'Upgrading' to skinny tyres pointless for London commuting

But by having a smaller contact area tyres are less likely to encounter debris in the first place. Which means larger tyres are not less likely to puncture.

You need to factor in the weight, 80kg in says a 5mm square contact point vs. 80kg in a 1cm square - which would you reckon spread the weight evenly?

Also don't forget the psi difference, 28c at 75psi vs. 23c at 100psi.

Pressure = force per unit area

Bigger tyre = bigger contact patch

Assuming minimal difference in weight when switching to bigger tyres then the pressure applied on the road surface by the tyres decreases, meaning that when you hit something sharp there is less force acting on it to push it into the tyre, meaning you're less likely to get a puncture.

This doesn't take into account the likelihood of the large contact patch picking up more debris though, you'd have to calculate the ratio of decrease in pressure on the road to likelihood of hitting something on the road due to increased contact patch for a given raise in tyre size to come out with a useable answer as to whether increasing tyre size actually reduces the risk of a puncture.

^ this.

I can't explain for shit.

But is it raining?

Bigger area, more crap, lower poking through force; smaller area, less crap, more poking through force.

This works for me. Probably trying too hard to factor in the probability of actually hitting anything in the first place.

The poking in threshold doesn't vary with width though, so less force = much better than less crap. Maybe.

http://www.bikequarterly.com/images/TireDrop.pdf

Also: grip. I switched a front armadillo for a gatorskin after one too many 'interesting' slides across drain covers.

^ cool story.

I bet there's a strong correlation between people who pump to the max and people who make sweeping statements about X tyre being shit in the wet.

Idiots.

I pump to the max and bonty hardcases are rubbish in the wet

I pump to the max

Yuck. I've just had my lunch.

:-]

An image for all occasions, just in case anyone needs it.

this.

I like turtles

You need to factor in the weight

I did.

The likelihood of being punctured should remain the same, in this particular paradigm.

That. There are so many other variables though, rider weight, tyre design (a huge factor). And so on and so on ad infinitum.

And if skinnier tyres pose a higher risk for pokes:

The advantage is, though, that you can keep an eye out and 'squeeeeeeze' through pointy debris.

Btw, did check my tyres for little glass eaters making there way through. There where some to be found! More in the front than the back though.
Note to self: check that more often.

Pump to the max and HTFU if it hurts your ass.

Balki would fuck you in a game of pump.

Wait a sec...

I'd pump you in a game of...

Is this getting out of hand?

This is a laugh isn't it.
Am I in the minority by using 23mm tyres pumped up every week to their 120psi max whatever the weather?

pretty much what I do, except more time in between pumps as i'm a bit lazy

Looking more likely that you are both in the ignorant majority - no offence.

Without giving any thought or seeing any data/evidence behind different pressures and width it is easy to assume that narrow and hard must be faster and it always will be in the extremes (comparing a 140g 20c at 140PSI with a 1200g 100c at 30psi)
It is only when comparing 23c with 28c that it becomes less obvious.

Anything close to 100psi is definite pinch-flat territory for me. Only at above 120psi do I feel remotely confident when on the bike.

I'm with the ignorant majority also. I should get a t-shirt for this. :-)

I am trying 27c (but look larger) at 60psi for the club run tomorrow, just to join in with the cool kids and their fancy fat soft tyres

No offence taken, I like learning stuff. Can someone please precis this tedious thread into one sentence? What tyre "should" I be using?

Onza Porcupines

Skinner smaller tyres have less contact point so says 80kg will be on that tiny area thus more likely to get sharp debris embedded.

http://en.wikipedia.org/wiki/Newton's_laws_of_motion#Newton.27s_third_law

At the contact patch, the tread of the tire is flattened against the road. Air pressure can only push directly outward, and so here, it pushes directly downward. The downward force of the air must equal the weight load, and so the area of the contact patch approximately equals the weight load divided by the air pressure. (Edge effects and skewing of the weave of the fabric may result in some difference.)

Notice that the above quote mentions only the weight loading the tyre, and the pressure of the tyre. This is what defines the overall size of the contact point.

Specialized romin.