Cycling UK Forum

Tyres? They go on the rims, get air into them then ride. You're not Chris Froome long for marginal gains to win a tour. You're possibly a middle aged bloke who loves riding for leisure. Just try a few tyres out, play with the pressure until you find something you're happy with. Then just keep buying it until the tyre company improves it so much it no longer suits you. Rinse and repeat!

Why do people like to debate to the nth degree of topics like tyres? I would suspect that if you notice any significant difference in performance between tyres it's probably mostly in your mind.

Rgrds
Cynical person.

Tangled Metal wrote: I would suspect that if you notice any significant difference in performance between tyres it's probably mostly in your mind.

Rgrds
Cynical person.

I bet I could give you two outwardly similar tyres that you could detect a real difference between. I remember trying Schwalbe Duranos and hating them because the ride was harsh at a pressure I wouldn't want to go below because I value my wheel rims. Grand Prix 4 Seasons in roughly the same size were definitely smoother riding over the chip n seal tarmac that graces my street.

But I agree that one should play around with tyre pressures to optimise the ride.

pwa wrote:

Tangled Metal wrote: I would suspect that if you notice any significant difference in performance between tyres it's probably mostly in your mind.

Rgrds
Cynical person.

I bet I could give you two outwardly similar tyres that you could detect a real difference between. I remember trying Schwalbe Duranos and hating them because the ride was harsh at a pressure I wouldn't want to go below because I value my wheel rims. Grand Prix 4 Seasons in roughly the same size were definitely smoother riding over the chip n seal tarmac that graces my street.

But I agree that one should play around with tyre pressures to optimise the ride.

OK prove it! I'll pm my address to send the free, I mean test, duranos and GP4Seasons for me to test to destruction.

pwa wrote:

Brucey wrote:gravity doesn't work like that; the force is in proportion to the weight and the acceleration is constant.

cheers

Yes, to be clear what I am saying is that while we might expect a heavier object to accelerate faster, inertia means it doesn't, .

This is a confusing way of thinking about it. Gravity is a force that is proportional to the mass, therefore constant acceleration should be assumed unless you do something weird. As in many physics problems there is a clue in the units; 'g' can be expressed in units of


force per unit mass (N/kg)

or

acceleration (m/s^2)

which are in fact equivalent to one another, i.e. N/kg = m/s^2. It can sometimes help to think off different units in different problems.

The fact that, when dropped, the terminal velocity of a ping pong ball and a steel ball of the same size are different is absolutely nothing to do with inertia and everything to do with the fact that the forces acting on each are different.

cheers

Tangled Metal wrote:!Why do people like to debate to the nth degree of topics like tyres?

Because there's a whole world spectrum of difference across the tyre range,if you ride say a Marathon Plus with Vittoria Voyager Hyper of the same size it becomes immediately obvious,of course the M+ offers better puncture resistance than the Hyper and if you use the bike for short journeys on glass strewn streets and cyclepaths comm in most inner cities then M+ wins out,but for longer rides where comfort and effort are to be minimised the Hyper is unbeatable IME.

I would suspect that if you notice any significant difference in performance between tyres it's probably mostly in your mind.

Rgrds
Cynical person.

I'd suggest that depends on the person and the tyre,but numbers don't lie.
I've done the tests,weighed up the numbers and reached conclusions on those tests and numbers.
It's my experience that on roads which are mainly chip n seal and rough tarmac potholes an all,a larger section supple tyre like Hypers ride far more comfortably than narrow high pressure tyres,they corner better and are more sure footed and can descend far faster.
Overall any loss of speed is very minimal,according to my numbers and tests within 1mph over a set 70mile course even though the bike with large section 40mm(37mm actual) tyres fitted was 2kg heavier than the bike fitted with 28mm(26mm actual)HP tyres.
I've also found that the wider tyres cut less though don't puncture any less(for me a couple of punctures a 7k mile year is about normal with 4 punctures being a bad year)and last in the region of 50% longer than HP tyres.The other obvious plus is that they'll tackle offroad bits without the need to worry about slowing up to much on gravel or hard pack trails and towpaths.

How much difference does tyre width make? That was the question in the OP. And from personal experience I can say that if you are talking about a 3mm jump from 25mm to 28mm the answer is "a bit but not a lot". I have ridden 25mm and 28mm on the 90 mile Gospel Pass Audax from Chepstow and while I thought I could feel a difference it was small and my time for the ride, and my knackeredness at the end, was about the same. A slightly smoother ride with 28mm but easier climbing with 25mm. And why would anyone expect 3mm to make a big difference?

Numbers don't lie but you can't feel numbers on a bike. OP asked about width between 23 to 32mm. One end to the other you'll probably notice comfort if you run at bear pressure for you and the tyre width. But tbh what is it you're feeling? A load of different factors with their own measurable numbers that make absolutely no difference. It's binary. Try it out, if you play around with width, pressure, etc you'll find something you like. It's that binary, you like it or you don't. It feels good or it doesn't.

As soon as you have the feel good does the speed matter that much? Your speed probably has more to do with you than the tyres. Unless you're a competitive cyclist does it really matter that you get those marginal gains when comfort might be more important?

Tangled Metal wrote:Numbers don't lie but you can't feel numbers on a bike. OP asked about width between 23 to 32mm. One end to the other you'll probably notice comfort if you run at bear pressure for you and the tyre width. But tbh what is it you're feeling? A load of different factors with their own measurable numbers that make absolutely no difference. It's binary. Try it out, if you play around with width, pressure, etc you'll find something you like. It's that binary, you like it or you don't. It feels good or it doesn't.

As soon as you have the feel good does the speed matter that much? Your speed probably has more to do with you than the tyres.

Rubbish!
And I have tried it out,numerous times and with quite a few different tyres.

Unless you're a competitive cyclist does it really matter that you get those marginal gains when comfort might be more important

That depends on a few things but mainly mileage per ride.

Brucey wrote:

pwa wrote:

Brucey wrote:gravity doesn't work like that; the force is in proportion to the weight and the acceleration is constant.

cheers

Yes, to be clear what I am saying is that while we might expect a heavier object to accelerate faster, inertia means it doesn't, .

This is a confusing way of thinking about it. Gravity is a force that is proportional to the mass, therefore constant acceleration should be assumed unless you do something weird. As in many physics problems there is a clue in the units; 'g' can be expressed in units of


force per unit mass (N/kg)

or

acceleration (m/s^2)

which are in fact equivalent to one another, i.e. N/kg = m/s^2. It can sometimes help to think off different units in different problems.

The fact that, when dropped, the terminal velocity of a ping pong ball and a steel ball of the same size are different is absolutely nothing to do with inertia and everything to do with the fact that the forces acting on each are different.

cheers

This is one cycling phenomenon (heavier riders accelerate downhill faster than lighweight riders when neither pedal) that's always defeated my admittedly basic knowledge of physics. In a vacuum, all weights of objects fall at the same (change of) rate. As we're dragged at by air and road when on a bike, surely the descending differentials should be to do with the cyclist's frontal area and tyre choice, not body weight....?

Yet a bigger lad with broad shoulders would surely have a greater frontal area (and thus air-drag) than a skinny wee lass.......?

There are a lot of factors involved. Well, more than two. Is the three body problem raising it's awkward head?

Cugel

I think a lot of us just know, from experience, that the skinny riders who fly up hills tend to lose a bit of ground going down the other side to those carrying a bit more weight. One factor may be that heavier riders are a bit more aero per Kg than skinny riders. So being bigger doesn't translate into all that much more frontal area.

pwa wrote:….So being bigger doesn't translate into all that much more frontal area.

agreed; Belgiangoth made the point that something larger and heavier gathers weight as the cube but surface area (aero drag) as the square. This is true if the two things have the same proportions, but in reality this is often not the case; when many people put on weight they tend to what is best described as an 'oblate spheroid' in shape. This means that the aero drag per kg is liable to be even less than you might expect.

cheers

This begs the question "Is there an aero advantage to being a big lad?"

Mostly psychological, a wide tyre looks. Slower and heavier than a skinny one. And as those cyclists who are in the racing mind set will spend billions for that extra gram saved, then wide Tyres are become Satan's anchor.

NEvans wrote:A make/model such as the Continental Grand Prix 4 Season 700C Duraskin Tyre comes in four different sizes: 32c, 28c, 25c, and 23c. Opinion would be about a playoff between weight and comfort. My general thought would be to go for the 28c for some comfort and durability, but is there much difference between them?

9mm .
Or not much difference.

P.S. 4 pages of "Debate"! & no agreement.

pwa wrote:

The utility cyclist wrote:

Brucey wrote:whenever you go downhill, weight is the most important thing; basically you have a gravity engine and the power is pro-rata with weight. Next comes aerodynamics (moreso at speed), then rolling resistance.

Things like bearings need to be very knackered or badly adjusted indeed before they make an appreciable difference.

cheers

Is it, explain how? If I'm sat up with a billowy jacket, someone 20kg lighter than me with a smaller frontal area and decently snug outer garment plus aero position will absolutely go past me on a downhill, I'm at odds with your theory, please post your findings as to how you came to such a discovery.

In theory if you have two objects of the same shape and volume but different mass, inertia will slow down the acceleration of the heavier object, so it will not have that much of an advantage on descending initially, but once it gets going it will carry the speed further as the slope eases because of the advantage that mass gives via momentum. I find that when I ride with lighter family members I have to sit up on descents to avoid leaving them behind.

We're not talking about when the slope eases though and your point about sitting up proves my point does it not, aero is king when on descents which is when the speed is higher, weight, as Brucey stated is not the most important thing.