On Thu, 27 Feb 2020 15:45:33 -0800 (PST), Mark Cleary
wrote:

On Thursday, February 27, 2020 at 1:15:06 PM UTC-6, Mark Cleary wrote:
I have a set of wheels with these rims and utlegra hubs 32 hole. I like the rims 23 25 mm profile. As usual when I got them I did do a quick go around to make sure spoke tension ok. So after maybe 2300 miles they are doing great. My question is maybe I can ride at lower PSI and I don't give it a chance.

I run these at about 100 psi on the rear and maybe 93 ish on the front. No pinch flats I am 6'1 and about 170 pounds. What PSI would you ride these at? Sure I could just keep dropping the psi in till I go overboard but now another question.

I run Conti PR 4000 II 23mm presently. I am an old school mind and the 25 just don't want to stick in my brain. Since I am due for a new set of tires should I go 25 they seem to inflate pretty close to the stated width. Then could I get even lower PSI and. be better of than the 23's. I am I trying to split hairs and it does not matter. I do like a smooth ride but of course speed always in the back of my mind hate to ride slow if I can go faster.

Deacon Mark Cleary

Yes I have the Archtype rim. Wow going to a 25 and they low of pressure will be quite a change can I absorb it all a once?

Deacon Mark

Bicycle Quarterly (Jan Heine) published an article some time ago where
he stated that tire testing had shown that a "tire drop", i.e., the
tire being compressed against the ground, of 15% resulted in the most
efficient tire pressure. He also discusses, in little detail, that the
tire load may vary from front to back. A Randonneur bike, he reckons,
has a front and rear tire load of 45%/55%, a racing bike, 40%/60%, for
example.

He tested various gross weights and published a gross weight versus
ideal tire pressure chart for common tire sizes. Example: a 170 lb
individual on a 15 lb. bicycle has a gross weight of 185 lbs.
Assuming, as an example, a 50%/50% front to rear wheel loading each
wheel will support 92.5 lb. Looking at B.Q.'s chart a 23mm tire will
require ~100 psi, A 25mm tire ~90 psi and a 28mm tire ~70 psi.
see
https://www.biketinker.com/2010/bike...-for-bicycles/
for reference.

As an aside, I did weigh my bike and rider for front and rear tire
loads and for a steel frame, classic type, bike with rider in the
normal road bike position (hands on the brake levers) I found a
50%/50% weight distribution.

--
cheers,

John B.