than getting beat up on narrow tires.

[RocketRacing]

I am aware of those losses, and only go high pressures if my route is appropriate (low speed climbs and high speed flats). But do you have a reference to show the 20w loss? Has it been measured? I am assuming someone has done a smooth vs rough roller test.

I guess it is like the low pressure situation with mountain bikes. It is a tough balance because for every situation where lower pressure helps speed... in others it slows you down. As such i always try to find a happy medium pressure based on where i ride.

It is all a complex equation of aero drag vs rolling resistance (influenced by surface). Hard to know the right answer.

Of interest, my buddy has yet to be able to match times he got on his 25mm tires on his 30mm tires... no matter how hard he tries. He is well over 40km/hr and i am quite sure that the aero losses of wider tires at those speeds are hurting the rolling resistance gains.

I think the better solution would be to run different width tires and pressures depending on wether the tire is going on the front or the back. Weight balance on a bike with rider is around 45% front and 55% rear, and only the front tire sees clean air. we are used to see bikes with different profile wheels perhaps the marginal gain is a narrower front tire for aero and wider at the back at lower pressure for rolling resistance?

With his new (to him) aero wheels (25mm width) he will be doing 23cc (25mm measured) front, 25cc rear.

[TobinHatesYou]

The blog entry claims that roller tests are inaccurate and favor stiffer tires like the Grand Prix.

Smooth drum tests present a Goldilocks scenario, but most of the respected testers have uneven drums.

[Dan Gerous]

Maybe not exactly like real roads but better than a smooth drum.

[Hexsense]

Then you are hit with 20 watts disadvantage once the road turn rough compare to lower pressure tires.
People keep omitting suspension loss from the equation. I don't know why people, especially light one, keep overinflating tires just to get that little bit saving of of hysteresis loss at cost of hefty increase in suspension loss on non glass-smooth road.

I am aware of those losses, and only go high pressures if my route is appropriate (low speed climbs and high speed flats). But do you have a reference to show the 20w loss? Has it been measured? I am assuming someone has done a smooth vs rough roller test.

No reference to 20w loss. I am 100% to be wrong.
I just make up a number from the magnitude of possible saving that you quote 2.5 watts, compare to raised up rolling impedence when you over inflate.
See how much steeper the rolling impedence goes up compare to how little slope rolling resistance go down when raise the pressure in article below (mainly coarse asphalt is the realistic road around me, the red line of broken road is also something i ride on a little bit):
https://silca.cc/blogs/journal/part-4b- ... -impedance
Those numbers, both crr and break point pressure, are subject to change depend on weight, tire width, condition, etc. But general idea is there, slightly over inflate is a lot worse than slightly under inflate.

Maybe not exactly like real roads but better than a smooth drum.

Isn't his test put out power by the roller and measure power at the roller?
If tire jump and skip, the measured rolling resistance drop momentary and count as advantage to other tire that deform and stay with the roller?

[AJS914]

I wish the roads I ride on were often that smooth!

Maybe not exactly like real roads but better than a smooth drum.

[TobinHatesYou]

Isn't his test put out power by the roller and measure power at the roller?
If tire jump and skip, the measured rolling resistance drop momentary and count as advantage to other tire that deform and stay with the roller?

Jarno uses 42.5kg loads in his tests. The tire is not going jump or skip.

[bm0p700f]

On the hutchinson fusion 5 TLR tyre packets it says the ideal pressure for a 70kg rider is 99 psi! FrenCh roads are smoother than U.K roads though.

[RocketRacing]

https://silca.cc/blogs/journal/part-4b- ... -impedance

thank you for this link!!! Classic internet: most of it is crap, but there is a handfull of usefull stuff out there if you know where to look.

My only opinion there is that looking at his data, you need to get into pretty obscene pressures before too high of a pressure starts to hurt. If the roads are often crap, i am taking my low pressure, wide tired, tubless cx bike... or my xc bike... or my fat bike. It all depends on the route. Each has it’s “sweet spot. “

And it is kind of like an aero/narrow vs low rr/wide/poor aero choice... the right answer kind of depends on your speed.

The impedance issue complicates it all further. You need to balance aero, rr, and impedance... and based on your speed/terrain, there is no one correct answer... except that maybe very wide tires, with aero wheels sized appropriate (disc brakes!!!) is the all round “closest” answer (i did not say “best”) for most situations. But a narrow 23cc tire may still be the fastest option on a smooth road, or a fat bike tire under 5psi may still be best for a very rooty path.

It is all a reminder that it is less about “more being better” and more about “the best tool for the job.”

[micky]

On the hutchinson fusion 5 TLR tyre packets it says the ideal pressure for a 70kg rider is 99 psi! FrenCh roads are smoother than U.K roads though.

Do they mention tyre windth?

[RocketRacing]

This all reminds me of the comment i made to a local lbs owner. He had a new on-trend gravel bike. He fit it with 2.3inch 29ers. I said it was a front fork away from a mountain bike from 10 years ago.

I will leave everyone here with the future of bikes:

[Dan Gerous]

On the hutchinson fusion 5 TLR tyre packets it says the ideal pressure for a 70kg rider is 99 psi! FrenCh roads are smoother than U.K roads though.

The only thing more wrong than tire companies' width numbers is their pressure recommendations.