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garciawork

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Reply with quote  #1 
I am sure this has been covered, so apologies. But what pressure would any of y'all in the know recommend for for a set of 35c Schwalbe G one's, mostly on pavement? When I am back in shape, gravel/dirt will be a factor, I am just now getting to some base miles, and don't plan to swap tires. I know my MTB and road pressures quite well, but man I have no idea what to do here, and would rather get a good baseline and experiment from there. Thanks! 
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Volsung

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Reply with quote  #2 
How much do you and your bike weigh and what's the weight distribution like on your bike?

My bike is set up fairly upright so I've been like 10 or more PSI lower up front.
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chas

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Reply with quote  #3 
I am 175lbs  and for 40mm I use
Gravel:  35F 40R
Road:    45F 55R

I might bump that up 5psi for 35mm tires.  and go up or down depending on the road surface and my mood for the day.

The Original chart that changed everything is here:
https://janheine.wordpress.com/2016/03/09/tire-pressure-take-home/

Then again, there is the tried and true Cyclocross method:  go down in pressure until you start bottoming out, then add some back in.  ;-)

All the above works best tubless.

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garciawork

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Reply with quote  #4 
Quote:
Originally Posted by Volsung
How much do you and your bike weigh and what's the weight distribution like on your bike?

My bike is set up fairly upright so I've been like 10 or more PSI lower up front.


Wow... I completely meant to post weight. I am about 157, bike is 23.5, and a little on the racy side? I have some saddle to bar drop, but nothing crazy. 
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garciawork

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Reply with quote  #5 
Quote:
Originally Posted by chas
I am 175lbs  and for 40mm I use
Gravel:  35F 40R
Road:    45F 55R

I might bump that up 5psi for 35mm tires.  and go up or down depending on the road surface and my mood for the day.

The Original chart that changed everything is here:
https://janheine.wordpress.com/2016/03/09/tire-pressure-take-home/

Then again, there is the tried and true Cyclocross method:  go down in pressure until you start bottoming out, then add some back in.  ;-)

All the above works best tubless.



Thanks for the link! And my tires are most certainly tubeless. Haven't used a tube since 2009 if memory serves! 
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bobknh

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Reply with quote  #6 
Quote:
Originally Posted by chas
I am 175lbs  and for 40mm I use
Gravel:  35F 40R
Road:    45F 55R

I might bump that up 5psi for 35mm tires.  and go up or down depending on the road surface and my mood for the day.

The Original chart that changed everything is here:
https://janheine.wordpress.com/2016/03/09/tire-pressure-take-home/

Then again, there is the tried and true Cyclocross method:  go down in pressure until you start bottoming out, then add some back in.  ;-)

All the above works best tubless.


The Berto chart is far from scientific. It assumes that a certain tire deflection is optimal. But that is only a guess; and is based on tubular (sew-up) tires. None the less, I've been using it as a good starting point with my own set-ups assuming that the rear tire is bearing 60% of the total weight of bike and rider. Depending on the tire I'm using, I find that I can easily go somewhat lower than the Berto charts would predict - especially for the front. And, tubeless changes things a bit since there is less risk of pinch flats. My method - actually recommended by the boys at GCN- is to start with either the Berto ideal pressure or the manufacturer recommended minimum pressure; and keep lowering the pressure until I find the lowest that doesn't seem to have excessive tire squirm. I only weigh 147 pounds and my gravel bikes around 20. I've found that on most 35-40mm tubless tires I ride, that 35/30 rear/front works pretty well. That goes for Compass Bon Jon's, Gravel Kings, Ramblers, and Schwalbe G-ones. Another factor to consider is hoop pressure on the rim, which is proportional to the tire diameter. A 45 mm tire exerts almost twice the inward pressure on your rim as does a 23 mm tire at the same inflation. For example, if the max inflation for a 23 mm tire on your wheel is 120 PSI, then the max inflation for a 45 mm tire is only 60 PSI. I believe that too much hoop pressure on the rim can possibly lead to loosening spoke nipples and spoke failure. 
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