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I'm looking at riding again. I took a two year break after I crashed going down a hill when a tree branch was down and I went over my handlebars.

I've always assumed that thinner tires were better for riding but I was watching this video from Global Cyclist Network. In the video the rider makes a strong argument for wider tires.

What I'm wondering is there any literature or empirical studies that are public that show these results? I found some small things that corroborated this but I was sure this would be the right place to ask.

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    What kind of riding you are referring to? Is it MTB XC, MTB DH, trail, road racing, gravel racing etc.? – Grigory Rechistov Sep 24 '18 at 6:36
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    Getting back into riding after a problem can be hard - both mentally and physically. Not dupes, but worth checking bicycles.stackexchange.com/questions/42383 and bicycles.stackexchange.com/questions/52340 and links therein. – Criggie Sep 24 '18 at 9:07
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    I don't understand why this gets flagged as opinion based when OP is specifically asking for published hard evidence. – Argenti Apparatus Sep 24 '18 at 12:12
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    Honestly, I'm not sure that tyre choice is going to make any difference to a collision with a tree branch that's big enough to send you over the bars. – David Richerby Sep 24 '18 at 12:24
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    There is sadly very little published evidence. Schwalbe used to have a nice couple of pages (in a pdf I think) of the research they did into MTB tyres at low pressure where they found on even the most mild off road surface wider and lower pressure was faster, but I cant find it any more. They do still have a little generic information about contact patch etc on the website. It would be nice if all tyres had to be submitted to an independant body for testing and graded accordingly (similar to how wet performance, noise and economy are graded for car tyres). – Andy P Sep 24 '18 at 15:08
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Depends what you mean by 'better', and under what circumstances. The major tire considerations are, in no particular order:

  • Drag or resistance
  • Comfort
  • Grip
  • Durability / puncture resistance
  • Mass
  • Aerodynamics

What constitutes a 'better' tire for you depends on your preferences and what kind of riding you want to do.

The hypothesis that GCN puts forward in a few of their videos is that narrower tire width and higher pressures do have lower rolling resistance on a smooth surface, but wider, lower pressure tires actually offer less overall drag over irregular or bumpy surfaces because they have less suspension losses.

The idea is that because wider tires don't necessarily have more drag you can run wider tires and get better grip and comfort without a penalty.

GCN did some relatively well controlled experiments on cobbled surfaces. Here is a video that talks about what they did and the results they got:

Some more experiments on bumpy surfaces: https://janheine.wordpress.com/2016/06/14/suspension-losses-confirmed/

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    GCN's head office is near me, and I can recognise the roads in some of their videos. Many of the quiet ones (good for filming and putting bikes through their paces) are far from perfect even assuming you avoid the actual potholes. The contrast between those and the roads that had been made good enough for a TdF mountain stage 11 months previously is marked enough that I would trust people riding ordinary roads over conclusions from major pro racing – Chris H Sep 24 '18 at 14:13
  • @ChrisH agreed - 'ordinary roads' in the UK are really draggy. A couple of years ago I turned up to the local race pace group ride on a gravel bike with 700x38's as my race bike was in the shop. Expected myself to get dropped pretty quickly (as did everyone else), but in the end, I found it was only slightly slower, and on some rougher sections of road was actually easier than on my race bike. In comparison, when riding on freshly surfaced roads in france, it feels like a 2% downhill when on the flat, and in this case i've no doubt skinny tires at high pressure would be considerably faster. – Andy P Sep 24 '18 at 15:02
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    @AndyP there's a bloke in the Audax club who comes out on a gravel bike, with the same tyres as I've got on my MTB! He seems to have not trouble keeping up. I'm going from 35s to 32s on the tourer as I wear out the 35s but that's it as far as I'm concerned. I've tried commuting on 25s and it's not for me. – Chris H Sep 24 '18 at 15:04
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    @ChrisH just goes to show that its mostly the engine that counts at the end of the day. I was reminded of this a couple of weeks ago when climbing the Tre Cime in the dolomites. Some guy on a MTB with knobblies flew past up the climb. What appeared to be national champions bands caught my attention, and it turned out to be Kristian Hynek of the Topeak Ergon team. – Andy P Sep 24 '18 at 15:33
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In addition to the "bumpy road" effects that Argenti mentions, consider this: two identical tires, both at the same pressure and both equally loaded, except that one is fat and the other skinny. They'll both have the same size contact patch, but the fat tire will have a relatively circular contact patch, and the skinny tire will have a more ovalized patch; the skinny tire will also have more vertical deflection at the center of that patch. When the tire deflects, you get hysteresis losses, so less deflection is be better. This gives the advantage to the fat tire.

It turns out that you can't really make a fat tire with as lightweight a casing as a skinny tire, so if you have a fat tire with a light casing, you need to run it at lower pressures (or make it heavier, and get more hysteresis as a result). It turns out that the tradeoff is worth it--you still get lower hysteresis losses (also, happily, fat tires are naturally less susceptible to snakebite flats, so you can get away with those lower pressures).

This has been written about here and here.

  • The problem with the argument is that at same pressure the wider tire has harsher ride. This is because the angle between road and tire at the end of contact patch is shallower, so the same increase in contact force and contact patch area happen at lower vertical compression. – ojs Sep 24 '18 at 18:00
  • I am not familiar with this effect. Can you tell me more? – Adam Rice Sep 24 '18 at 19:26
  • I think I explained it as clearly as I can. Try drawing a picture of the cross section of tire under load and it should be obvious. – ojs Sep 24 '18 at 20:56
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It's actually a sliding scale between energy lost to massage the tire, and energy lost due to road conditions:

  • If you ride on smooth roads, a relatively thin tire will give you the least resistance because it requires the least massaging of rubber. I think, the optimum is at the wide end of racing tires, or at the slim end of all-round tires.

  • If you ride on bumpy cycle paths, the thin tires will bounce too much on the roots and potholes. A wider tire will reduce this bouncing, and thus give you the least resistance. This is squarely within the range of touring tires, as far as I can tell.

  • If you want to go off-road onto soft, sandy paths, you need to reduce your tire pressure even more / use even wider tires. Again, these wide tires will give you the least resistance because other tires will move too much sand, and thus loose energy. Here we are talking about wide mountain bike style tires.

In each case, there is a best tire width, and that best width varies wildly. So, take a good look at the types of roads that you want to ride on, and choose a tire width accordingly. Then pay attention to your riding:

  • If you find that the bumpy parts of your rides are slowing you down too much, you may go for a slightly wider tire the next time you swap tires.

  • If you find that even the strongest bumps you encounter are not slowing you down the least, you are likely wasting some energy due to the larger rolling resistance of your wide tire. Try a slightly thinner tire the next time you swap tires.

With this, you'll eventually find a tire width that's perfect for your rides.

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NO.

In terms of speed, wider tires are heavier, have more rolling and wind resistance, more rubber to dissipate energy, so thinner tires are better for speed until they are too thin to be sucked in ground too much.

In terms of safety, wider tires are less controllable, have more inertion, while thinner tires are more easily get stuck between obstacles.

So, the tire width is a matter of compromise, you need to find those which work best right for you, but with experience it may also change. And, also, different grounds require different tires, the harder is ground the thinnier tire will work the best, and vice versa.

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    This is only correct under certain circumstances. In short, when aerodynamic losses by wider tyres are relevant and/or when the surface is very smooth. For example, on the wooden track of a velodrome. Effective rolling resistance over roads may be higher for narrow tyres with a high pressure. The last statement follows Jan Heine's line of argument and may be controversial. However, there is at least enough to this argument to disqualify a general statement "narrow tyres are faster". – gschenk Sep 24 '18 at 8:23
  • Wider tyres at the same pressure as the thinner tyre are faster because the contact patch to the road has a smaller surface thus less friction losses. Information on this can be found on (tyre maker) Continental's website. – Carel Sep 24 '18 at 9:36
  • @Carel that qualifier "at the same pressure" is a bit of a cop out though. Not many tyres of say 32mm can take the same pressure as a typical 25mm runs. Those that can are tough and have higher rolling resistance. So to make the comparison requires running the 25mm tyres soft, or only holds for small differences. In other words conti are oversimplifying things. That's not to say their conclusion is wrong in general though. – Chris H Sep 24 '18 at 12:00
  • @ChrisH: Speaking of roadbike tyres sizes 21, 23, 25 and 28mm which have normally a maximum pressure of 8 Bar. 32mm is already in another league and not your typical racebike tyre. – Carel Sep 24 '18 at 13:53
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    @Carel that comment is the first time in this thread typical roadbike tyre sizes are mentioned. And it's a pretty arbitrary distinction anyway something like a Durnao goes up to 32mm anyway (max 6.5bar). The max pressure for a Pro One varies from 8.5bar at 23mm to 6.5bar at 28mm (which would be quite soft for 23mm, at least with me on the bike). Quoting the Schwalbe website because I'm familiar with it; I've good a fair sampling of the Marathon series in my garage. – Chris H Sep 24 '18 at 14:02

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