2 x 700C wheel sets: which tires? 38mm and 35mm?

You won't notice that much difference, I wouldn't do it. Waste of $ IMO. And as always, wider doesn't automatically mean slower. 

I think you should elaborate a bit more on what you mean by "Allround" and "Dry/Fast". Riding for fun vs racing? Wet vs dry? Etc. 

TonyM wrote:or other way to put the 38mm g-one on the 24mm wheelset and use the 20mm wheelset for something faster like a 32mm for dirt roads/ gravel? Or is that not enough width?

chas wrote:There is, practically speaking, no difference between your two tire/wheelsets.  

Personally, I run 32mm slicks for fast road rides, and a 40mm gravel tire like the G-One you mentioned.  

dangle wrote:

This is exactly what I do for my gravel wheels. The 38 Schwalbe measures a little big. It measured 42 mm on my Stan's (21 mm ID) rims. Then I have Specialized Roubaix 30/32 tires on another pair of those same rims. They stretched out to 33/34 mm. The Roubaixs down to <40 psi are surprisingly versatile. I may go to the Schwalbe G One Bite or the new Continental Terra series when it's time to replace the G Ones.

As others said, running a 35 and 38/40 of two identical tires doesn't make sense. You will always be reaching for the 38/40.

HollyBoni wrote:
Any reason why you think a narrower tyre will be faster for offroad riding? Seriously not trying to be a smartass, but my experience has been the exact opposite. If you look around, pretty much every offroad discipline (including gravel) has been moving to wider tyres for a while now. I have GravelKing SKs in 40mm and 32mm. With the 32s I can't run anywhere near as low pressures as I can with the 40s, which results in a much more jarring ride, and much less speed on any rough surface. 

If you don't do pavement only rides on your gravel bike, and unless you want to ride both in dry weather and in a downpour and/or big mud, i'd think about running just one wheelset with an intermediate tyre like the G-One Allrounds that you ordered. For the riding you've described so far, I don't really see the need for two wheelsets and two different tyres. Just my opinion. Playing around with tyres is certainly fun tho (but can be a bit $$$). 

clarksonxc wrote:I think something like a 45mm/35mm or maybe 38mm/32mm combination would give you more of the range to make the dual setup worthwhile.  Like the 45mm set for rougher or mostly gravel rides, and the 35mm set for smoother gravel or pavement heavy rides.  Basically just put more of a difference of width between the two wheelsets to make it worthwhile.  38mm/35mm, even if slick/knobby, isn't that much of a difference.  

TonyM wrote:

Thanks for the feedback! I am new to gravel bike (for more than 30 years mostly road bike). Being a roadie and older/ conservative/ old fashioned I suppose this is why I thought that a 32mm would be faster (but less conformable) than a 38mm on gravel

As far as I know and in my experience, when riding offroad more bump absorption and a smoother ride usually means faster too. And you also see those road bike tyre rolling resistance tests where they compare tyres from 23 to 28-32, and the biggest tyre comes up on top, but i'm not smart enough to explain that in detail. 

TonyM wrote:Thanks guys for your feedback!! 

Or it is better then to have one 700C wheelset w/ 35mm or 38mm tires and one 650B wheelset w/ 2.1" for example?

TonyM wrote:Thanks guys for your feedback!! 

What do you think about this?

- 1 x wheel set (20mm inner width) with 35mm tires for allround smooth gravel.
Here I am thinking of the Schwalbe G-one in 35mm.
- 1 x wheel set (24mm inner width) with bigger tires (42-45mm) for rougher gravel.
Here I am thinking of the WTB Riddler TCS in 45mm or the WTB Resolute in 42mm.

BUT is the difference between 35mm and 42-45mm a significant difference in terms of comfort?

Or it is better then to have one 700C wheelset w/ 35mm or 38mm tires and one 650B wheelset w/ 2.1" for example?

Slim wrote:

35 to 45 mm is a big difference. If you also use a tire with more aggressive tread, it really will make a change.but, it sounds like you own the 20mmrims, and not the 24s.

Does your bike accept 650b? How big? 

I would by a 38c G1 for the rear, at higher pressures needed in the rear squirming won’t be a big deal( I run it on a 21mm rim). Then get a 35mm G1 for the front. It will feel more similar in steering feel to the road bikes you are used to.

Then go ride for a while. Check out different events and your own exploration. What do you find? Do you need more float for soft gravel? Traction for and big volume for Singletrack? Just big volume for rocks or roots?
Then you know here you want to go with a second wheel set. Maybe it’s 650b if you want max volume and a lively feel. Maybe it’s 700x50 up front for better rollover. Maybe it’s aero rims for 35mm tires.

Those max tire sizes, are those your own, measured numbers? Front and back? Most bikes have a lot of room up front.

HollyBoni wrote:And you also see those road bike tyre rolling resistance tests where they compare tyres from 23 to 28-32, and the biggest tyre comes up on top, but i'm not smart enough to explain that in detail.