Compass Bon Jon Pass: one of the 5 fastest tires tested by Tour magazine

[fiamme red]

https://janheine.wordpress.com/2018/01/31/one-of-the-5-fastest-tire-in-the-world/

Very impressive, a 35 mm tire among 23-26 mm tires!

http://www.tour-magazin.de/uploads/tx_saltnews/32/32ce49c6be2506e5eabc1c6d55e8af39cbd41fba.jpeg

[spoonrobot]

Interesting that the resistance for it is so much higher on the rough asphalt. I assume that's due to being overpressure compared to the narrower tires.

[echappist]

pretty useless data. width and pressure not kept constant throughout...

[Mark McM]

pretty useless data. width and pressure not kept constant throughout...

No, that actually makes it more useful. This tires in this test ranged in width from 23mm to 35mm, and there is no reason to use the same pressure in a 23mm tire as a 35mm tire. Instead, proper tire pressure should vary roughly to the inverse of width. So for a test of practical usage, wider tires should be run at lower pressures than narrower tires.

Many tests have shown that at the same pressure, wider tires have lower rolling resistance than narrower tires. But for practical applications, this has little meaning, because wider tires shouldn't be run at the same pressure as narrower tires. When rolling resistance is tested under a range of different pressures, it has been shown that when the pressure is inverse to width, rolling resistance of otherwise similar is nearly identical*.

Here are graphs of the rolling resistance of the same model of tire (Continental GP4000s II) in 4 different widths over a range of pressures:

http://www.slowtwitch.com/articles/images/1/82121-largest_1_4000S_Crr_chart.png

As noted, at the same pressure (the vertical yellow line), the wider tires have the lower rolling resistance. But also note an equal rolling resistance (the horizontal yellow line) occurs at pressures that are roughly inverse to the tire widths.


* For hysteresis losses in the tire. Rolling losses due to vibration (sometimes also known as suspension losses), follows different relationships, and is usually lower for wider tires.

[Mark McM]

Interesting that the resistance for it is so much higher on the rough asphalt. I assume that's due to being overpressure compared to the narrower tires.

That's probably true. 6 Bar is excessive for a 35mm tire. Lowering the pressure to a more practical level, while probably increasing rolling resistance on flat surfaces a bit, would probably also reduce rolling resistance on rough surfaces by a large amount.

It should also be noted that the 3 lowest rolling resistance tires in this test are ultra-light weight race tires, designed specifically for minimum rolling resistance and not durability. These tires would not last very long in the conditions the Bon Jon Pass tires was meant for.

Still and all, this data does show that a wide (35mm) tire can be nearly competitive to specialist racing tires, even on smooth roads.

(I'll just add the comment that calling the Jon Bon Pass "One of the 5 fast tires" is a bit of hyperbole. The other 4 tires in the test are certainly among the best, but there are a number of other top tires not included in the test that are also very good, and including these tires would likely push the Jon Bon Pass out of the top 5. But this isn't really a criticism of the Jon Bon Pass, as these other tire tires were designed primarily for low rolling resistance, and are not as good as the Jon Bon Pass in many other qualities.)

[beeatnik]

100psi for a 25mm Conti 4000s II on the Mean Streets of LA would be barbaric. 70 to 80 is more civilized.

They're fat tires!
https://farm4.staticflickr.com/3669/33725493025_3d6d7b724c_b.jpg

[Mzilliox]

wait, so their 35mm tire is faster than the 32 or 28? really?

hmmm:bike:

[moobikes]

I would think it makes more sense to put the Compass tires in the same classification as the other built-for-speed tires, because that's what the Compass tires are, especially the EL ones. They have thicker treads for longer life and durability but the minimalist sidewalls and lack of puncture resistant belt are a clear indication they are made to minimize RR.

All the other fast general road use tires available today from the other major brands all have much thicker sidewalls, and puncture resistant belts. It is no surprise the Compass tires rank highly against them even though they are so fat.

[beeatnik]

wait, so their 35mm tire is faster than the 32 or 28? really?

hmmm:bike:


Not exactly. Fast means rolling resistance and aero

[moobikes]

Why would you use a 35mm tire if you needed aero-ness?
On crap roads the 35mm Compass is faster than a 25mm Conti, which is the entire point of the Compass fat tires.
If Conti made a 35mm GP4000sii it will likely still be slower than the Compass because of design and construction difference.

[ergott]

No way I'd ride a 35mm tire at 87psi.

[echappist]

No, that actually makes it more useful. This tires in this test ranged in width from 23mm to 35mm, and there is no reason to use the same pressure in a 23mm tire as a 35mm tire. Instead, proper tire pressure should vary roughly to the inverse of width. So for a test of practical usage, wider tires should be run at lower pressures than narrower tires.

Many tests have shown that at the same pressure, wider tires have lower rolling resistance than narrower tires. But for practical applications, this has little meaning, because wider tires shouldn't be run at the same pressure as narrower tires. When rolling resistance is tested under a range of different pressures, it has been shown that when the pressure is inverse to width, rolling resistance of otherwise similar is nearly identical*.

Here are graphs of the rolling resistance of the same model of tire (Continental GP4000s II) in 4 different widths over a range of pressures:

http://www.slowtwitch.com/articles/images/1/82121-largest_1_4000S_Crr_chart.png

As noted, at the same pressure (the vertical yellow line), the wider tires have the lower rolling resistance. But also note an equal rolling resistance (the horizontal yellow line) occurs at pressures that are roughly inverse to the tire widths.


* For hysteresis losses in the tire. Rolling losses due to vibration (sometimes also known as suspension losses), follows different relationships, and is usually lower for wider tires.

you are right, and i was being glib, but just b/c the tire has relatively low CRR does not make it a fast tire. There's a tradeoff btwn aerodynamics and CRR, and a 35 mm tire will not do well on the former.

Why would you use a 35mm tire if you needed aero-ness?
On crap roads the 35mm Compass is faster than a 25mm Conti, which is the entire point of the Compass fat tires.
If Conti made a 35mm GP4000sii it will likely still be slower than the Compass because of design and construction difference.

you don't know that. Crr is not a stand in for how fast a tire is. It's only one of the factors.

[palincss]

No way I'd ride a 35mm tire at 87psi.

Unless you really weighed a lot -- or, like a friend of mine recently did, you misread the BQ tire pressure chart and don't realize you were supposed to divide the total weight over both wheels. Small wonder she found the tires "bouncy," running enough pressure for a 300 pound rider...

[dustyrider]

Yeah, but which one felt faster? :)

[sales guy]

100psi for a 25mm Conti 4000s II on the Mean Streets of LA would be barbaric. 70 to 80 is more civilized.

They're fat tires!
https://farm4.staticflickr.com/3669/33725493025_3d6d7b724c_b.jpg

The Vittoria sure isn't a 23! It measures out to almost 26mm.

[beeatnik]

The Vittoria sure isn't a 23! It measures out to almost 26mm.

Vittorias measure true to size for me. A 25mm on that rim actually measures 24.5. Will post a flicka later.

[ultraman6970]

A detail nobody mentions... the wider the tire the tall it is, that means the diameter of the wheel including the tire is bigger, wheel is bigger/larger/taller (word choice problem here for me ok? so just adjust to whatever you think is correct). The larger the wheel the more distance per turn it will cover, that's the reason (to me) why wider wheels are faster.

Making up numbers here ok? just for the anals that need the exact numbers, im not a lab ok? :P Imagine the 21mm tire in a 700c wheel covers 2 meters per turn, and the same wheel with a 30 mm tire covers 2 meters and 10 cm per turn, you have 10 cm more each turn between them. Per pedaling depending on the gear ratio the larger tire will cover a lot more distance than the thinner/lower one per pedaling, you end up going faster.

As for rolling resistance, well, IMO is not even that relevant because eventhought the rolling resistance and less presure put the tire closer to the ground, a larger wheel per pedaling will go quicker anyways because cover more distance per turn and even more per pedaling, the other detail is that wheels are pretty light lately, same with tire clinchers construction and compounds used to manufacture them making IMO all rolling resistance part just a tiny detail because their speed (wider and taller tires) is coming more from their diameter than from the rolling resistant part, not being anal here ok? :P

At the end IMO you can't compare a 23 mm clincher with a 30 mm road clincher, because the diameter of the wheel is different, and to me that's a flaw this tests have. A good test could be IMO is somebody one day come up with a 23 mm clincher that is thin and tall as a 30 mm clincher, that would put them at the same level for a comparison to me.

[soulspinner]

Vittorias measure true to size for me. A 25mm on that rim actually measures 24.5. Will post a flicka later.

Hey what is that rim?

[Mark McM]

A detail nobody mentions... the wider the tire the tall it is, that means the diameter of the wheel including the tire is bigger, wheel is bigger/larger/taller (word choice problem here for me ok? so just adjust to whatever you think is correct). The larger the wheel the more distance per turn it will cover, that's the reason (to me) why wider wheels are faster.

Making up numbers here ok? just for the anals that need the exact numbers, im not a lab ok? :P Imagine the 21mm tire in a 700c wheel covers 2 meters per turn, and the same wheel with a 30 mm tire covers 2 meters and 10 cm per turn, you have 10 cm more each turn between them. Per pedaling depending on the gear ratio the larger tire will cover a lot more distance than the thinner/lower one per pedaling, you end up going faster.

This explanation doesn't really work. Rolling resistance is not measured by how far the wheel turns per revolution, it is measured by power to maintain a given speed. And specifically for drum testing, speed is measured by drum speed not be wheel speed, so wheel diameter is not part of the measurement.

As for rolling resistance, well, IMO is not even that relevant because eventhought the rolling resistance and less presure put the tire closer to the ground, a larger wheel per pedaling will go quicker anyways because cover more distance per turn and even more per pedaling, the other detail is that wheels are pretty light lately, same with tire clinchers construction and compounds used to manufacture them making IMO all rolling resistance part just a tiny detail because their speed (wider and taller tires) is coming more from their diameter than from the rolling resistant part, not being anal here ok? :P

I'm not sure I understand this argument. Rolling resistance is about 15% or total resistance (on flat roads), so it is very relevant. And while it is true that a larger wheel rolls further for each revolution, for the same rotational speed, it also creates a larger effective gear ratio (i.e. it is harder to pedal for a given wheel rotational speed). There is no free lunch - larger wheels do not generate higher speeds without additional power be applied.

[tuscanyswe]

wait, so their 35mm tire is faster than the 32 or 28? really?

hmmm:bike:

Im rolling the 38s and you dont even have to pedal, they are that fast!! :banana:

I really really like these tires tho i must say.

[beeatnik]

Hey what is that rim?

Boyd 44mm clincher. They're 27mm wide (19 internally) so perfect for the Contis in terms of tire shape.