Woah that’s a high pressure.
That really depends on the all up weight of rider and bike.
Obviously. But for most people here that’s probably way too high. For a rear pressure of 80psi on 30s, that’s a 130kg rider and a 10kg bike. For me at 85kg, I’m at like 62psi.
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Yeah, that used to be me. 110kg plus bike needed 85psi on 28mm tires. Now I weigh the same, but run my 44mm Snoqualmie Pass slicks at 43psi and my speeds are as fast, or maybe faster, than they were before because the tires are really absorbing more of the bumps.
As I lose weight, I’ll probably eventually drop down to 38mm for the road. I think. Those 44mm are sooooo comfortable…
tell it to silca! 
Just trying to pick the closest BRR data point to the closest Silca pressure calculator rec.
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They are actually lower than the SRAM calculator I used. Silca says it would need over 170kg system weight to recommend 80psi. I’m not saying there are no cyclists out there that weigh that, but they’re in the minority. And that’s a 30mm measured tire. My 30s measure 31.3mm, which goes to 200kg system weight to recommend 80psi. So unless you’re 200kg, 80psi is way too high.
No it doesn’t. Hit the reload button. Or contact their customer support.
And if you want to know whether 28mm tires or 30mm tires are better…go with the 28’s. The data clearly support that choice and, as this thread demonstrates, the only argument for the 30mm tire is that you will ‘feel better’ after riding for a ‘long time’. That’s subjective, not evidence.
Good luck with the Silca widget!
Just double checked everything and here it is.
Lol, what data? Where is this data that clearly shows an advantage? Everything is pointing to wider being faster. Hence why the World Tour pros are going wider and wider. Even Dan Bingham (a guy who places a huge emphasis on aero) is going wide…on the track, which is the one place narrower could have ever argued to be faster.
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Just for fun I just checked this
Now, as I said, the closest BRR data point is 80 psi. Glad I could help! Good luck with that Silca widget.
Atta boy! Laugh it off!
As detailed earlier in this thread:
rolling resistance: no measurable difference. Maybe 150mW advantage to the 30s.
weight: 60g advantage to 28s
aerodynamics: Enve doesn’t recommend the 30’s. At higher yaw angles, 2-4 watts lost
You have a 28 tire selected. Your original post which I responded to said a 30mm tire. And it’s more funny that even a 28 doesn’t recommend 80psi.
Just for fun I checked the 30 you quoted in your first comment and it recommends 69.5psi. 
Yes, that’s correct. And when you refer to the 2nd graphic that I posted…also note there that the BRR data is for 28mm vs 32mm. So not a 1:1 comparison.
But, but, a 30mm GP 5k is only going to be closer to the 28. So at 80psi crr difference between the 28 and the 32 is 200 milliWatts…the difference will only be smaller between a 28 and a 30. So I’m being generous when I say it might be 150mW. More likely it’s less than 100mW difference. de minimis.
But the weight advantage is measureable. Not large but clear avantage to the 28’s.
And the aero disadvantage at yaw is also material. Which is a big part of the reason Enve don’t recommend tires that wide for that wheelset. But, as I said, if you know you ride a moderate distance on 28s and experience a 20W decrement in performance vs riding a moderate distrance on 30mm tires…well, I think you should consider other wheels and capture both gains. Other wheel options are available, as they say.
I’ll keep that in mind the next time I ride or race on a steel drum.
And you’ll notice I never argued about aerodynamics or weight of bigger tires (even though it’s been proven weight has a minuscule impact on speed). I was literally just saying that 80psi on 30s, like you stated, is way too high of a pressure to run for the vast majority of cyclists.
@Junk_Miles, I know you asked what data supported the notion that 28’s are the clear choice…so just to reiterate:
1.) The rolling resistance between 28’s and 30’s is going to be at best mW. No material difference.
2.) There is a clear weight advantage to the 28’s.
3.) There is a clear aerodynamic advantage to the 28’s. Especially at yaw. Which is probably why the manufacturer don’t recommend larger tires on that wheelset.
Some posters in this thread have said that if they ride a moderate distance on 28mm tires they will experience a 20W decrement in performance vs riding a moderate distance on 30mm tires. If you are in this cohort, it’s probably a good idea to go with a different wheelset that has greater aerodynamic performance at yaw with wider tires.
Silca calculator suggestions are useless, because they don’t take the rim width into account. The pressure for a tyre installed on some old 17 mm rim is totally different than for a tyre on 25 mm rim.
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A 25 mm tyre will measure just over 27 mm on the Enve foundation wheel. The 28 will be closer to 30 mm.
I use a 25 mm front and 28 mm rear as I also like to do time trials on my road bike where I’ll average 42 km/h+ so aero is important.
I’m not ready yet to buy wide wheels (mine are only a year old) and I refuse to give up aero so will be sticking to this. I don’t find it uncomfortable and it is still massively better compared to the 23 and 25 mm I used to run on rim brakes.
For you the safe choice is 28 mm front and 30 mm rear if you are worried about aero. I like the odd tyre sizes and it makes sense in my head.
It sort of does. It asks for the measured tire width. So that will take into account the rim width rather than the stated tire size.
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*Measured on a steel drum
There is a clear weight difference. There’s argument to whether there’s a clear advantage over that difference.
Again, never argued against this. Actually never even brought it into the discussion. Especially since it will vary with tire choice, rim width, and probably wheel depth. So many variables to say that 30mm tires are X watts slower than 28.
But to reiterate since you keep glossing over my point. Read my first response to you. That was literally my only point here. 80psi on 30s is too high for 99% of the people here. Simple statement. But you went way off tangent for some reason.
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I may not have adequately explained my points.
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Subjective: For many riders, the reduction in fatigue that comes from a wider tire at lower pressures will materially affect power output over long distances. I’m sure many racers and pointy-end people are much more durable than the majority of cyclists, but for MANY people this is a real consideration.
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Objective: Your argument ignores power losses on the narrower, higher-pressure tires due to suspension effects as the tire’s reduced compliance increases the bike’s “bouncing” (for lack of a better word) over road imperfections where a wider, lower-pressure tire will absorb some of that impact and allow the bike to travel in a more consistent path with less vertical displacement. Those effects are substantial and increasingly well-documented.
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Objective: There is a visible trend even in the fastest pro pelotons for wider tires and lower pressures. That is real-world DATA, even though it’s neither research-derived nor -intended. When even the 2023 Tour de France saw mostly 28’s (and 30’s for Paris-Roubaix), the rest of us are likely best served by running at least the 30mm tire.
I think your position was solidly supported by the best available data around 2015, maybe 2020. But today, I think your argument is missing key pieces that do change the answer.
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Huh, I must have missed where I said this.
I guess I’m just used to riding in the real world on real roads rather than in a testing facility . To each their own. Have a great day.
And you can argue about testing methods or repeatability and that’s all fine and good, but I still trust real world data with actual bikes and actual roads and actual people riding over a lab with a steel drum and an isolated tire. Real world is where I ride.
No I’m not ignoring it. I just know what it actually is.
