It’d be wrong to say that the 26c will be faster in all conditions vs. the 28c, or vice versa. But overall, I can say that typically the 28c will be faster rolling wise, especially at lower pressures and/or wider rims. Our recommendations in terms of pressure (check our website) is probably lower than what most calculators would suggest. When you add the additional comfort and grip advantage, this is why I run 28c both front and back - having anything smaller than 28c at the rear makes little sense.
Now, as always, the aerodynamics will substantially vary depending on the whole system (bike/fork/wheel…). If you see a pro team running 26c rather than 28c, you can assume that this was tested on the final bike set-up and on the actual course they’ll be riding.
We’ll look as to what we can publish in terms of actual (testing) data but I can confidently say that we have tested and worked with multiple partners on this last iteration. I’ve personally been very excited to see it get released!
If it’d be of interest and if we can pull together some specific topics, I’d be happy to do a bit of a Q&A.
What size internal rim please?
I have a rim with 21 internal do you think the 28 is still fastest?
Glad you asked, I am also wondering about running a 28 conti 5000 or S TR version for a Hed Jet+ rim. I wonder if it is too big a tire or not. I also have the newer Pirelli P Zero Race tire that is tubeless in a 26.
So, tire gurus…What do you say, 25 GP5k, 28 GP5k or 26 Pirelli P Zero Race (new one) for a HED Jet+ front wheel?