On 7/21/2020 1:52 PM, wrote:
On Monday, July 20, 2020 at 5:10:44 PM UTC-7, AMuzi wrote:
On 7/20/2020 6:34 PM, wrote:
I think we had this discussion before but it is time to revisit it. I have been riding Vittoria Corse G+ 25 mm tires. Somehow I had gotten the idea that these were faster than the 28 mm tires I had been using 5 or so years ago. Well, Since I have been switching over to clinchers again I got a set of Michelin Power 28 mm clinchers.

There is a sharp descent and a long slightly downhill section I travel on regularly. There is a radar speed limit sign on this route so that I can double check my speedo. My speed through this rough area is normally 24 mph on the sign and about that on my speedo. I just changed over to the 28 mm tires and did that section and the radar reported 26 mph through this section. And the fatter tires at a 10 psi less inflation pressure rode so much smoother that I cannot for the life of me remember why I changed to the 25's.

Before I had 23's on my Time and you simply could not ride that Time with 23's on it unless you had a butt of cast iron. When I changed to the 28's on the Time it was and entirely different bike.

As you probably know, I am 6'4" and 190 lbs so I'm sure there is some dividing point though I don't know where that might be since the Tour riders are using 26 mm sew-up tires on their bikes. But I can tell you I won't make that mistake again and I will be riding 28's from now on.



I don't know but there are more factors such as ambient air
pressure and humidity, wind etc. Also new tires are
definitely faster than worn (flat center) tires.

The Vittoria tires show no flat spots and are reportedly the tires with the lowest rolling resistance.

If that's rolling resistance as measured by a smooth drum test, I don't
think it's worth much.


--
- Frank Krygowski