Don’t want to throw anybody under the bus, but an ostensibly reliable source from a major vendor told me that the 28 mm tire was the fastest on their wheels. I’ve never seen a tire that big rank near the top of aerodynamics or rolling resistance. I train on some 28’s and love them, But is there anyway that he could be correct?
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Re: 28mm tire Fastest?? [DBF]
[ In reply to ]
Aerodynamics is a tougher sell, but saying that 28's aren't near the top of RR is provably wrong. Of course everything is very conditions dependent, and you could read a bunch more on this thread for instance, which links to this article on Bicycle Rolling Resistance, but depending on the wheels 28's might not be awful, and they'll be comfortable. This will certainly be only 'maybe' true on the very newest generations of wheels of course.
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Re: 28mm tire Fastest?? [DBF]
[ In reply to ]
ENVE? Previously they've said 25mm were the best, but the 4000s II in 25 measure quite similar to the new 5000 28, so I could see the 5000 28 being the fastest version of that particular tire. But I don't know exactly what 25mm tire they tested fastest with.
Re: 28mm tire Fastest?? [DBF]
[ In reply to ]
He posted it for their wheel. You should be able to question the data without “throwing anyone under the bus”. I was very surprised as well and would like to see more info regarding this.
Re: 28mm tire Fastest?? [Sbernardi]
[ In reply to ]
If i remember right, what he said was the tire was tested with a 28mm version of a bontrager tire. I don't think he actually said they tested best with that tire though. Key distinction there
Re: 28mm tire Fastest?? [DBF]
[ In reply to ]
In terms of Crr the 28s will only be faster when comparing equivalent tire pressures. Using the BRR testing on the GP 5000 you can see that a 23mm at 100psi has less rolling resistance than a 28mm at 80psi. For the 28 to be faster it needs to be at 100psi. I think people often overlook this and just assume they can run the wider tire at a lower pressure for more comfortable and still be faster. This just isnt true.
The aerodynamics are a much tougher sell. Its all in context of the wheel its mounted on. A wheel optimized for 23 or 25mm tires will likely suffer with a 28 because the tire will be wider than the widest part of the rim.
The aerodynamics are a much tougher sell. Its all in context of the wheel its mounted on. A wheel optimized for 23 or 25mm tires will likely suffer with a 28 because the tire will be wider than the widest part of the rim.
Re: 28mm tire Fastest?? [TPerkin2000]
[ In reply to ]
TPerkin2000 wrote:
In terms of Crr the 28s will only be faster when comparing equivalent tire pressures. Using the BRR testing on the GP 5000 you can see that a 23mm at 100psi has less rolling resistance than a 28mm at 80psi. For the 28 to be faster it needs to be at 100psi. I think people often overlook this and just assume they can run the wider tire at a lower pressure for more comfortable and still be faster. This just isnt true. The aerodynamics are a much tougher sell. Its all in context of the wheel its mounted on. A wheel optimized for 23 or 25mm tires will likely suffer with a 28 because the tire will be wider than the widest part of the rim.
Exactly. Same tire construction and same pressures are the two assumptions behind every "wider rolls faster" claim. (Keep in mind that the same brand/model tire CAN have different constructions for different sizes.) And that doesn't take into account aerodynamics or road surface characteristics. So . . . it depends. And generally speaking, the inflation pressure range for wider tires will have a lower limit than the equivalent narrow tire -- especially relevant for smooth roads.
I suspect most people using wider tires do not pump them up to the same pressure they would use with a narrower tire. That being the case, in the real world, a wider tire is not faster most days.
Last edited by:
FlashBazbo: Feb 28, 19 8:34
Re: 28mm tire Fastest?? [DBF]
[ In reply to ]
DBF wrote:
Don’t want to throw anybody under the bus, but an ostensibly reliable source from a major vendor told me that the 28 mm tire was the fastest on their wheels. I’ve never seen a tire that big rank near the top of aerodynamics or rolling resistance. I train on some 28’s and love them, But is there anyway that he could be correct?Sure, this could possibly be true, especially if their particular wheels have quite wide rims.
But there is no way that a 28mm tire would be fastest overall (on a different, narrower, wheel) due to aero and rolling resistance factors.
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Re: 28mm tire Fastest?? [DarkSpeedWorks]
[ In reply to ]
White paper stated tests with R4 25mm tire, with a rim width (outer) of 28mm
“One key step for CFD is creating a tire model that correctly mimics an inflated tire and that changes shape like a real tire as the inner rim changes width. This allowed us to look for the ideal inner and outer rim width to use for aerodynamics with a 25c tire.”
“One key step for CFD is creating a tire model that correctly mimics an inflated tire and that changes shape like a real tire as the inner rim changes width. This allowed us to look for the ideal inner and outer rim width to use for aerodynamics with a 25c tire.”
Don't know don't care. They are probably the nicest ride at 90lbs psi unless it is a 32mm.