It’s a big assumption that even rough tarmac or splitted roads are similar to cobbles… From my experience that is not even close even the smoothest cobbles are way worse then really ba tarmac ( unless it gets so bad that the limiter starts to be the fear of killing the wheel on potholes…).
For fast road riding I probably would stay on the 30-32mm range… As you run into external romwodth limitations on even the widest aero rims. That said I probably wouldn’t want to change my 2.1. Thunder Burt’s for smaller tyres on my grizl.
Something missing on this test is the impact that requiring support for wider tires has.
They had to default to a frame with wide tyre clearance.
There could be interface effects where a wider tyre works better with the frame in terms of attachment
A frame with wider tyre clearance will naturally have a larger frontal area
Appreciate this is impossible to test, but if you could scale a frame with the tyre size, the differences in aerodynamics would almost certainly be greater, even if it is difficult to know by how much.
No one mentions rolling weight, wider tyres are heavier so I go as light and narrow as is comfortable and durable and has best rolling carcase. I ride 30mm road, 40-50 gravel depending on whether smooth or rough gravel, 2.4 MTB, all on compatible light wheels. Maybe I’ll combine a couple bikes into a 40mm all road but that means less bikes so I’m not sure about that
FWIW: I like low tire pressure so with any tires from ranging from 23mm road to 2.5" mtb, I start at some reasonable pressure (say 95 psi for 23mm, 35psi for 35mm, or 25 psi for 2.4-2.5") and go lower in increments until I encounter something I don’t like, like cornering squirm or rim strikes, then go back a little higher. Pressure wise, I only consider ride, handling, and traction, not rolling resistance. It can vary depending on the riding and surface conditions.
This article seems like a valiant effort of data noise collection with a click bait headline.
This chart shows that 30mm tires on the hunt rims are the fastest. 7, 2.4, 5.2, 5.3 is all within their margin of error.
The rolling resistance watts column makes no sense. 6.2, 1, 3, .9. If wider tires were incrementally faster because of rolling resistance there would be a progression lower but since the 32mm was slower than the 30mm, I’m guessing that their data is just noise. They are all essentially similar at that level.
Their fastest combo is the 32mm wide inner rim Zipp gravel rim and a 32mm tire which is an unsafe combo. Since the Zipp rim is 40mm wide, the 35mm tires would have still been aero optimized and should have been the fastest if wider is faster.
The king of the road, IMO, is still a 35mm wide front rim (like a Roval) and a 28-32mm tire. Rolling resistance watts is less than the margin of error between 28 and 32mm so pick whatever tire you like.
Not a roadie here, just a retired veteran courier who played in traffic for a quarter of a century and loved getting lost in the forest on weekends. A famous YouTuber from the land of mandella was the first person I hired.
Have been running 38c tubeless schwalbe marathon almotions on the rear of my cargo bike for almost a decade and did it on a fleet of cargo bikes when I still owned my transport company, ran them for about 6 years full time without a single flat and haven’t had a single flat since on either my cargo bike or my surly ogre which i wish was a bridge club (that’d be perfect for 700 by 40’cs)
A bit surprised not many people in the comments have mentioned tubeless technology is vastly superior in 40c tyres when compared to traditional, thin road bike tyres. I believe that’s where the advantage of wider tyres and weight savings of not running tubes comes into their own.
It’s almost the same principals for casual mountain bikers. Vast majority of casual riders would be better off with 27.5+ rear wheels, 29+ front wheels, 120mm of front travel and a 10 speed 11-42 cassette with a 28tooth front chainring. That’s not what the pros or the bike industry execs want.
I weight 63kg and I’m running 25psi front 26psi rear on 40mm hutchinson touaregs (23mm internal wheelset). If I increase the pressure it’s too uncomfortable.
On a full suspension with 2.4 I usually never go lower than 15-16psi otherwise it gets too squirmy and unpredictable.
I no longer ride the old rim road bike on the road, It’s permanently attached to the Zwift hub. I think the future of road bikes is 40mm and lower tire pressures. The other day I was descending in the rain and I couldn’t imagine myself doing the same on 25mm
I think the CN headline is clearly clickbait; the conclusion seems to be that 40mm tires are faster (a lot faster) on cobbles, which I totally believe, but who’s riding mainly cobbles?
Our roads (Seattle area) are generally in pretty terrible shape, and I’m in for wider tires, but 40mm feels like too far unless you’re riding a lot of legit gravel along with your asphalt.
But, I’ve been running GP5000s in the 32 and 35mm sizes on 3T Discus rims (29mm ID with aerodynamics to match) and those have been great setups. Reasonable aerodynamics, smooth and fast, good grip even in the wet.
Yep. Too much psi too much deflection, too little squirmy.
2.5’s are perfect for my riding: dirt trails by the river that runs through my city & of course all the regular trappings of running busy urban streets, sidewalks, driveway aprons, & jumping curbs.
Yes. Even Paris-Roubaix is 200km of smooth roads and 50km of cobbles. The Pros won’t be riding 40mm tires as they need a balance.
The worst part of this study is that it looks like just noise. It’s the same with the NorCal cycling ‘wider is better’ videos - a handful of seconds or watts either way is just not super meaningful.
BRR showed that when you optimize air pressure in different sized tires, the rolling resistance equalizes.
The fastest tire is really a wide tire pumped up hard but nobody wants to ride that. Maybe someone like Ganna will win some races some day on a 35-40mm wide rim with a 32mm tire pumped up to 100psi?
The title of the article is click bait and it turns out that they didn’t find any huge differences between 26mm and 40mm for road riding. 26mm tires were the fastest. Here is the synopsis of the whole article:
Interestingly, on the smooth tarmac surface, the differences are negligible. But as you switch to a rougher surface, wider tyres make a huge difference. On the cobbles, the difference between the 26c and the 40c tyre on the Hunt rim is 29.8 watts at the slower speed, and 65.7 watts at the higher speed.
Now, how many of us ride on Cobbles? Even in pro bike races with cobbles, the cobble sections are some smaller percentage of the total bike race.
Thus no need to buy new wider wheels to accommodate wider tires for roadies. For chunky gravel, probably the wider the better. For smoother gravel, no need to buy new equipment.
Isnt the clickbait correct that we would all be better off on 40c tires. On smooth tarmac you are in the range of measuement error and if the tarmac gets bumpy then you get a massive savings. Given that most of us are riding in that 20mph range it seems like a no brainer that we should all be wider than the pros by quite a lot.
Im also questioning the data but if the data is true then I think the clickbait is correct.
They only showed “massive savings” on cobbles. I’ve ridden on cobbles once in my life.
The 40mm is one of their slowest combo. The fastest is the 32mm tire on the 58mm deep / wide gravel rim. To me that makes the case for rims like the 35mm wide Roval + an aero optimized tire (28 to 32mm).
They also didn’t take into account weight. 40mm tires would be slower up hills with the extra weight and extra sealant.
Mostly when I look at their numbers I see noise. Something is wrong with the 28c tire as it’s one of the slowest for some reason. Logically, it should be between the 26 and the 30. The rolling resistance progression on the Zipp 32 to 40c makes no sense. And that makes me think their data is a lot of noise. They can’t measure 2-3-5 watts accurately - maybe not even 10 watts.
Hmmm, I’d still take the article with more than a grain of salt. E. g. they used a rim with a 17 mm internal width for all tires. That’s very, very narrow by today’s standard. I don’t think many people will ride a 32+ mm on a rim that narrow.
For comparison, my rims have an internal width of 25 mm. According to Zipp’s tire pressure calculator, the difference in recommended pressures is around 10 psi.
That is in addition to the issue of getting good rolling resistance measurements for bad road surfaces. I would still think that in many cases you should try going wider and test it yourself.
That’s a very good point: we often link to rolling resistance test data and the differences for the best tires are typically very small, sometimes fractions of a Watt. How many digits are actually significant?
