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From: Roger Merriman <roger@sarlet.com>
Newsgroups: rec.bicycles.tech
Subject: Re: Tire pressure
Date: 10 Apr 2025 09:22:14 GMT
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Mark J cleary <mcleary08@comcast.net> wrote:
> On 4/7/2025 5:20 PM, Roger Merriman wrote:
>> Mark J cleary <mcleary08@comcast.net> wrote:
>>> I am going to Conti GP 5000 32mm clincher tires. I weight 170 pounds and
>>> the bike and the stuff lets just say 25  pounds. Standard Shimano disk
>>> rims  RS171 is the wheels. According to the various on line calculators
>>> they suggest I use a tire pressure of 62 rear and 60 front. A few put
>>> them up to 68psi in the rear.
>>> 
>>> To me this is drastically lower than what I am using on the 28's. I
>>> might have the 28's drop to around 75 front and 80 rear before I
>>> reinflate but I am surprised. Maybe I am just way off the mark and
>>> putting in to high psi. What would you experts say. Naturally the 32's
>>> are going to be less but maybe now even on the 28's I am running to
>>> much. I usually get the rear up to around 90 and front 80 and then let
>>> them ride lower for maybe a week or so depends. But 62 is way down the
>>> line.
>> 
>> My “old school roadie” that I use for the commute, I run with a bit of
>> extra air in them, at 80psi with the 32mm tyres, I’m 200+ lb let alone bike
>> and pannier and kit!
>> 
>> 60ish sounds about right really, thought these things are guides.
>> 
>> Note that brains aren’t very good at speed, squishy = slow and hard = fast
>> to the monkey brain! I’ve had to retrain the monkey over time, as I
>> certainly used to be 120ish
>> 
>> Roger Merriman
> I put the new Conti's on today and they measure out a 31mm I am 
> surprised maybe the will change as I ride them. Hopefully can ride 
> tomorrow.
> 
What’s your wheels internal rim width that will have an effect, my MTB new
wheelset is purposely on the narrow side for modern wheels as otherwise it
would cause clearance issues for the MTB, with 30mm internal rim vs 25mm

22/23mm for road bikes seems to be about normal nowadays.

Roger Merriman