Pressure and p******* proofing

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gbs

Guru
Location
Fulham
I normally run at the high end of tyre manufcturers' recommended pressures, typically 7-9 bar. If I reduce to the lower end of that range I will expect some gain in comfort and grip and some increase in rolling resistance. Will there be any change in the p******* resistance?
 
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Will Spin

Über Member
Theoretically yes, as the surface area of the tyre that's in contact with the road and which is therefore likely to encounter potential puncture causing matter will increase.
 

Thorn Sherpa

Über Member
Location
Doncaster
I run my Marathon+ quite hard normally 55psi (26x2") running them with lower psi in my mind your gonna risk pinch flats and the rolling resistance. I use mine for the commute and leisure rides so I'd rather have a slightly harsher ride than risk a puncture imo
 

Slick

Guru
I run my Marathon+ quite hard normally 55psi (26x2") running them with lower psi in my mind your gonna risk pinch flats and the rolling resistance. I use mine for the commute and leisure rides so I'd rather have a slightly harsher ride than risk a puncture imo
Is 55 psi quite hard? I normally run quite a bit higher than that, but I suppose I'm no Chris Froome.
 

mjr

Comfy armchair to one person & a plank to the next
Theoretically yes, as the surface area of the tyre that's in contact with the road and which is therefore likely to encounter potential puncture causing matter will increase.
But it'll encounter them while exerting less force onto the sharp object, thereby reducing the ease it pushes through the protection. I suspect it pretty much cancels out the increased risk of a larger contact patch, so I tend to favour comfort as long as my maximum load doesn't risk pinch flats. Our roads are rough so what I lose in rolling resistance is more than gained back in reduced suspension losses.
 

Ajax Bay

Guru
Location
East Devon
If I reduce to the lower end of that range [7-9 bar/100-125psi] . . . will there be any change in the p******* resistance?
I don't think it'll make any difference.
The additional surface area in contact is about 30% more but perhaps that extra area is subject to 'less threat' as @mjr has suggested.
The OP doesn't say what width their tyres are or how heavy the rider plus bike is, but see the attachment for a tyre pressure readout.
I run my Marathon+ quite hard normally 55psi (26x2")
55psi seems extremely high for 26" 2" wide tyres: way above any risk of pinch flats and sacrificing some comfort. On the other hand, 55psi is likely to be far too low for a 28mm wide front tyre unless a very light (<55kg) lady is on board.
 

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Slick

Guru
The tires feel quite hard I think 55psi is enough for 26 inch tires but probably not hard enough for road bikes?
Ahh, talk about assumptions. Your right, I was talking about a road bike.
 

si_c

Guru
Location
Wirral
I think that if you have a half decent tyre, and maintain the pressure at a level sufficient to avoid pinch flats, you pretty much have nothing to worry about.
 

Thorn Sherpa

Über Member
Location
Doncaster
I don't think it'll make any difference.
The additional surface area in contact is about 30% more but perhaps that extra area is subject to 'less threat' as @mjr has suggested.
The OP doesn't say what width their tyres are or how heavy the rider plus bike is, but see the attachment for a tyre pressure readout.

55psi seems extremely high for 26" 2" wide tyres: way above any risk of pinch flats and sacrificing some comfort. On the other hand, 55psi is likely to be far too low for a 28mm wide front tyre unless a very light (<55kg) lady is on board.

Just had a look on the chart and it sounds about right I stay around the 66-68kg mark so with the 2" wide tyres 55psi seems alright? I'm definitely no expert on tyre pressure like others say I pump them up till they feel hard enough which is around 55 psi!
 

Banjo

Fuelled with Jelly Babies
Location
South Wales
I think tyre selection is more important than exact pressure.

After some incredibly bad experiences with various other tyres I am finding my durano plus very durable and puncture proof.
 
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