How much pressure?

[S-Express]

Another explanation of the same 'black magic, wizardry and general heresy' here: https://cyclingtips.com/2009/03/what-is-the-optimal-tyre-pressure/

 

[Ajax Bay]

How much pressure should I have in the tyres on my hybrid bike when carrying fully laden panniers (for example on my coast to coast cycle?)

Realise that in my Post #25 (hope useful) I did not directly answer Q3 (above).

Rider plus bike is 73kg + (say) 12kg for the Specialized Sirrus Sport hybrid plus 15kg in the panniers = total load 100kg.
Taking a load split of 35% front, 65% rear (assume rear panniers only, bar bag will make little difference as not filled with heavy stuff) (NB see article), gives 35kg/65kg for the Sirrus (32mm wide tyres). From the graph on the BQ authority article F 45psi R 84psi. If you want to stay in the quoted range for the M+ on the front, make that 50psi.

 

[S-Express]

You'd have more luck with a brick wall tbh.

How's that wall coming on..?

Another article on the same: http://triathlete-europe.competitor.com/2011/05/03/facts-figures-myths-optimum-tyre-pressure

I know they're triathletes, but we can forgive them for now..

 

[Ajax Bay]

Here's an interesting article from Hunt, which does describe the issue better. https://www.huntbikewheels.com/pages/recommended-tyre-pressures

Pretty useless article imo. Hunt give no rationale for their recommendations or their front rear split. You can work out your front rear split (help needed) by getting on your bike, putting the (bathroom) scales beneath each wheel in turn, being supported adopt your 'riding position' of choice (eg on the hoods) and reading off the results. The BQ article which I attached in my post #25 gives the 'normal' splits for the different types of rider (randonneur, racing, city).
The other article quoted https://cyclingtips.com/2009/03/what-is-the-optimal-tyre-pressure/ has a better discussion of the issue, but then goes Aussy-wishy-washy over pressure recommendations.
Jan Heine's article "tire-pressure-take-home"

 

[mark st1]

How's that wall coming on..?

Another article on the same: http://triathlete-europe.competitor.com/2011/05/03/facts-figures-myths-optimum-tyre-pressure

I know they're triathletes, but we can forgive them for now..

I've no doubt you know your stuff but your attitude sucks shoot. You talk to people like shoot and you come across just wrong on an internet based forum. I'm yet to have the pleasure to meet you in real life so I'd like to give you the benefit of the doubt. 99.9 % positive this isn't your first account on this forum though

 

[Ajax Bay]

You'd have more luck with a brick wall tbh.

I note the forthright activity you have managed to elicit with your 'wall' assertion and shall try that with @S-Express in future. You have done much better than I did in the 'road buzz' thread. Having tossed the 'just google it' your way, he's found some stuff, some useful, some not, and shared it.
Hope you get out for a ride tomorrow.

 

[Ajax Bay]

I've no doubt you know your stuff

Credit where credit's due, please.

 

[S-Express]

I've no doubt you know your stuff but your attitude sucks shoot. You talk to people like shoot and you come across just wrong on an internet based forum. I'm yet to have the pleasure to meet you in real life so I'd like to give you the benefit of the doubt. 99.9 % positive this isn't your first account on this forum though

The thing is mate - I'm not here to be your friend - or anyone elses. Ironically, your responses to me have been far more discourteous than any reply I have posted on this thread, including your initial post, which was nothing more than an ad hominem which added nothing. People asked for clarification of my earlier comments and that is exactly what I am providing. Do me a favour - go out for a ride tomorrow around the lanes of 'leafy Berkshire' (I know it well) with your tyres inflated to 150psi - hopefully your dentures will fall out.

 

[User6179]

and @r04DiE
This article gives some useful arguments (if not data) on which @S-Express may be drawing (albeit with careless phrasing), and I recommend it to you. The main argument is that by running wider tyres at lower pressures you reduce the suspension losses in the rider/bike combo and thus real rolling resistance is reduced. On a smooth drum (ie the rollingresistance.com tests) rollingresistance reduces very slightly as the pressure on the same tyre is increased - but this higher pressure results in more, for want of a better word, 'bouncing' on rough surfaces (eg roads) which actually means a narrower tyre at higher pressure (to avoid pinch flats) is 'slower'. Edit: this may be @S-Express "in many cases' ie not on tracks.

At higher speeds (eg 45+kph) aero aspects may come into play, and wider tyres tend to be heavier (which may be an issue if lots of acceleration involved - as opposed to steady riding). It would be excellent if tyre manufacturers of the good road tyres (Michelin, Continental, Vittoria, Schwalbe et al) made 28s which measured 28 and 32s in the same 'road tyre' range, as opposed to the step across (ie not up) to the fastest but heavier 'touring' tyres eg M Supremes.

They tested 3 CX tyres and none of them were faster at lower pressures , they said they were the same .

 

[S-Express]

They tested 3 CX tyres and none of them were faster at lower pressures , they said they were the same .

Nobody is saying that tyres are routinely faster at lower pressures though.

 

[Ajax Bay]

Nobody is saying that tyres are routinely faster at lower pressures though.

Oh yes they are! Common knowledge - just google it.
Edit: Depends what you mean by 'routinely' and 'lower'.

 

[User6179]

Nobody is saying that tyres are routinely faster at lower pressures though.

 

[Ajax Bay]

From the Jan Heine article:

• "On rough roads, lower pressures are faster. So if you want to optimize your speed on all roads, including rough ones, go with a relatively low, but safe, pressure.
• "Your tire pressure needs to be high enough to avoid pinch flats. If you get pinch flats, increase your tire pressure, or better, choose wider tires.

"It can be hard to believe this, because higher pressure feels faster. Here is why: When you go faster, your bike hits more road irregularities per second: The road buzz increases in frequency. Most cyclists know: higher speed = higher frequency. Higher tire pressure cheats you into thinking that you are going faster, because it also increases the frequency of the vibrations: higher pressure = higher frequency. It’s natural to assume that this means: higher pressure = higher frequency = higher speed, but that is incorrect. Instead, you are looking at two different mechanisms that both increase the frequency of the road buzz. Even after years of riding supple, wide tires, this “placebo” effect sometimes plays tricks on me. A supple tire absorbs vibrations better, so it can feel slower – until you look at your speedometer."

 

[S-Express]

Oh yes they are! Common knowledge - just google it.

Er - no they're not. No need to google it.

Edit: Depends what you mean by 'routinely' and 'lower'.

You can google 'routinely'. You can also google 'lower' - or you could ask 'eddie', as he originally quoted the word, not me.

Anyway, it's great to see that we all seem to have come to terms with the ground-breaking revelation that 'harder' tyres do not necessarily translate into 'faster' tyres. You can thank me later.

 

[alecstilleyedye]

on my 700x23 vittoria rubino pros (my go-to tyre of choice) i run 120psi at the rear and 100psi at the front. the tyres say 100psi-140psi.

can only speak for my own experience, but punctures are rare and they seem to last 10,000km+ on what is a flat, if pot-holed commute…