[haswell]

The Diverge was on my shortlist when I got the Topstone. At the time (2019), I think the Diverge defaulted to skinnier smoother tires. Can’t remember which tires specifically.

The Topstone shipped with some pretty knobby WTBs that definitely had an impact on rolling resistance. If your tires are knobby/optimized for off-road, putting a slicker tire (the GK slicks are quite popular for good reason), I suspect you’ll notice quite a difference, but I’d look more at the knobbiness than the fatness if you’re considering a change.

Also worth noting that some knobby tires have a hard line down the middle that keeps resistance minimal until you start to turn, at which point you hit the high traction portion of the tire. Takeaway: even if it looks knobby, it might not be as slow as it looks.

32mm+ is already getting into “fat” territory for a road bike, and for me personally, 38mm seems to be my sweet spot.

[jaypeg25]

They came with 35mm "roadsport flak jacket" https://www.specialized.com/us/en/roadsport/p/155765?color=2....

They're pretty smooth overall, perhaps why I never really had an issue commuting with them, but I'm always looking to go faster!

[haswell]

Found the details - I went from 40mm WTB Nanos [0] to these 38mm GravelKing Slicks [1]. If you look at the product pages, the difference is pretty striking. I don't know much about the RoadSports, but at least when it comes to "slick-ness", it looks like you're already starting from a slicker baseline than I was.

- [0] https://www.wtb.com/products/nano-40c

- [1] https://www.panaracerusa.com/products/gravelking-slick-foldi...

[petre]

You could try Gravelking slicks which are fast and still grippy or Conti GP5000s which are very fast.

[ehnto]

I have enjoyed the WTB Trailblazers as they are knobby enough to run singletrack but have a solid centerline for touring longevity and better rolling resistance. You just have to adjust the tire pressure according to what you're predominantly doing that day. Commutting I run them at 35-45psi and on the trail I run them at 18-22psi no worries.