How did we delude ourselves about 23mm?

[amediasatex]

It's that I don't feel any discomfort with bumps and road buzz

Discomfort or not is not really the point, people can put up with discomfort but vibration does fatigue you and when extreme can also physically slow you down in an immediate sense both through attenuation/energy dissipation and also by limiting your power output.

Fair enough, although too time consuming to compare many combinations of tyres and pressures.
Since you presumably have a power meter, have you tried Robert Chungs method?
http://anonymous.coward.free.fr/wattage/cda/indirect-cda.pdf

No, I have not, thank you for the link, I'll have a read

[Mick F]

Define Road Buzz?

It seems to me that people "suffer" from it. They don't like it and it hurts them.
I say I can feel the road, but it's not a buzz.

Buzz to me, is the sort of thing that could give you a sort of vibration numbness?
Nothing of the sort for me.
No specific buzz, but I can feel the road of course.

[reohn2]

Define Road Buzz?

It seems to me that people "suffer" from it. They don't like it and it hurts them.
I say I can feel the road, but it's not a buzz.

Buzz to me, is the sort of thing that could give you a sort of vibration numbness?
Nothing of the sort for me.
No specific buzz, but I can feel the road of course.

You posted:-

It's that I don't feel any discomfort with bumps and road buzz. Bumps, depending on what they are of course

Which seems to indicate you're aware of what road buzz(otherwise known as HFV)is.

[amediasatex]

Buzz to me, is the sort of thing that could give you a sort of vibration numbness?

It doesn't need to be extreme enough to cause numbness, and I think 'hurt' is also too strong a word.

The buzz and vibration you feel from the road, which can be worse on some surfaces and at some speeds, all that vibration and jiggling you around has an effect beyond discomfort, even at a level where you might not 'notice' it, it's still having an effect.

There's considerable energy involved over the course of a ride, we've all felt the difference between a smooth bit of new tarmac and then when you join a rough bit (or vice versa), it doesn't 'hurt', and after a few moments you don't consciously continue to notice it, but the extra buzz and vibration is still there.

[reohn2]

Buzz to me, is the sort of thing that could give you a sort of vibration numbness?

It doesn't need to be extreme enough to cause numbness, and I think 'hurt' is also too strong a word.

The buzz and vibration you feel from the road, which can be worse on some surfaces and at some speeds, all that vibration and jiggling you around has an effect beyond discomfort, even at a level where you might not 'notice' it, it's still having an effect.

There's considerable energy involved over the course of a ride, we've all felt the difference between a smooth bit of new tarmac and then when you join a rough bit (or vice versa), it doesn't 'hurt', and after a few moments you don't consciously continue to notice it, but the extra buzz and vibration is still there.

A good description,road buzz is nice when it's "switched" off and the difference between say chip n seal and smooth tarmac.

[whoof]

I found this, it's claims to show the tyre width used by each of the teams in last year's Tour de France. No 23 mm tyres but no 28mm + ones either.
All were 25 mm, except a couple of teams on Specialized which were 26 mm.
https://www.bikeradar.com/road/gear/art ... nce-50337/

[Mick F]

Sorry.
I do not suffer from what is described.

I can feel the difference between a smooth road and a chip+seal one of course.
No buzz, but vibration perhaps on less smooth roads.
No jiggling unless on very rough lanes, but never on roads.

[reohn2]

Sorry.
I do not suffer from what is described.

I can feel the difference between a smooth road and a chip+seal one of course.
No buzz, but vibration perhaps on less smooth roads.
No jiggling unless on very rough lanes, but never on roads.

You're describing road buzz or HFV,the fact that you can tolerate it perhaps suggests you're in good shape(which I don't doubt),but nevertheless it's there.
The same sensations someone may not find tolerable for a various reasons,mine is soft hands and Osteoarthritis in hands,wrists,neck,and shoulders,particularly my left shoulder,and my back.My doctor says it's wear and tear and what's to be expected after 50 years of hard labour.
Whatever it's there and it gives me gyp.
Big supple tyres at low pressures help considerably with not much loss of speed.
As I posted on another thread a light bike with the clearances for the same wide tyres, the right geometry and nice a springy fork for the real big hits would,I suspect,improve climbing,be about the same on the flat or maybe slightly quicker,and would sail away from any bike with narrow HP tyres,on the rough descents bad roads offer.

As an aside,today we drove out to a cafe we used to ride to on the tandem,taking a very similar route which we hadn't been on for while.I was alarmed and taken aback not only by the very poor state of the back lanes,but also by the sections of the A49 we drove on. I can only see the lanes being neglected more,in favour of any arterial routes taking any maintenance money available to councils near and wide

[Scunnered]

My experience tells me I’m as good as anyone at observing small changes (for example, I can just about feel the drag when I turn on my dynamo lights), but I don’t have any illusions about reliably detecting even significant changes in rolling resistance by going for a ride.

Agree with all of your post.
To put rolling resistance into perspective, a top tyre eg GP TT has a Crr = 0.003
The effect of that Crr is equivalent to riding up a slope of 0.003 (i.e. 3m in every km) on tyres with Crr = 0
That is not a negligible effect, but I doubt anyone can 'feel' a difference of say 0.001
You can feel vibrations but that is a different quantity altogether.

[atoz]

I'll wait for the nay sayers.

Here I am!

I'm more than happy with my 23mm Vittoria Rubino Pro Slicks.
I was happy with the 20mm versions but I suffered from pinch punctures once or twice as they were a bit narrow for the rims. 23mm are perfect and when they wear out, I'll be buying more.

It's all to do with the bike IMHO, not the width of the tyre per se. I have a nice and light and springy old fashioned 531c Mercian frame of course, and I do not suffer with bounce and roughness. I can compare the ride with a nice and supple suspended Moulton, and although the Moulton absorbs rough bumps and ruts better, the ride isn't much different on normal roads.

There are roads that I prefer Moulton over Mercian, but these are more of the narrow tiny steep rural bumpy badly surfaced variety of roads.
No issues whatsoever with 23mm tyres on Mercian. It's a "road bike" and is ridden on roads.

Still using 23 mm myself, Vittoria Rubino also. It's true, its the bike that makes the difference. My 34 year old CB Brevet is quite comfortable with modern 23's- also one manufacturer's 23 is another''s 25. But I will go over to 25 when the current covers wear out.

[Brucey]

if you want to feel the negative effects of the road surface on speed, just find a rough surface on a gentle downslope, and ride down it (eg coasting) a few times using narrow tyres, pumped up hard, but just sitting on the bike differently. You will find that if you

a) ride sat in the saddle (like a sack of potatoes) with your arms locked rigid and then change to

b) raising one's backside out of the saddle so that the majority of one's weight is supported on the pedals, with a light grip on the handlebars only,

you will go appreciably faster in the latter case. The difference is in the so 'called suspension losses'. There are many shades of grey inbetween, involving fatter tyres, and/or lower tyre pressures, or different ways of sitting on the bike that influence whether the bike works as part of the sprung or unsprung weight. Note that quite small differences in speed may represent quite large changes in the losses, depending on how much aero drag there is.

Not that I think it is remotely representative of any kind of normal riding, but Jan Heine has ridden down rumble strips at speed and reckoned that with skinny tyres it might cost you 300W or so, but nothing like so much with fat tyres. On a local TT course I used to ride regularly, there were concrete edging stones by the side of the road. In parts this left a very smooth surface about 7" wide that you could ride on, if you concentrated hard. I reckoned it was worth about 0.5mph over the less smooth parts of the main carriageway, in other places where the road surface was a bit smoother anyway, a fair bit less.

BTW an obvious practical point is that if you ride on (normal) bumpy roads, have mudguards on your bike, and you like them, you may as well choose your next set of tyres to be as wide as the mudguards are, more or less; you may get an aero benefit (over skinnier tyres under mudguards of the same width) as well as an effective Crr reduction.

On a bike without mudguards fitted it is less clear what is the best thing to do; much fatter tyres may roll easy at low speeds on bad surfaces but may result in a net loss of speed due to the poorer aerodynamics when you are riding on average surfaces.

cheers

[pwa]

The crucial speed comparison for me is not so much somebody's Rolling Resistance figure (though that must feed into my experience) but how easy I find it to propel my bike up small climbs. The climbs that with a small surge of effort you can get over in thirty seconds without losing too much speed.
https://www.google.com/maps/@51.4576351 ... 6?hl=en-GB

This nondescript piece of road has a good example of that. The pic flattens it out, but you have a drop for fifty metres, short flat bit, then a short medium steep climb for fifty metres, all on tarmac that is unreliable and needs watching. On 35mm Hypers I watch the tarmac a bit less, but when I get to the climb my speed drops more than it does on 25mm GP 4 Seasons. I end up in lower gears. And not appreciably more comfy. Both tyres do a decent job of taking out small hits. Neither tyre kills road buzz completely, and that is with them inflated to the lowest pressure at which the tyre supports my weight and doesn't deform in unwanted ways. I'm happy with either tyre. The Hypers allow me to be less careful, the GP4Ss allow me to crest those micro hills with less effort.

[pwa]

I'm not convinced that Rolling Resistance tells the whole story. Tyres are suspension. Big tyres at lower pressures have more suspension than narrower tyres at higher pressure. What happens when you pedal hard uphill on a bike with suspension? Especially if that suspension is crude. You bounce. Some of the energy you put into the pedals bounces the bike instead of propelling it forwards. I can feel that with big soft tyres.

[Brucey]

I agree there is an effect there. As well as the possible bouncing there is carcass deformation to consider. I've seen very many MTB rear tyre carcasses fail by being sheared too much, which mainly occurs when the torque through the wheel is very large. The shearing process is likely to be very lossy. Any kind of intense effort on a road bike will impose similar stresses on a fat tyre and is likely to cause similarly large losses.

cheers

[mig]

if you want to feel the negative effects of the road surface on speed, just find a rough surface on a gentle downslope, and ride down it (eg coasting) a few times using narrow tyres, pumped up hard, but just sitting on the bike differently. You will find that if you

a) ride sat in the saddle (like a sack of potatoes) with your arms locked rigid and then change to

b) raising one's backside out of the saddle so that the majority of one's weight is supported on the pedals, with a light grip on the handlebars only,

you will go appreciably faster in the latter case. The difference is in the so 'called suspension losses'. There are many shades of grey inbetween, involving fatter tyres, and/or lower tyre pressures, or different ways of sitting on the bike that influence whether the bike works as part of the sprung or unsprung weight. Note that quite small differences in speed may represent quite large changes in the losses, depending on how much aero drag there is.

Not that I think it is remotely representative of any kind of normal riding, but Jan Heine has ridden down rumble strips at speed and reckoned that with skinny tyres it might cost you 300W or so, but nothing like so much with fat tyres. On a local TT course I used to ride regularly, there were concrete edging stones by the side of the road. In parts this left a very smooth surface about 7" wide that you could ride on, if you concentrated hard. I reckoned it was worth about 0.5mph over the less smooth parts of the main carriageway, in other places where the road surface was a bit smoother anyway, a fair bit less.

BTW an obvious practical point is that if you ride on (normal) bumpy roads, have mudguards on your bike, and you like them, you may as well choose your next set of tyres to be as wide as the mudguards are, more or less; you may get an aero benefit (over skinnier tyres under mudguards of the same width) as well as an effective Crr reduction.

On a bike without mudguards fitted it is less clear what is the best thing to do; much fatter tyres may roll easy at low speeds on bad surfaces but may result in a net loss of speed due to the poorer aerodynamics when you are riding on average surfaces.

cheers

the origins of marginal gains!