MTB slick tyres and town bikes

dazzawazza

My comments are for tarmac riding.
I've got 1.0" Specialized All Condition Pros on my MTB commuter and they are faster than the previous Maxis Detonator 1.5" tyres. They handle better in the dry and puncture much less too.
The 1.0" tyres are probably made of better materials and are at 115-120PSI.
The 1.5" tyres had better braking and grip in the wet, however I prefer the speed and handling in the dry.
So I guess the preference is dependent on what the rider prefers.
Another consideration is that generally it's dry during a commute more than wet.

dazzawazza

Doubleup so deleted

m0scs

omg! I bet you wished you never asked.

Fwiw I run conti ultra gators 1.25 in width on my MTB at about100psi. They are fast, puncture restistant but don't last as long as spec nimbus armadillos

comfort is a secondary issue for me. The 1.5spec nimbus give a much softer rider and also give good puncture protection. I had the contact sport for a short while but they don't give the puncture protection of the other two.

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meanwhile

roger merriman wrote:

meanwhile wrote:

It's pretty clear that you still don't understand what was actually said...

read that PDF, read this part.

Why do Pros ride narrow tires if wide
tires roll better?
Wide tires only roll better at the same inflation pressure,
but narrow tires can be inflated to higher pressures than
wide tires. However, they then obviously give a less
comfortable ride.
In addition to this, narrow tires have an advantage over
wide ones at higher speeds, as they provide less air
resistance.
Above all, a bicycle with narrow tires is much easier to
accelerate because the rotating mass of the wheels is
lower and the bicycle is much more agile.
At constant speeds of around 20 km/h, the ride is better
with wider tires. In practice, the energy saving is even
greater than in theory as the elasticity of the tires
absorbs road shocks, which would otherwise be trans-
ferred to the rider and so saves energy.

ie for a given PSI wider is faster but, and this is why the trend is for thin = faster is that for a given tire thinner tires will take higher PSI.

Congratulations on achieving PARTIAL understanding - which is about all that can be expected if you only read PART of what I quoted. What your brain has failed to cope with is that the above explains why roadies ride narrower tyres even though they have more RR than wider ones made of the same rubber: see the preceding section.

You've also failed to understand what the part I've put in italics means: energy saving = more speed.

Ultremo R comes in 23mm (145PSI) 25mm (115PSI).

in practice thinner tires are faster simply because they can be pumped up to very high pressures.

Yes, that's what you think. But what you think doesn't matter. The docs and empirical data are clear: at speeds below around 25mph, the wider fast rubber tyres save energy - at the cost of burning more energy at higher speeds.

The problem here is that you just don't understand basic bike physics: the most efficient hardware for utilizing 100-200W commuting power is not the same as that for utilizing 400-1000W racing power, because the balance between rr and aero is different. I doubt, in fact, if you understand any of the basic characteristics of the stuff you spend money on - you certainly have mentioned the speed-power laws which would make the energy savings you imagine lower tyres provide idiotic to aim for outside of racing...

You might find the source I quoted more readable - and someone who can't tell the difference between 12mph and 25mph certainly needs help:

http://www.rouesartisanales.over-blog.c ... 03651.html

"Narrower tires of 23 mm and less, decrease rolling performance and require higher inflation pressures, which adversely effect riding comfort. Gains are made in aerodynamics requiring less energy for maintaining speeds exceeding 40 km/h or 25 mph."

- And that's with road rider rather than commuter type weights. Add more weight to the system and the critical width gets wider, which is the 28mm had the lowest RR in the data set I linked to, even though it was a tyre with less emphasis on performance, so it will have had thicker walls, etc, all increasing rr.

meanwhile

Understanding documents written by German engineers for people as smart and anal retentive as themselves is a bit tricky, so I'll make this really simple: take a look at this graph-

http://www.terrymorse.com/bike/imgs/rolres.gif

The lowest rr tyre in the whole data set is the 28mm training-touring tyre. That's despite the fact that it will have more thickness to increase durability, which is a factor that itself increases rr. It's lower rr than any of the premium racing tyres it is tested against, despite the fact that they will have traded off tyre lifetime, comfort, puncture protection, and cost to get speed.

Why? Because wider -within reason - is lower rr. The other tyres are still faster in the circumstances of a race - because in a race aero and the ability to accelerate marginally faster out of a corner to take position - dominate. Faster for racing isn't necessarily faster for commuting!

The bicycle industry makes a fortune from people silly enough to follow cargo-cult theories of speed and bicycle design. Specialized's board meetings must collapse in incredulous laughter sometimes at the idea that their best customers still believe that bicycles lose energy to frame flex...