Tyre pressure road bike

[Weber]

Hello there,

I always used 100 psi on my wheels, when I used 23mm and 25mm as wel.

But I read on the internet that when using 25mm tires one should lower it and even when the rim is wider like 21mm inner I could lower it even more being someone like me weighing 72 kilos it could reach use 70psi.

Do you guys ride lowering the PSIs on your road bikes that much?

Is there any note of how much they use for example the worldtour?

For example this is the psi chart from LB https://www.lightbicycle.com/support/us ... &content=4

its insane 75psi.

Could you share your experience with me?

[DaveS]

Use the pressure calculator at zipp.com. Works for me.

[Hexsense]

My data point: 64kg rider using
25c tire on 23mm internal width rim on the front,
28c tire on 25mm internal width rim on the rear,
I use 58psi on both wheels. Yes, 25c tire using 58psi. That's not a mistake. It's not really squishy either, wide rim really works.

[Weber]

Use the pressure calculator at zipp.com. Works for me.

Thanks Daves. I tried it and it gave me this result

[Hexsense]

Change surface to wet in the calculator.
Wet pressure works in dry, but dry pressure compromise grip a bit in wet.

[bobones]

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[justRideIt]

My data point: 64kg rider using
25c tire on 23mm internal width rim on the front,
28c tire on 25mm internal width rim on the rear,
I use 58psi on both wheels. Yes, 25c tire using 58psi. That's not a mistake. It's not really squishy either, wide rim really works.

My setup:

Wheelset: Roval CLX 50 (21mm internal width)
Tires: Continental GP 5000 tube-type, 28mm (measures 29.8mm on above rims), front & rear.
Tube: Vittoria Latex
Frame: Tarmac SL6

At 65 kg, I run 48 PSI front and rear.
Road conditions far from pristine.

No flats, no tires coming off, hassle-free all around and most importantly: very fast & comfortable.

With 100 PSI on 23mm tire, I would never ride the bike. I would hate how the ride beats me up.

[ghostinthemachine]

Note it uses measured tire width, not sidewall label.

an important point. My largest road tires are 4 mm wider than the label when fitted, which makes about 1 bar difference in recommended pressures.

[Weber]

Silca Pro Pressure Calculator is a good one. Note it uses measured tire width, not sidewall label.
https://silca.cc/pages/sppc-form

Note it uses measured tire width, not sidewall label.

an important point. My largest road tires are 4 mm wider than the label when fitted, which makes about 1 bar difference in recommended pressures.

This real tire width apply on Zipp calculator too?

[bobones]

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[ryanw]

The SRAM / ZIPP calculator is much better than the Silca one. Takes rim ID into account which has a huge part to play in tyre pressures.

[bobones]

...

[Weber]

The new standard on road bike if it were possible to specify it, are the rims of 21mm inner width?

I saw that roval makes them at least 21mm

[ryanw]

The SRAM / ZIPP calculator is much better than the Silca one. Takes rim ID into account which has a huge part to play in tyre pressures.

The Silca one uses the measured tyre width so the internal rim diameter is accounted for.

No it doesn't. Lets not get cofused with pressure and volume here.

A narrow rim with wide tyre and a wide rim with the same width tyre can have an almost identical tyre width, but the tyre profile is very different (lightbulb vs flat sidewalls).

The volume of the tyre shall always be identical since it is a 2D object, but the rim volume is much smaller on a narrow wheel, so the total system volume shall differ.

Greater volume = lower pressure, Boyle's Law and all that.

[Lewn777]

I've been told that some people can tell the difference between thinner and thicker butyl tubes or latex and rims that are 2mm wider. Supposedly the reason I can't tell the difference is that I run too high pressures or crap tires or something. Honestly I can only just tell the difference between tubeless and tubed road tires, therefore those people have over-active imaginations IMO.

There is no prefect psi for your weight it depends on road surface. Same rider tires and wheels you'd match the pressure to the road - super smooth bitumen roads, run high pressures like 100psi. Rough roads like Paris-Roubaix much lower maybe 50-60psi, DH MTB 20-30psi. These calculators seem like nonsense to me unless you are simply running them on a 'super-smooth bitumen at all times' algorithm.

Of course rider weight does come into the equation, but it's a percentage less for lighter riders plus bike after accounting for road surface.