I prepped the 5200 for duty last evening. It was going to be a slow night and it needed some time in the sun after the Venge took all of the big weekend miles.
After watching that exceptionally geeky video I wrote about the other day that broke tire pressure down into a fairly* easily understandable science, I decided to lower my pressure in both road bikes. Not by much, mind you, I went from 95 pounds down to 90.
On the Trek, left, I’m currently running Ican 23-mm wide x 38-mm deep wheels shod with Michelin Pro 4 Service Course 700C x 25-mm tires. I’m running 175-ish pounds. So, 90 pounds and I ran with it.
The road we live on is fairly smooth with a few wear cracks here and there at the edges, but the road I turn on to get to Chuck’s is gnarly in places and the bike was much more enjoyable over the chatter – in fact, I ran over some of the nastier edges of the road I normally avoid, just to see the difference… it was impressive – vastly smoother. On chip-seal surfaces, cracks, anything I would throw at it over the course of the 28-mile ride, the bike was much more enjoyable… and I didn’t bounce when out of the saddle to climb or sprint (what little climbing there is on that route – not much).
So, the real question is, “was it faster“?
Well, if you get far enough into the video, the science geek guy refers to road noise as a loss of efficiency – and road noise from the tire definitely increased, noticeably. On the other hand, there’s no question the ride, being smoother, was less taxing and slightly less work. That’s really the balance we’re looking for. Smooth, but not so smooth it’s squishy. I think I should go another five pounds, though, just for $#!+$ and giggles, to see if I go squishy or keep 85 psi… There’s no question, even at 90 there will be more smiles per mile.
*”Fairly” should probably be barely.
Then I’ll have to dial in the Venge using the same process – though I’ll absolutely be going with 90 psi for tonight’s Tuesday Night in Lennon… I’m running 26-mm Specialized Turbo Pro tires on a 25-mm wide rim – shouldn’t be any question 90 will be better than 95.
Fit Recovery 
Back in the drag racing days, we used to run higher pressure in the front tires.
This would cause the outer portions of the tread, to not make contact with the road. It was supposedly worth 100th or 2 of a second, in total elapsed time.
Less contact patch on the front, as opposed to the rear, where we would let air out of the tires to make sure all of the tread available was on the road.
I guess it’s all about that fine balance between speed and comfort. For a “recreational” road cyclist going lower might be be more beneficial than for more “serious” folk? It’d be vastly more comfortable and the speed loss would be negligible for them. Keep up the great testing!
Absolutely!
It does make a difference