45 vs 40 tires, is wider more grip but slower?

[toronto-rider]

THinking of getting the Schwalbe G-One RS to run as my tire for next year.
Most of my gravel rides, involve a fair amount of road and the gravel is not super technical.
I also do a fairy amount of gravel races. I know you cant get the ideal gravel tire that meets all of your needs all the time, either you sacrifice speed for grip.

If I go with the 45, I will be able to run lower pressure and hence will be in better shape when the grip and gravel require something with more tread. However, will the 45 be much slower than the 40 overall due to the better rolling resistance on the road?

Thoughts?

[Singular]

Nopes - rolling resistance is more or less equal across widths if construction/material is identical. What you will experience is higher weight (which can be a negative AND a positive) and a, to a degree depending on a few factors, higher aerodynamic drag with the wider tire.

[stoney]

You will just face an aero drag and weight penalty with the 45.

[blaugrana]

It's a bit hard to compare, because when you go to a wider tyre the pressure must be reduced, but what reduction should be accounted to make the tests "fair"? Generally the point of wide tyres on gravel is to be able to run much lower pressures without bottoming out the the rim (you can run a softer tyre because there is more "travel" available, if you look at it like a suspension).

If the gravel is not technical I would go for the 40s, especially considering that you are going to ride on the road as well. I am never quite as comfortable in these very wide gravel tyres run at soft pressures when riding on the road, as when riding out of the saddle and sprinting, bouncing up and down is quite inevitable. And if you don't run them at such a low pressure, you don't really gain much on gravel and you are basically carrying extra weight and aero drag for nothing.

[yinzerniner]

THinking of getting the Schwalbe G-One RS to run as my tire for next year.
Most of my gravel rides, involve a fair amount of road and the gravel is not super technical.
I also do a fairy amount of gravel races. I know you cant get the ideal gravel tire that meets all of your needs all the time, either you sacrifice speed for grip.

If I go with the 45, I will be able to run lower pressure and hence will be in better shape when the grip and gravel require something with more tread. However, will the 45 be much slower than the 40 overall due to the better rolling resistance on the road?

Thoughts?

If you normalize for casing tension and/or tire drop then you'll have higher pressure on the 40s and lower pressure on the 45s, but the rolling resistance will be about the same. The 40s will obviously be faster due to aero drag, while the 45s will have better grip due to the tread width.

The lower pressure of the 45's is a bit of a red herring - the casing tension of the 45s are higher at the same PSI/BAR vs tge 40's, but the grip on off-road conditions will probably be worse on 45's at the samre pressure as 40s since the tire wont' be able to deform as much.

As long as your surfact conditions are OK for 40mm tires you're better off using them on the road and carrying a small pump to change the pressure depending on surface.

[Nohands83]

Some data on the aero penalty of 40 vs 45mm tyres below. Spoiler - it's not very much, particularly at the speeds at which most people ride gravel.
https://www.swissside.com/blogs/news/gr ... ?locale=en

[txg]

I would vote for the 45mm, based on the following experience:

I do run 35mm Conti Terra Speed, 40mm Schwalbe G-One Bite and 44mm Tufo Thundero in my Gravelbike.

The Terra Speed are very fast but have rather bad grip especially in wet conditions but also on dry forest paths.

The G-One Bite have an insane amount of grip (even on snow) but are extremely slow on tarmac. There is a big difference to the two other tires that can be felt immediately.

The 44mm wide Tufo Thundero on the other hand do not feel slower than the Terra Speed (though they probably are a very small bit slower) and are the most comfortable on rough paths. They have enough grip for me but probably not as much as the G-One Bite (haven't tested the Thundero in Snow so far). I like them the most and use them at about 1.8 bars (65kg rider). Yes, there is a bit of bouncing when riding on roads but to me it is not that annoying.

If you want to optimize aerodynamics, have a look at your position and the kit you are wearing. There are MUCH bigger gains to be made than with aero optimized tires.

[MikeD]

The rolling resistance makes more difference than the width when wide tires are concerned. Check bicyclerollongresistance.com.

That said, my gravel bike is 1 mph average slower than my road bike, and I attribute most of that difference to the width of the tires. There's no comparison in rolling resistance between a high quality 25mm tire vs a 40mm one. Gravel tires are going to have stiffer sidewalls/casings which cause higher rolling resistance. An exception may be Rene Herse tires that seem to be built like fast road bike tires.

[warthog101]

Nopes - rolling resistance is more or less equal across widths if construction/material is identical. What you will experience is higher weight (which can be a negative AND a positive) and a, to a degree depending on a few factors, higher aerodynamic drag with the wider tire.

You will just face an aero drag and weight penalty with the 45.

My thoughts also.
I run 40s.
At the couple of gravel races I've done there was nothing wider.

[toronto-rider]

Thanks for all the replies. I plan to run the 40's.