Author Topic: Tyre width  (Read 3081 times)

finch

  • Hair today gone tomorrow
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Re: Tyre width
« Reply #25 on: 13 May, 2024, 09:23:47 pm »
25s on my summer bike , but ! They’re on wide rims and come up quite fat 27.5mm to be precise. Also they’re tubeless so less than 80psi. They’re quite comfortable really. The n construction winter bike has 30mm tyres with tubes and they’re definitely a little more compliant. And I currently have a project that’s not quite finished that has luvvvvly 28s which for me is the sweet spot

Re: Tyre width
« Reply #26 on: 13 May, 2024, 10:46:46 pm »
Going back to the discussion on Imperial tyre sizes, it's also worth pointing out that we rarely had any idea what the pressure of our  tyres was. Track pumps were mostly to be found in shops or on Tracks; hence their name.
Measurement was by feel and I do doubt if the pumps we used could  inflate the tyres to anything near the max recommend pressure.

quixoticgeek

  • Mostly Harmless
Re: Tyre width
« Reply #27 on: 14 May, 2024, 02:58:18 am »
Were we wrong in the 1980s to assume 18mm tyres would be faster than wider ones? 

Yes.

J
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Blodwyn Pig

  • what a nice chap
Re: Tyre width
« Reply #28 on: 14 May, 2024, 06:55:01 am »
Grunhilda has 38mm (1.5) Marathon Greenguards front and rear (26” and 20”) , and Olive has, at present a 32mm green guard on the rear and an earlier incarnation of marathon in 28mm on the front. Trying to use up my old tyres, but when you want to, they don’t seem to wear out!  About to refit last summers 35mm Marathon supremes fr and rr to Olive, for the upcoming wee Belgium tour. Those 28mm fronts do seem very harsh tho.

Re: Tyre width
« Reply #29 on: 14 May, 2024, 07:27:53 am »
30-something on my bike (I think I've had from 34 to 38 depending on tyre choice). Because:
It's what the rims were designed for.
I like to get off the tarmac.
I recall feeling decidedly low on comfort and control on 25s once I'd added any weight to the bike and got myself anywhere hilly.
Comfort beats aero for me and the riding I do. I'm not doing this to win or to improve my character.

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rogerzilla

  • When n+1 gets out of hand
Re: Tyre width
« Reply #30 on: 14 May, 2024, 07:50:35 am »
I believe the tyre construction (suppleness) is more important than width.  I tend, unfashionably, towards the narrower end of the range because you can guarantee lighter weight and reduced air resistance, even if RR may be higher than an equivalent tyre of additional width.  Also, narrower tyres are mathematically* less prone to punctures from penetrating objects, all other things being equal. My experience bears this out - I barely ever suffer a visitation.

*they sweep less road width and are less likely to hit a thorn or shard of glass than a wider or lower-pressure tyre

Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Tyre width
« Reply #31 on: 14 May, 2024, 08:23:28 am »
The contact patch of a narrow tyre may be thinner than a wide tyre, but it is longer. It will depend on exact widths, but a narrow tyre could have a larger contact area than a wide tyre...
Those wonderful norks are never far from my thoughts, oh yeah!

Re: Tyre width
« Reply #32 on: 14 May, 2024, 08:36:12 am »
Air resistance of tyres is minor compared to the rider.

rogerzilla

  • When n+1 gets out of hand
Re: Tyre width
« Reply #33 on: 14 May, 2024, 08:38:04 am »
The contact patch of a narrow tyre may be thinner than a wide tyre, but it is longer. It will depend on exact widths, but a narrow tyre could have a larger contact area than a wide tyre...
Yes, but a wider contact patch will still roll over all the same road that a narrow one does, plus more at each side.  The length of the patch is irrelevant to punctures.
Hard work sometimes pays off in the end, but laziness ALWAYS pays off NOW.

Re: Tyre width
« Reply #34 on: 14 May, 2024, 08:44:06 am »
The contact patch of a narrow tyre may be thinner than a wide tyre, but it is longer. It will depend on exact widths, but a narrow tyre could have a larger contact area than a wide tyre...
Yes, but a wider contact patch will still roll over all the same road that a narrow one does, plus more at each side.  The length of the patch is irrelevant to punctures.

Fair point. But is it really significant enough to make a difference?
Those wonderful norks are never far from my thoughts, oh yeah!

Re: Tyre width
« Reply #35 on: 14 May, 2024, 09:05:24 am »
Were we wrong in the 1980s to assume 18mm tyres would be faster than wider ones?

Not necessarily wrong, but the differences between tyres are so small (especially on overall speed) that one may believe whatever fanciful bollocks one likes about why one’s own choice is the best.

Re: Tyre width
« Reply #36 on: 14 May, 2024, 09:34:13 am »
As a teenager in the early 70s I remember riding thousands of miles on my gas-pipe Raleigh Tour of Britain on 27 x 11/4 tanwall tyres.  Wore the buggers right down to the carcass.  I suppose I was commuting and touring.  I recall the combination of steel frame and those tyres providing a comfortable ride, but my youthful body was likely more tolerant of abuse than my present shrivelled husk.  As mentioned upthread, using a simple frame pump I have no idea what pressures I used. Possibly lower than most?

FFWD to 2007 when after a dalliance with mountain bikes I returned to road cycling aged 50.  Bad timing; 23mm tyres were still common and even the Racelight Tk I bought would only take 25s.  5 years later I compounded my blunder by buying one of the CR1-SL frames Wesbtrooks were selling off cheap.  Marvellous frameset but it takes a max of 25mm tyres, and even then the chainstay clearance is so tight I have frequently run a 23 on the rear.

If I was buying a bike tomorrow it would likely have disc brakes and I'd spec 32mm tyres purely for the comfort.  Speed is of no concern to me, but it sounds like they'd be no slower than the 25s...

Re: Tyre width
« Reply #37 on: 14 May, 2024, 10:21:54 am »
Were we wrong in the 1980s to assume 18mm tyres would be faster than wider ones?

Not necessarily wrong, but the differences between tyres are so small (especially on overall speed) that one may believe whatever fanciful bollocks one likes about why one’s own choice is the best.

Empirical measurements say that it isn't fanciful bollocks if you are racing or TT (or indeed, doing audax).

The differences can be many watts. Even tens of watts really adds up over the course of a race.
<i>Marmite slave</i>

Re: Tyre width
« Reply #38 on: 14 May, 2024, 11:25:27 am »
Decathlon - 28mm Conti GP4000, full mudguards
Spa fixed - 28mm Schwalbe One, full mudguards
Elan - 35mm Marathon Surpreme, full mudguards.

The 28mm are quicker than the 35mm. But they have nowhere near the grip of the 35mm, and get easily tram lined by long cracks in the road.

I run full redshift suspension seat post and stem - without those 28mm would be too small: My hands go numb after just 100km.

32mm is my ideal compromise size, but the fixed and decathlon don't have room for that width and run full mudguards.

mcshroom

  • Mushroom
Re: Tyre width
« Reply #39 on: 14 May, 2024, 02:06:00 pm »
Spa Wayfarer - 38mm
Pub bike and CX/gravel bike - 35mm, both set up for roads mainly.
Singlespeed and Road Bike - 25mm

although I've hardly ridden recently as life/family have got in the way.

I prefer the wider tyres at a lower pressure as although they don't feel as fast, because they are smoother, in general the speed (or lack of) is about the same and they are more comfortable. The two bikes with 25s are caliper brakes and 28s are a struggle to fit, especially on the singlespeed with guards.

As well as changing road surfaces and gravel cycling's current enthusiasm, I think there's something to be said for changing geometries and frame properties between the 1980s and now. Bikes are much stiffer than they used to be, especially around the head tube, fork and steerer. I used to have an old 501 road bike from the mid-80s, and that felt relatively smooth even on 23s. The bike had a 1 inch threaded steerer, 26mm bar diameter and quite a relaxed geometry. If you put some work into that bike you could feel the frame flexing.

Compare to my other road bike (a 2014 CF Merida Scultura, which is supposed to be a slightly more endurance focussed bike), which has a beefy head tube (I think it's 1 1/8" - 1 1/4", buit the taper may even be bigger), and a much steeper set of angles. That bike on 25mms feels much harsher, but it also feels more responsive because of the stiffness in the frame. I wonder if some of the migration to larger tyres and lower pressures is to mitigate the other trends towards stiffer less compliant bikes?
Climbs like a sprinter, sprints like a climber!

Re: Tyre width
« Reply #40 on: 14 May, 2024, 05:38:18 pm »
20 years ago I had 28s on my bike because 28 or 32 is what the CTC hive-mind suggested.  I'm on the light side so opted for the slightly sportier version.
Since then I have tried as small as 20 tubulars which were okay and not as tooth jarring as you would think (but still as practical as you would expect tubulars to be; it was an old skool frame so possibly something in what mcshroom suggests) and up to my current 38 tubeless (Override front, G-One at the back after more punctures than I wanted).
I don't go fast enough for that to be important but the comfort is.

On the other biketrike I have whatever size MRaces come in 18" at the front and 28 at the back because I haven't invested in a 650b rear wheel yet.
simplicity, truth, equality, peace

Re: Tyre width
« Reply #41 on: 14 May, 2024, 08:08:22 pm »
Imperial Tyre Sizes.

Just been looking at pics on the Rough Stuff Archive of 27" wheels being taken through the snow and mud.
Assuming they are 27 x 1 1/2, though I am sure I rode 27x 1 3/8s , they do look less wide than modern 32s on 19mm rims

So, assuming I was riding 17mm rims, which I think I was, then I think they come up smaller than a modern type 32mm on 700c 19mm rims.

Re: Tyre width
« Reply #42 on: 14 May, 2024, 08:37:09 pm »
I had 24 x 1 3/8 before 27 x 1 1/4

jwo

Re: Tyre width
« Reply #43 on: 14 May, 2024, 08:52:10 pm »
My oldest (1982 Mercian, 18mm) and newest (2020 Brompton, 32mm) tyre setups.


Re: Tyre width
« Reply #44 on: 15 May, 2024, 06:41:31 am »
Were we wrong in the 1980s to assume 18mm tyres would be faster than wider ones?

Not necessarily wrong, but the differences between tyres are so small (especially on overall speed) that one may believe whatever fanciful bollocks one likes about why one’s own choice is the best.

That just isn't true.

Re: Tyre width
« Reply #45 on: 15 May, 2024, 09:25:38 am »
Two of my bikes have 700x28.  They are audax bikes and I think they are faster than my tourer which 600x1.75"s.  However, the tourer is more comfortable which is very important on the crappy road surfaces we now endure.  Tyres that can iron out more potholes may well be faster, like the tortoise and the hare and I also think that the construction of the tyre might be more important than the width factor. 

Tyres can make a big difference to how much I enjoy the ride, faster or not.

Regarding old frame stiffness, I found a large 531 frame too compliant for hill climbing, 531st is much better. My height and weight is the same as Eddie Merckx was in his day, but there is no other similarity! 
Sheldon Brown never said leave it to the professionals.

HTFB

  • The Monkey and the Plywood Violin
Re: Tyre width
« Reply #46 on: 15 May, 2024, 09:44:26 am »
I've been riding Marathon Plus exclusively since before the millennium. At one point there was a lot of towpath in my life and I was up to 700x38s; now I think they're 700x32 they are 700x35. Tyres that never make you stop and fix a puncture are the quickest of all.
Not especially helpful or mature

Re: Tyre width
« Reply #47 on: 15 May, 2024, 04:45:22 pm »
Yes. They are called tubeless. ;)

ElyDave

  • Royal and Ancient Polar Bear Society member 263583
Re: Tyre width
« Reply #48 on: 15 May, 2024, 11:20:25 pm »
Yes. They are called tubeless. ;)

Hmm, not always reliable

I've had 2 non sealing punctures, both slashes
“Procrastination is the thief of time, collar him.” –Charles Dickens

Re: Tyre width
« Reply #49 on: 16 May, 2024, 08:31:02 pm »
Dawes Galaxy 32mm marathon or vitoria Randonneur tyres - flippin heavy and slow.
LeMond Zurich 851, 21 or 23 hp or Tubs - light and flippin fast.
Audax bike - somewhere in between.

As previously said. You need to consider the history to fully understand where we were 20 years ago. Back in the day (up until the 80s say) the options for road bikes were heavy 27" wheels and low pressure tyres 60psi max or light weight continental 700 'sprint' wheels with sew-up tubular tyres which could take much higher pressures. Hence the old photos of cyclists riding to races with their best sprint wheels strapped to the handlebars. This explains the prevailing wide - slow, narrow - fast philosophy.