Unbelievable Pressure

[Mburton1993]

Thank you all, cycle chatters, as always, providing great info!

Think I'll be trying out a few different pressures this week, once I've put my bike back together that is.

Top tip: don't go cheap with chainring bolts, they wear and are a ball ache to remove.

 

[Ming the Merciless]

I used to run my 28s at 70/60 F/R when 80kg. Pump initially high then reduce pressure till road vibration just disappears will get you in the ballpark.

 

[Deleted member 1258]

Rubino 25's, I'm 11 stone and run 80 back and 75 front, any higher and I'm in danger of loosing my fillings.

 

[Grant Fondo]

Thank you all, cycle chatters, as always, providing great info!

That Jarno Bierman fella loves his empirical data at BRR
https://www.bicyclerollingresistance.com/specials/conti-gp4000s-ii-23-25-28
Not for the faint hearted, but has he really tested all those tires? (sic)

 

[PaulSB]

69kg.
Tubes in 28mm 100 psi
Tubeless 28mm 80psi
Tubeless 35mm 60psi

 

[rogerzilla]

Even 160psi didn't save me from a pinch puncture on a sharp-edged pothole.

The trend to 28mm tyres means that < 100psi is now more normal, but 23mm tyres often need at least 120psi to protect the tube from being pinched.

 

[Gunk]

100psi has always been my default pressure with tubed road bikes however with a 28c tyre I have dropped to 85psi which makes city riding a bit more comfortable

I’m 73 kgs

 

[Venod]

Rubino 25's, I'm 11 stone and run 80 back and 75 front,

I ran the same pressures in Rubino 25's with tubes 11.5 stone.

Now all wheels are tubeless, the narrowest I have are 30mm and I run these at 60psi

 

[Cycleops]

Top tip: don't go cheap with chainring bolts, they wear and are a ball ache to remove.

Do you mean you’re rounding off the Allen key? This can be due to dirt collecting in the bolt holes causing the key not to locate properly. Always a good idea to clean them out and and give the Allen key a good tap to make sure it’s home. Never had a problem.

 

[FishFright]

I used to run my 28s at 70/60 F/R when 80kg. Pump initially high then reduce pressure till road vibration just disappears will get you in the ballpark.

I really like that description , I will be using it myself .

 

[sleuthey]

I run my 32s at 60/65psi Fr/Rr and that includes my 95kg and a rear pannier.

I am just over 2/3 your weight and run 32s even lower. I run 55 rear and 50 front, have done for 5 years and would no dream of going over 60.

 

[Mburton1993]

Do you mean you’re rounding off the Allen key? This can be due to dirt collecting in the bolt holes causing the key not to locate properly. Always a good idea to clean them out and and give the Allen key a good tap to make sure it’s home. Never had a problem.

Yes that, cheers, I think I'll be cleaning them out after every ride in the future.

 

[Ming the Merciless]

That Jarno Bierman fella loves his empirical data at BRR
https://www.bicyclerollingresistance.com/specials/conti-gp4000s-ii-23-25-28
Not for the faint hearted, but has he really tested all those tires? (sic)

You have to be careful with his tour tyre results. He will often test at a pressure you wouldn’t run the width of tyre at. For instance he tests a 37mm tyre at 75 psi. So the rolling resistance figures he quotes will be lower than you’ll get when running at reasonable pressures for the width. So the gap between road tyres and tour tyres may be greater than his tests imply.

 

[Grant Fondo]

You have to be careful with his tour tyre results. He will often test at a pressure you wouldn’t run the width of tyre at. For instance he tests a 37mm tyre at 75 psi. So the rolling resistance figures he quotes will be lower than you’ll get when running at reasonable pressures for the width. So the gap between road tyres and tour tyres may be greater than his tests imply.

Yeah that sounds daft. I was putting around 60 psi in 38c Sawtooths and that felt too much.

 

[Ming the Merciless]

Marathon Supreme quoted at 19.1 watts, which is the 60 psi figure for 37mm width. Let’s say you get the 32mm version and run at 60 psi, which is 15% drop if your weight is in the 70-80kg range, and feels about right.

Using the Marathon Greenguard super test as a guide the rolling resistance of 32mm Supreme at 60 psi will be about 23 watts not 19 watts. A mid range 32mm road tyre at 60 psi will deliver rolling resistance about 14-15 watts. So you are adding 8-9 watts rolling resistance per tyre. That’s the equivalent of about 1 mile per hour slower due to rolling resistance.

Rolling resistance and speed isn’t everything. But if you are on that site I’d presume the person would have some interest in the relative difference it may make to speed.