unbelievably

How low can I run 32's?
I'm 85kg.

lunacycle

I've run 32mm cyclocross tires (clinchers) as low as 55psi for racing, and I weigh about 80kg. However, I usually keep them up around 75-80 psi on the road.

alanbikehouston

Kg? Don't know. As a rule of thumb, the weight of the rider should cause 15% deflection of the sidewall when he gets on the bike. That 15% of "sag" is just enough that a person behind the bike sees the rim move very slightly toward the pavement.

If the sidewalls have "zero" flex when you get on the bike, the tires are not going to absorb road shock. If the rims sag almost down to the pavement, you get pinchflats. So, there is some trial and error involved.

I suspect a CAREFUL 160 pound rider who doesn't plow into rocks and curbs could do well at about 50 PSI front and 60 PSI rear. The guys who weigh 260 pounds have a different problem: even if they use the maximum PSI stamped on the tire (say...90 PSI), they may be getting too much sidewall sag.

unbelievably

I'm in the process of trying to skip these steps by asking. Thanks...

Psimet2001 

I have posted formulas that give great guidelines for normal inflation, but that doesn't answer the question you posed "how low" you can go.

I have personally witnessed many CX racers ride in the mid to low 40s in "dewy" conditions. These guys were in the 150-170 lb range.

Exchange I overheard went something like this:

"I was all over the place."
"What are you running?"
"48 rear"
"DUDE! No wonder, that's way too high. We all running 42-43."

Unfortunately trial and error is the only way to know for sure.

operator

Good for you. There is no such thing. There are too many combos of tubes, tires, rider weights and frames/components. Someone can give you a ballpark but nobody can tell you what exactly.

unbelievably

If there is a range that might be in the low/middle/high psi.
This kinda info is out there...I know it is!

ChunkyB

It is out there. It's on the side of your freaking tire.

How hard is trial and error with tire pressure. Ride a few miles, get off your bike, pump up tire/let air out, repeat as desired.

BTW, I wouldn't be rude if you weren't rude to the repliers, especially the one person that obviously spent some time giving you a thoughtful reply.

unbelievably

My goodness...
I swear,
if the use of these icons in my posts makes me come off as rude, well...
Then I guess I'll have to read up on internet forum etiquette.

You gotta remember,
this ain't a tea party at Buckingham Palace.

ChunkyB

You're the one that got miffed when someone suggest that there's a trial and error period.

Oh, btw, I thought this was a tea party at Buckingham Palace. The admins are going to hear about this. I want my tea.

elgalad

You get put out too easily.

I didn't read anything that suggests the poster is "miffed" about anything. He acknowledged that he could work it out by trial and error, and asked if he could make this easier by getting a ballpark figure to start from.

I don't buy the idea that anything other than weight and perhaps tyre type affect minimum inflation pressures.

ChunkyB

Terrain?