Tyre Pressures

wacka

Hi

What are the best tyre pressures for a road bike? I currently run Conti GP4000S 25mm at 95psi for the front and 105psi for the rear. Are these ideal pressures for me as I'm 90kg and is it a good idea to run the back tyre 10psi harder than the front?

Cheers Guys

nanas1

OMG!!!!! I looked at my tyres last night and the pressure ratings stated 105psi on my 23mm tyre.
I pumped it up to 55psi and found that to be rock hard, was scared to go further in case I burst it

kayo74

I'm approx 75kg ride on 23mm GP4000's and put 100psi front and 110psi in rear and works fine with me and very very few punctures in fact can't remember the last one. Regret saying that now!!!!.

declan1

I would recommend 120psi front and rear for your weight (90KG).

nanas1 - trust me you won't burst the tyre. You will probably be able to get it to 200 psi before it bursts from excess pressure. Riding around at 55psi will end up with tons of pinch flats and you'll go slow as hell!

Neil_aky

OK I have posted this a few times before, but rather than opinion, here's the facts:

http://www.michelinbicycletire.com/michelinbicycle/index.cfm?event=airpressure.view

Gizmodo

Another good read is Sheldon Brown
http://sheldonbrown.com/tires.html#pressure

And he refers to an article
http://www.bikequarterly.com/images/TireDrop.pdf

Barteos

Wacka wrote:

Hi
What are the best tyre pressures for a road bike? I currently run Conti GP4000S 25mm at 95psi for the front and 105psi for the rear. Are these ideal pressures for me as I'm 90kg and is it a good idea to run the back tyre 10psi harder than the front?
Cheers Guys

Nothing beats the 15% tyre drop method as a starting point.
It's pretty well researched and unlike dumbed down guides on tyre manufacturers' websites it takes into account load per wheel. With a typical road bike 60/40% weight distribution there is no rational reason to use the same pressure in both tyres.
http://www.biketinker.com/2010/bike-res ... -bicycles/

For a 90kg rider +bike and kit it calculates around 120PSI rear and 80PSI front.




Actually... I'd ignore it altogether and simply go for the lowest pressure you can get away with. Based on the latest research and my own long term experience, on surfaces other than perfectly smooth tarmac lower pressure will make your roll faster. Your brain (and most of forum members) will be telling you something different but a stopwatch is always honest and objective

P.S. For calculations you need the actual not nominal tyre width.

Neil_aky

Nothing beats the 15% tyre drop method as a starting point.
It's pretty well researched and unlike dumbed down guides on tyre manufacturers' websites it takes into account load per wheel. With a typical road bike 60/40% weight distribution there is no rational reason to use the same pressure in both tyres.
http://www.biketinker.com/2010/bike-res ... -bicycles/

For a 90kg rider +bike and kit it calculates around 120PSI rear and 80PSI front.




Actually... I'd ignore it altogether and simply go for the lowest pressure you can get away with. Based on the latest research and my own long term experience, on surfaces other than perfectly smooth tarmac lower pressure will make your roll faster. Your brain (and most of forum members) will be telling you something different but a stopwatch is always honest and objective

P.S. For calculations you need the actual not nominal tyre width.

You say ignore 'dumbed down' manufacturer's sites then give advice which is similar to the Michelin site I quoted...

In order to avoid 'pinch flats' it is a good idea to start with the recommendations from the manufacturer; I agree that you can then experiment from there to get your preferred feel / ride but the manufacturer's recommendation based on your / bike weight is a good start point.

What is irrelevant and confusing to new riders is everyone giving their preferred pressures, I set the pressures on my bike from advice of another rider and only increased my pressure after multiple pinch flats and after reading articles by Sheldon Brown and the 'dumbed down' manufacturer's recommendations.

The US Michelin site I linked to actually has some good articles with a bit of science behind it. I love the way people trust a tyre manufacturer to develop and manufacture the tyre but not be prepared to listen to their advice on pressures!

declan1

madasahattersley wrote:

declan1 wrote:

I would recommend 120psi front and rear for your weight (90KG).

nanas1 - trust me you won't burst the tyre. You will probably be able to get it to 200 psi before it bursts from excess pressure. Riding around at 55psi will end up with tons of pinch flats and you'll go slow as hell!

I'm going to have to call this up. 120 will result in impact punctures in spades and worst of all incredibly poor traction which isn't safe for anyone. I've crashed multiple times on damp corners thanks to people whacking tyre pressures all the way up.

As for the 200psi claim, that's not true on clinchers. I was once riding with someone who had pumped his clinchers up to 130psi. The pressure was so great the the side of the rim exploded, and there was no way he could get home. The taxi cost £50 IIRC

At 90KG, 120psi is most likely not too much. My dad is 83KG and he runs 115-120psi on 23mm tyres all the time. He's never had a problem with grip in any conditions.

Also, I didn't mean you can ride it with 200psi -I'm talking about just when you're pumping it up. Tyres can take (without riding) much more than their max recommended pressure.

Barteos

Neil_aky wrote:

Nothing beats the 15% tyre drop method as a starting point.
It's pretty well researched and unlike dumbed down guides on tyre manufacturers' websites it takes into account load per wheel. With a typical road bike 60/40% weight distribution there is no rational reason to use the same pressure in both tyres.
http://www.biketinker.com/2010/bike-res ... -bicycles/

For a 90kg rider +bike and kit it calculates around 120PSI rear and 80PSI front.




Actually... I'd ignore it altogether and simply go for the lowest pressure you can get away with. Based on the latest research and my own long term experience, on surfaces other than perfectly smooth tarmac lower pressure will make your roll faster. Your brain (and most of forum members) will be telling you something different but a stopwatch is always honest and objective

P.S. For calculations you need the actual not nominal tyre width.

You say ignore 'dumbed down' manufacturer's sites then give advice which is similar to the Michelin site I quoted...

In order to avoid 'pinch flats' it is a good idea to start with the recommendations from the manufacturer; I agree that you can then experiment from there to get your preferred feel / ride but the manufacturer's recommendation based on your / bike weight is a good start point.

What is irrelevant and confusing to new riders is everyone giving their preferred pressures, I set the pressures on my bike from advice of another rider and only increased my pressure after multiple pinch flats and after reading articles by Sheldon Brown and the 'dumbed down' manufacturer's recommendations.

The US Michelin site I linked to actually has some good articles with a bit of science behind it. I love the way people trust a tyre manufacturer to develop and manufacture the tyre but not be prepared to listen to their advice on pressures!

As I said before, manufacturers' guides don't take into account weight distribution but also ignore the weight of the bike and kit.
They are simplified (Does it sound better than dumbed down?) so an average consumer with a 5 second long attention span can understand it.

With a 15% drop calculator you simply type in tyre width and total weight/load per wheel and you get the exact results.

Hoopdriver

120psi makes no sense on the road. You won't improve your rolling resistance, just give yourself a rougher ride and risk impact flats on potholes.

47p2

Nice easy tyre pressure calculator here

warrerj

I've found the Vittoria app to work well for me.
http://www.vittoria.com/en/app/

IT works out at 105psi front and 110psi rear for your weight and tyre type (I always use the wet/rough road conditions as on British roads you never have a smooth road all ride).

plymouthsteve

My Gatorskins roll well and have been resilliant over 000;s of miles at 110psi. I use the same front and rear cos the front is where the weight goes when I'm braking going down hill.

Being used to mtb's and a world of 20-40 psi, it was scary going past the 80 psi mark the 1st time.

In fact, I was indoors with my track pump hose going through the catflap with the wheels outdoors. Wimp.

ednino

I do 80psi front & 90psi rear but im 65kg