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Myths in cycling: wider tires are slower

• louthy 5y ago
  If that were the case, surely Tour de France riders would use wider tyres to gain more grip going around corners, especially in time-trials or stages with sprint finishes. Doesn’t a greater surface area touching the floor means more frictional effects when pushing against the road?
  • bretthopper 5y ago
    The one caveat this article doesn't mention is worse handling but they replied in the comments about it. And handling matters way more at higher speeds, plus they commented the extra weight matters more for steep climbs too.
    • Cockbrand 5y ago
      This, and a wider tire also has a larger front surface, resulting in more aerodynamic resistance. As every watt counts in the pro peloton, this is an important factor. For us amateur riders, probably not so much.
    • loeg 5y ago
      I was a little surprised: the weight difference isn't huge. It is about +27% between Conti 5k 25mm and 32mm, or 60 grams per tire. Aerodynamics are the only real reason, I think.
  • mantas 5y ago
    They're already using wider tyres than a decade ago.
    • scoofy 5y ago
      Yes. Much, much wider. I nearly passed by this comments section because i assumed everyone already knew this was true.
      • at-fates-hands 5y ago
        I think you're exaggerating a bit. From 2018: https://www.businessinsider.com/tour-de-france-wider-tires-lower-pressure-faster-2018-7 https://www.businessinsider.com/tour-de-france-wider-tires-l... "It depends on the road surface, but 10 years ago the standard was 23mm tires at 8 or 8.5 bar, or 115, 120 psi," Brown said. "And now it's 25mm for regular road racing and 7 to 7.5 bar for front and rear, so a little less than 100 to 110 max on the bikes." 2mm and 10psi less is not that huge a difference.
        • mantas 5y ago
          It's pretty big when you take into account whole context. Stuck up "socks size is a rule" UCI, historical norms, technical limitations (25mm is a limit for caliper brakes), tire tech (wider tires used to be heavy).... My prediction is 27mm being the norm in next 5 years. Currently I'm riding a decade-old road bike. It was fancy at the time because it fit 25mm tires without issues. People would give me shit for "slow" tires on group rides. But 25mm tyres improved a lot in that time. Now I wish it could take 27mm :(
          • loeg 5y ago
            25mm is not a limit for caliper brakes? No idea why you claim that. One of my bikes has calipers and can fit 33mm tires. Also 28mm is extremely common; 27mm doesn't exist.
            • usrusr 5y ago
              There are definitely calipers that can't take a 28. And the mounting bolt position isn't a precise norm, there are frames that put the brake considerably closer to the rim than others. And not without reason, the effective length of the caliper arms has an obvious influence in brake leverage.
            • mantas 5y ago
              Classic road bike caliper breaks don't >25mm. 33mm would be cantilever CX brakes. Or a weird type of caliper.
  • kazinator 5y ago
    Regardless of whether it is the case or not, Tour de France riders would not use wider tires to gain more grip around corners because ... wider tires do not add more grip. You get a larger contact patch from a wider tire, but that patch has less pressure. Grip (static friction) is coefficient of friction, times weight. The coefficient of friction is a constant which depends on the materials. Rubber on road is no exception.
    • Retric 5y ago
      That’s the first order effects, however substances deform under pressure which is just one of many complexities involved. For car tires on dry pavement you get maximum grip from racing slicks. Unfortunately they need to swap in the rain.
      • kazinator 5y ago
        First order effects are the only effects which matter in cycling. This isn't aerospace. Racing slicks are a different material. In Formula 1 racing, you go through multiple tires in one race. In consumer driving, tires are expected to last 100,000 km or more. There is even the practice, in racing, of using chemicals to attack the rubber to soften it.
        • carl_dr 5y ago
          > In Formula 1 racing, you go through multiple tires in one race. They could easily make a tyre which lasts the length of a race, but they mandate pit stops and two different tyre compounds to add interest - teams can use the mandatory pit stop to “undercut” or “overcut” competitors. In fact, IIRC, for the 2005 season, changing tyres mid race for anything other than safety reasons was banned. > In consumer driving, tires are expected to last 100,000 km or more. This is much closer to 25,000-50,000km, and peaking at 70,000km. Source: https://www.pirelli.com/global/en-ww/road/how-many-kilometres-can-a-tyre-cover https://www.pirelli.com/global/en-ww/road/how-many-kilometre...
        • Retric 5y ago
          Using a different material is in effect irrelevant, they still get maximum grip from maximizing contact area because of how rough roads are. Ultra narrow tries need higher internal pressures, which limits how much the deform and thus reduces grip. Also, F1 cars are going up to 246 mph and doing heavy acceleration and breaking throughout the races, which seriously heats up the tires. Normal road tires would actually die sooner under those conditions. Just read up on who long tires last when people are doing street racing, burnouts, etc.
  • deleted 5y ago
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  • carl_dr 5y ago
    From TFA: “ We tested our tires on smooth pavement at 29.5 km/h (18.3 mph), and found no speed difference between narrow and wide tires.” A professional peloton rides at 28-30mph on the flat and significantly faster towards the end of a flat stage - I bet at higher speeds, for professionals where every percent matters, it does make a difference. Certainly for my level (and I have ridden for an hour at 18mph average) it doesn’t.
    • bmj 5y ago
      It is worth noting that tires used by the pros have used slightly wide tyres over the years, and for events like Paris-Roubaix and Flanders, they absolutely use wider rubber on frames with more clearance.
    • medstrom 5y ago
      "We tested our tires at the same speeds and found no speed difference". You don't say?
  • periheli0n 5y ago
    The problem is that wide tyres tend to eat lots of momentum in corners. When going mainly straight and/or on uneven ground, use wide tyres. When cornering a lot, use narrow tyres.
    • outside1234 5y ago
      Also, they have higher raw weight, so thinner is better uphill.
      • mijamo 5y ago
        This is actually not really true. Competition bikes have a minimum weight nowadays, and technology is that advanced that it wouldn't be a problem to add some weight here or there because the bike would stay the same weight in total as they have so much margin else to keep in track with the minimum weight. This is why most teams have switched to disk brakes btw, and that they can have all the electronics onboard with power meter, bike computer etc.
        • localhost 5y ago
          But there's rolling "sprung" vs. static "unsprung" weight (the examples you listed). You care a lot more about rolling weight as that affects the acceleration characteristics of the wheel - that's really important at the limits.
          • oriolid 5y ago
            If you bother to do the math, but simplify things so that all the mass of wheels is at the contact patch, you'll end up that rotating mass has twice the kinetic energy and takes 2x effort to accelerate and decelerate. Now if you check how large fraction of the mass of rider and bike the wheels are and how fast bikes accelerate, it's kind of insignificant.
        • usrusr 5y ago
          Technology was advanced to routinely end up with bikes beneath the minimum, but those days are over. With wider tires, disc brakes, excessive focus on aerodynamics and even wider gear ranges they are usually racing considerably above the limit. These days you'll find bikes in the range of 5000 euros advertised that are considerably heavier than what you would have got for 1500 ten years ago.
  • dredmorbius 5y ago
    Static friction being constant regardless of contact surface presumes a uniform surface consistency (uniform frictional coefficient). Large (an knobby) tyres are a statistical bet that there will be sufficient friction somewhere on the contact patch. When riding over nonuniform surfaces (dust, loose pebbles, twigs, mud, leaves, and embedded rock), that's a gamble the large and contoured tyre is far more likely to win. On a velodrome deck, not so much, and cross-sectional area, thermal losses from compressive deformation, angular momentum, etc., favour thinner tyres and higher inflation pressures.
    • bernulli 5y ago
      Is the static friction what is going on with wheels? Why do race cars (dragster, F1, etc) have wide, smooth (un-knobby) tires if it's so disadvantageous (no gain, but higher weight and moment of inertia)?
      • dredmorbius 5y ago
        For your standard street-car tyres ... mostly, modulo variations in surface, rain, snow, mud, etc. On reasonably fresh dry clean tarmac though, yes. For racing tyres ... you're getting into a differet set of circumstances and uncomfortably far from my knowledge and experience, though my understanding is that the rubbers are specifically engineered to be sticky, more so at high temperatures (hence why drag racers spin out, it warms the tyres). That's no longer the domain of static friction. There's also the matter of thermal management, where tyres at high speeds generate a lot of heat. How much size affects and/or is determined by this, I don't know. I am aware that street-tyre speed ratings are based on thermal properties, however. Knobby tyres are most effective on non-uniform surfaces: dirt/rock and mod most notably.
      • adrianN 5y ago
        It is my understanding that race cars have wide tyres to shed more heat. Tyres melting is a problem at F1 speeds.
      • saberdancer 5y ago
        Softer tires give more grip but are less resistant to shearing forces. Having a wider tire helps with that.
  • taude 5y ago
    Here's a pretty interesting article discussing Le Tour slowly getting wider and wider tires, compared to a decade ago [1]. Granted their use case is going to be at a very different scale than most rec/serious non-pro riders. But I know that most all my friends and I ride 28s on our road bikes these days compared to 23s a long time ago. More comfort and more forgiving. My current road bike maxes out at 28, but I'd probably go a little wider if I could due to the nature of the roads around here (lots of potholes, chunks, crappy shoulders, etc...) [1] https://www.businessinsider.com/tour-de-france-wider-tires-lower-pressure-faster-2018-7 https://www.businessinsider.com/tour-de-france-wider-tires-l...
    • bombcar 5y ago
      You also have the theoretical perfect tire vs the actual best for the rider - the more comfortable tire may be better overall as it allows the rider to perform better and for longer.
  • gameswithgo 5y ago
    Tour De France riders do use wider tires than they used to these days. At some point the width starts imparting aerodynamic drag penalties that are worse than the handling gains.
  • CalChris 5y ago
    You can't really rely on the Tour de France peloton for guidance. They're pretty conservative and, to a degree, ruled by fashion and sponsors.
    • carl_dr 5y ago
      I guarantee the masters of marginal gains, Sky (now Ineos Grenadiers), will have spent some resources on looking at which tyres are actually faster for them, regardless of fashion or sponsors. I think it’s safe to say that whatever they ride on are the fastest options - and every other team would follow - or that within a certain set of parameters, it doesn’t matter. I just tried to search to see if Ineos run different tyres on different race and stages, and found nothing conclusive.
      • dropofwill 5y ago
        According to eurosport commentary they do change wheels and tires based on the race. That said they use rim brakes so probably never go over 28m tires.
    • deleted 5y ago
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    • idoubtit 5y ago
      Cycling teams spend tens of millions each year, with Ineos going over € 50m some time ago. Are they conservative? They benchmark their material in wind tunnels. Sometimes they bend the rules with high-tech material[^1]. There's no way a team competing in Tour de France would choose fashion over performance. [^1]: https://www.theguardian.com/sport/blog/2017/jul/03/vortex-suits-team-sky-tour-de-france-marginal-gain https://www.theguardian.com/sport/blog/2017/jul/03/vortex-su...
      • usrusr 5y ago
        And quite a bit of the money they spend comes from companies trying to sell gear to hobbyists. It's a rather wild mix between ride what makes you fast and ride to pretend that it makes you fast.
  • dahart 5y ago
    > Doesn’t a greater surface area touching the floor means more frictional effects when pushing against the road? Good question because at first I thought it might be negligible due to the tire normally being in a state of static friction relative to the road. But some quick searches showed me that rolling resistance is related to how large the contact point is, like you suggest, along with a variety of other factors. https://en.wikipedia.org/wiki/Rolling_resistance https://en.wikipedia.org/wiki/Rolling_resistance I don’t know how reliable this is, but googling brought me to this site which compares bicycle tire brands according to rolling resistance on their test machine. Apparently, some 25s have all the 23s beat. If true, the variability range for bicycle tires is a lot wider than I expected. https://www.bicyclerollingresistance.com/ https://www.bicyclerollingresistance.com/
    • Cockbrand 5y ago
      I've bought a few tire models after researching at bicyclerollingresistance.com, and while I certainly don't have the means to do proper scientific research, I feel like I did buy the right stuff.
      • jeffbee 5y ago
        Same. I don't have any rational basis for it, but I've been happy with my tires. I think the best thing I learned from that site is even slightly larger sizes have a much bigger effect on puncture resistance than better construction.
    • nchie 5y ago
      I love brr.com and have used them a lot, but in the context of this thread, it's important to consider that the surface they test the tires against do not have the kind of imperfections you see on the road. This means lower pressure will always perform worse in their tests, which goes against the more recent consensus in that each road has an optimal pressure depending on its roughness.
  • davisoneee 5y ago
    One thing every person has missed so far is that often the TDF riders are on rather narrow bikes with very little clearance. This helps give an aerodynamic profile. Even at a few watts, this is considered worth it. You would likely have to do a lot of research to go with bigger wheels, as that would been wider fork, and thus throw off aerodynamics. A bit daft, in my opinion, given that it's mainly the domestiques who are in the wind and the ones behind, and in the peloton, can be putting out significantly less energy. May even be better for recovery having a bit more comfort on the bike through wider tyres with a bit lower pressure.
  • uoaei 5y ago
    Path Less Pedalled recently had a great discussion on this with Josh Poertner, the owner and president of Silca, the tire pump company: https://www.pathlesspedaled.com/2020/01/09/your-tires-are-lying-to-you/ https://www.pathlesspedaled.com/2020/01/09/your-tires-are-ly...
  • adnmcq999 5y ago
    Yeah I haven’t read the article yet but OP is making flat-earth level claims Even in Paris Roubaix (where there are cobbled sections) they ride 28s
  • deleted 5y ago
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  • AtlasBarfed 5y ago
    Tour riders are EXTREMELY conservative, well they were back when Lemond pushed clipless pedals, more helmets, and aerobars. The nameless scapegoat who was totally the only person using EPO pushed more thorough full-system wind tunnel testing/aerodynamics and a lot more scientific testing, and even (gasp) clincher tires. Euro riders for a long time worshipped Eddy Merckx (who was totally clean and never doped) and thought you basically only needed an italian bike and nothing else and were culturally averse to change. Also, keep in mind the Tour riders are basically showcasing industry products, and those products aren't really that diverse in their sourcing, especially with globalization. They all run on whatever they are getting for free or at a vast discount from the two or three providers in each equipment category.
  • lamby 5y ago
    > "If that were the case, surely Tour de France riders would..." Apologies for appearing to pick you out here, but your comment is representative of a number of eminently "logical" comments made here (as well as many analagous comments on HN in general). So, modern professional cycling is a sport with a 100+ year history, and in 2021 represents a bizarre fusion of the sports entertainment industry, the romantisation/revival of the past, celebrity culture, global cycling manufacturers, the mid-life crises of Wonka-esque team owners, the aestheticisation/fetishisation of the working class, the 'Olympics industry', lurking labour disputes, the fast fashion sector, the ad-hoc application of modern sports psychology, a looming confrontation with its historical emphasis on (mostly horrifically underpaid) white males, neoliberal economics, petty and bountiful financial corruption, widespread pharmaceutical corruption, and the influence of petrochemical money from several ex-Soviet states... All mostly filtered through the celluloid lens of France and Italy, two European nations that have an extremely complicated relationship towards their own history which comes out as a muted pageant of lukewarm national pseudopopulism that is not only is confused within its own borders, but is more-or-less unintelligible to those in the Anglosphere. To imply in any way that a kind of efficient market analysis can apply to decisions made within this sport (that has, if I remember correctly, strict rules about sock length), suggests an insufficient engagement with the background.
• soperj 5y ago
  Another one is that clip in pedals make you faster.
  • aeharding 5y ago
    Do you have a source? Anecdotally I've found clipless to make my power transfer more efficient. Some quick googling shows this seems to be true: "Mean power output was higher using clipless pedals ( = 617 watts, SD = 112) than toe-strap ( = 572 watts, SD = 77), and flat ( = 566 watts, SD = 83)." [1] [1] https://scholars.fhsu.edu/cgi/viewcontent.cgi?article=1118&context=theses https://scholars.fhsu.edu/cgi/viewcontent.cgi?article=1118&c...
    • at-fates-hands 5y ago
      I was a life long flat pedal rider. Started working at a bike shop during college and one of the first things roadies told me was they are indeed much more efficient because you can push AND pull on your pedals - generating a lot more power and making the ability to sustain that power a lot easier.
      • carl_dr 5y ago
        I think this is a myth - you don’t pull on your pedals to make you more efficient, I think it’s the fact you are not continuously having to adjust your feet as you would on flat pedals. See https://www.bikeradar.com/advice/fitness-and-training/stop-pulling-up-on-your-pedals/ https://www.bikeradar.com/advice/fitness-and-training/stop-p... for instance.
        • fsckboy 5y ago
          a better way to say what you might be saying is, "without locking your feet to the pedal, you expend significant energy with lateral muscle movements to keep your feet on the pedals"
        • PaulDavisThe1st 5y ago
          One issue I have with that bikeradar article is this quote: >Undertake your next few leg-speed intervals at the same cadence (such as 105rpm), but aim to remain more firmly planted in the saddle, with your pelvis acting as a foundation for your legs. This will allow you to maintain chain tension through the entire stroke, eliminating the ‘thud’ through the top and bottom of the stroke (the ‘dead zones’) as your chain loses contact with the freehub Anyone who experiences what the author describes as "the thud" is pedalling so badly that almost anything they do to improve their stroke is going to be huge win. I'm not sure his advice is on point for people who already have reasonable pedalling technique.
• carl_dr 5y ago
  I’ve ridden 25mm to 32mm tyres on the same bike, in the same season, and my (absolutely amateur, I’m 250lb and did 125 miles at 16mph) experience is that 32mm tyres are no slower, but are significantly more comfortable, and allow me to ride significantly longer with less fatigue. Does anyone else have any other data points?
  • haswell 5y ago
    I've spent a lot of time with 28mm tires, but I'm absolutely in love with my 38mm GravelKing slicks. I don't really notice much speed difference (if any), and the comfort level makes up for it if there is. I ride for fitness, so I'm happy. More details in my other comment (I actually ride a gravel bike so I have the extra clearance for big fat tires if I need).
    • kazinator 5y ago
      The comfort level you feel is also a form of efficiency that makes you faster. Vibration absorbs energy and saps your momentum.
  • twoWhlsGud 5y ago
    This is all anecdotal, but a couple of decades ago I was riding road bikes with standard 622 rims shod with 23 mm tires. In the 2000s I shifted to riding road bikes with 584 rims and 42mm tires because they were frankly just more fun for me (lower pressure = greater comfort and better suspension meant better handling on our rough Northwest roads). The outer diameter was about the same, so I didn’t have to do something weird with the geometry of the bikes. When Jan came out with 55mm super-supple tires on 559 rims (again that would keep the outer diameter the same) I thought what the heck and got Seven Cycles to build me a custom around the new tires. Now that road bikes run disk brakes, you can run multiple rim size on the same frame so I figured I could always go back to 584/42mm if I didn’t like the crazy wide tires. (I was worried enough that I actually got somebody to build me a new set of 584 rims for the new frame.) I’ve had that bike for about 3 years now and have ridden several thousand miles on it. Only a few tens of those miles have been on the fancy 584 rims with the (equally nice) 42mm tires – the 55mm tires are even more fun than the 42's were for me. If you ride on mixed surfaces, the extra suspension you get from running low pressures (I run around 26 PSI front/32 back) makes a big difference (or at least it does for me) - both in handling and comfort. Downsides are increased weight (the 55mm tires weigh about 420 g a piece which is impressively light given the amount of material, but still a lot heavier than those old 622/23 mm tires back in the day) and the increased maintenance of running them tubeless (though of course you can run them with tubes-though given that I haven’t had a flat in 3 years and I’m riding on Seattle streets, I’ll put up with having to monitor the sealant levels every month or so).
• periheli0n 5y ago
  Years ago I switched from 1" tyres to 2.5" inch ones for my commuter bike and I can confirm that they are not slow at all... as long as you ride in a straight line! As soon as you turn, they suck up all momentum. The fact that they provide decent straight-line rolling even at 2bar pressure is nice though, especially in a city where cobblestone paving is common. Fat tyres provide some suspension, and a ton of grip. Still, narrow tyres are the choice for fast riding if you need a bit of agility.
  • kazinator 5y ago
    I completely believe you, but the issue is likely not width per se. Might it be that your tires have a smooth profile down the middle for going in a straight line, but edges that have a more aggressive tread pattern, which engages the road surface when you tilt into a turn? There are true fat road slicks that have the same smooth profile all over. I think, tire pressure is also a factor in turning because of the way the tire deforms on the rim. If you have the pressure way down (which you can easily get away with in 2.5 inches), that could be a factor.
• draw_down 5y ago
  Seems reasonable that more tire contact = more friction.
• haswell 5y ago
  This is one of the reasons I love the emergence of the "Gravel" category of bikes. They look and have geometry similar to a road bike, but they have enough clearance for nice fat gravel tires. I ride in Chicago (shitty roads, potholes & construction are everywhere), and love that I can put nice 38mm+ GravelKing Slick tires on the bike, and still have no problem keeping up with most road bikes. I've gotten funny looks from folks who're unfamiliar with the concept, but it's such a great setup. Comfy/soft ride too. Edit: Cannondale Topstone if anyone is curious.
  • thisisnico 5y ago
    My bike is the best for the city.. got a Specialized Tri-Cross with 32mm tires.. can do everything and handle our horrible roads.
  • krono 5y ago
    Yeah, my roady friends are jealous because I get to use my gravelbike off-road, and my mountainbike friends are jealous at me for being able to keep up with roadies. And all that for the price of one bike and an extra set of wheels with slicks! Canyon Grail here, yes the one with the weird cockpit :)
    • photojosh 5y ago
      How off-road do you go? I have a gravel bike too, but I much prefer the MTB for rocky descents.
      • whakim 5y ago
        I also own a Canyon Grail (the alloy one, so no weird handlebar) and it's pretty capable for fire roads and some singletrack. When it gets really rocky and rooty though I find myself having less fun simply because the riding experience becomes so jarring and rattly. It's also way more fun to climb on (as in you actually enjoy the climbs as opposed to just doing them to get to the downhills) compared to a mountain bike. Where I live I have to ride ~7 miles each way to get to the trails so it makes a lot of sense as my one off-road bike.
• analog31 5y ago
  I suffered with this myth for decades. Now, it didn't affect me too much because the narrower tires that I got, also took a lot higher pressure, and I usually inflated them to the max. And as a result of only caring about skinny tires, I neglected tire clearance on my frames. Then a few years ago I got a bike that could take wider tires, and was good enough quality to really try out for real. Today I'm one more anecdotal data point in support of wider tires. Now, I don't necessarily opt for the lowest possible rolling resistance. Instead, lowering the pressure allows me to ride in greater comfort but without the tires feeling slow. And of course other things affect rolling resistance too, such as (from what I've read) the suppleness of the sidewalls and other aspects of tire construction. And I'm not prepared to spend $$$$ to find the holy grail of tires.
• CalChris 5y ago
  Narrow tires also require higher pressure with a less comfortable ride. Bigger riders, Clydesdales, require more pressure. These rock hard tire inflations are then more prone to snake bite flats. As the discussion section in the article points out, wider tires used to be common. I think we're rediscovering why.
  • kazinator 5y ago
    Snake bite flats are precisely from low pressure. The term comes from two punctures that come from the rim pinching the tire, which is due to inadequate pressure to absorb an impact. Rock hard tire inflations are prone to failure from the pressure itself.
    • CalChris 5y ago
      I short handed it a bit. My point was that this 'low pressure' for heavier riders is higher than it is for lighter riders. If you don't increase your tire pressure, the same pressure will cause more snake bites for a heavier rider than it would for a lighter rider.
• durkie 5y ago
  wider tires also let you run lower pressures, which puts you more in the comfort zone of being able to convert to tubeless. not every rim/tire combination works with tubeless, but if you are able to pull it off, it's among my personal top 5 list of cycling innovations of the past 30 years.
  • wolverine876 5y ago
    I'm missing something: How do lower pressures lead to tubeless?
    • davisoneee 5y ago
      Narrow tyres tubeless is a no-go as the high-psi required to get the tyre seated and shaped can cause blowouts, especially if you get impact such as a pothole. Going for wider tyres means you naturally can go lower PSI, but if you drop PSI with tubes you risk pinch-flats ('snakebites'), where striking a hard edge causes both edges of the tyre to puncture (like X___X on the cross section, rather than \__x_/ of a normal puncture). If you go wide, you can then drop the pressure more as you don't have a tube to pinch. This gives you the great comfort, the pliability to absorb road imperfection (which improves speed), and less likelihood of puncture. As an approximate pressure guide: # weight in kg. front load probably 0.45 (45%). tyre width in mm weight_front = weight * front_wheel_load weight_rear = weight * (1 - front_wheel_load) psi_front = (338.14 * weight_front / tyre_width ** 1.5785) - 7.1685 psi_rear = (338.14 * weight_rear / tyre_width ** 1.5785) - 7.1685 This should ballpark you 15% tyre deflection under load, which was a guide from an old bike magazine on a balance of rolling resistance and comfort.
    • deleted 5y ago
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    • durkie 5y ago
      'davisoneee covered it pretty well, but mostly lower pressures mean it's less of a pressure differential that the sealant has to withstand. "Road tubeless" setups exist for narrower tires, but a lot of them have upper pressure limits around 80 psi / 5.4 bar. Running wider tires / lower pressures gives you a bit more margin of error.
• onethought 5y ago
  How is this a test if they didn’t measure energy expenditure? Using a human rider feels like a flaw here.
  • KeplerBoy 5y ago
    It's a flaw, but also a feature. If the enhanced comfort of a wider tire reduces the perceived extertion, even though the actual power needed increases, it's a net win in my view.
  • tomglynch 5y ago
    Their test using the rider's watts is energy expenditure
• kazinator 5y ago
  Narrower tires, necessarily inflated to a high pressure, are actually inefficient on a bumpy surface. A tire's job is to absorb surface defects in the road, and that is not only for comfort, but rolling efficiency. The extreme example of this occurs off-road. Off-road vehicles benefit from wider tires that are inflated to a lower pressure. If you have an off-road vehicle, it behooves you to take some of the air out of the tires when you go off-road. 25mm road bike tires basically require a polished velodrome; real roads consist of pitted, eroded and cracked asphalt. If your bike is vibrating from the crappy road, you're probably not going as fast as you could be. Letting some of the air out for a more efficient, smoother ride is risky, if the tires a narrow; you risk snakebite flats and damage to the rim. For commuting in run-down city with aging infrastructure, you want at at least 38 mm tires. 40 mm is a nice round number. You can vary the pressure for the kinds of roads you're riding on with a lot of margin, and can take it quite low for dirt roads. I've commuted around town with pressures as low as 45 psi in the back, 35 in the front, in 45 mm tires. I have story in relation to that. One time I was riding along NW Marine Drive in Vancouver, from UBC down to Spanish Banks. I came down from the hill and then along the flats there were some Spandex-clad road cyclists ahead of me. I pulled up to them and we were neck and neck. There was road work going on up ahead and the pavement had been scraped, leaving it horribly bumpy. I stood on the pedals and just cranked right through it, hardly slowing down. I saw in the mirror mounted on my eyeglasses that road bike guys dropped off as if a sniper had taken them out. What is the use of narrow tires? It's just fashion, like stiletto heels.
  • fsckboy 5y ago
    You're commenting on a article that says "we started to question many of the things we had accepted as ‘facts’... we’ll look at some of these myths. We’ll explain why we (and everybody else) used to believe them, and how things really work" But you aren't qualifying what you're saying: Are you telling us what everybody used to believe? Are you saying you see through what everybody says even without empirical testing? Are you agreeing or disagreeing with the test results presented in the article?
    • kazinator 5y ago
      > Are you telling us what everybody used to believe? No; pretty much everything in my comment is undisputed old hat, so it is kind of tangential. The main myth is not that any of that is false, but rather than thin tires more than compensate for these effects due to their reduced air drag and weight and so always end up being advantageous anyway. (And they almost certainly are on a polished indoor velodrome track, where the effect of surface imperfections is next to nonexistent.)
• TheAlchemist 5y ago
  Is the data available somewhere ? It doesn’t match my experience at all. I have a road bike and a gravel bike - same quality range (gravel slightly higher). At low speeds, that may be true - the difference is negligible. But at higher speeds / power outputs, the road bike beats the gravel hands down - by a significant margin (big enough to be felt, without a power meter)
  • brianwawok 5y ago
    Does your gravel bike have road slicks? Is your geometry the same, i.e. your reach and drop is the same?
    • TheAlchemist 5y ago
      No. Fair point indeed - the tires are not the only difference. I suspect they are one of the biggest though (based on subjective feeling - for what it’s worth).
      • reubenmorais 5y ago
        It's almost physically impossible for the tires to be a bigger difference than geometry (and thus your position), specially at faster speeds as you mentioned, because aerodynamics quickly dominate the overall resistance you're fighting to keep your speed.
  • derbOac 5y ago
    My impression from reading articles and technical reports about this is that there's a couple of things going on. First, I think the wider-tires-are-faster argument has to be appreciated in the context of the narrow-tires-are-faster argument that dominated for a long time. With the latter paradigm, you wanted your tires as narrow as possible, with some lower boundary constraint due to wheel and tire thinness limitations, maybe around 20-21mm. The former paradigm emerged in part in contrast to that, in that "wider" doesn't mean "infinitely wide" but rather "wider than what's typical for people striving for narrower tires". Some of the arguments about rolling surface area are maybe understood in that context -- the patch of tire in contact with the road maintains the same area as a minimal area under the narrow tire paradigm, and then it starts to become larger, at which point you start increasing friction theoretically with more tire surface area in contact. The other argument for wider tires is about impedance gains due to wider tires -- decreased vibrations basically. This is different than decreased or equal rolling resistance per se. However, there are eventual aero losses for wider tires, as well as weight increases (which then increase rolling resistance). Eventually these aero losses and weight increases overshadow any impedence gains, and the wider tires' costs exceed their benefits. This is the sort of thing about cycling that is frustrating to me. I love cycling, but so many mechanical factors get really oversimplified: costs aren't often realistically assessed against actual gains, and sometimes gains are very restricted in the circumstances under which they apply. Disc brakes, for example, are safer, but you see little discussion about whether the safety margin they afford actually would make any practical difference in scenarios in which accidents typically occur (e.g., where a car is coming from the side or a blindspot), and they're often heavier and less aero (so yes, they save your carbon wheels, but you almost have to have deep section carbon wheels to make up for their weight and aero costs to begin with). I'm not saying disc brakes are a bad thing, but I think in practice their gains are more complex than is often made out to be. In the same way, wider tires are probably more optimal than a lot of people thought in, say, 1985. But I think the pendulum has swung a bit too indiscriminately in the other direction at the moment. What's probably most accurate is to say you want the widest tire that affords some impedence gains given your typical riding surface, and not anything wider. Aero effects increase exponentially (?? polynomially?) with speed (that is, as your speed increases, aero effects become more of a factor in further speed increases), which would match your experience. As your speed increases, the wider tires become more and more of a burden, and require higher wattage to compensate for. All sports with any significant tool involved are full of misperceptions and myths, not supported by science. Cycling is full of them, but it's not the only athletic discipline like that.
• falcolas 5y ago
  So, I wouldn't expect them to be slower (except in the most extreme cases with aerodynamics), since you can make anything go fast with enough power. But along that line of thinking, I would expect larger tires to require more energy to keep at speed. A larger tire with a a larger contact patch implies a greater deformation of the tire, which in turn implying greater energy loss. Cars, using a measurement of gas mileage, have shown this. Smaller contact patches (a condition created with over-inflated tires) result in higher gas mileage, whereas larger contact patches (under-inflated tires) lower gas mileage. I didn't see this addressed directly, that I saw.
  • marwatk 5y ago
    Wouldn't the size of the contact patch be dictated entirely by tire pressure and not tire size? A 100lb person+bike and 100psi inflation means 1 sq inch of contact regardless of tire dimensions. They're circles on a plane, after all. In ideal conditions they'd only contact at a single point.
    • bri3d 5y ago
      No, because the tire has substantial structure and isn't a latex balloon, for lack of a simpler explanation. In the case of automotive tires, the carcass (structure) of the tire governs the contact patch much more than the inflation amount.
      • wiredfool 5y ago
        So, part of the point of the Rene Hearse tires is that they’re as supple as they can possibly make them. They are producing essentially the same best tire that they can in a huge range of sizes. (Well, at least until they started doing endurance casing and knobbies, so now it’s more like 4 of the best tires they can, aimed at slightly different target users/races)
    • efraim 5y ago
      Yes, with pneumatic tires the contact patch area is the load force divided by the pressure.
• crawdog 5y ago
  Makes my day to see this company on HN. Their Barlow Pass tires in tubeless setup have been an excellent addition to my commute bike. Supple, great handling. There's an efficiency lost on a gravel setup vs road bike, but that's mostly the geometry than the tire.
• wolverine876 5y ago
  > in theory, wider tires are faster due to their shorter contact patch, which deforms less as they roll What is meant by "contact patch"? If it means 'portion of tire in contact with the ground': Assuming the tires are the same circumference, I'd expect the front-to-back dimension of the contact area to be the same, and being a wider tire, the side-to-side contact dimension to be larger, creating a larger contact area. And given equal force on the tires, wouldn't the same force deform a smaller contact area more, not less? What am I misunderstanding? > Laboratory tests on steel drums eliminate the rider and thus the suspension losses. If you look at hysteretic losses alone, narrow tires run at higher pressures and thus flex less, meaning they absorb less energy. > We tested on real roads, with a rider on the bike, and found that the increased vibrations of the narrower tires caused energy losses that canceled out the gains from the reduced flex. These suspension losses are mostly absorbed in the rider’s body. How do hysteretic losses apply here? And, why does the increased vibration cause energy losses (which I take to mean reduced efficiency of energy used for movement)? If the energy is absorbed by the tire or is transferred via other bicycle components to the rider, what's the difference in energy loss/efficiency?
  • davisoneee 5y ago
    If you're going OVER imperfections (i.e. high pressure tyres), you lose some energy going 'up'. If you go THROUGH imperfections (lower pressure) you don't lose so much energy going 'up' as the tyre absorbs rather than bounces you.
    • wolverine876 5y ago
      Thank you, but maybe I'm being dense: Tire hits bump, causing energy B to impact tire. The whole bike and rider go 'up' or just the tire goes 'up'. How is the former causing more energy loss? The amount of energy is B either way. I can see how one is more comfortable, because the tire takes the hit and not me, but I don't grasp the difference in energy.
      • davisoneee 5y ago
        When the pressure is lower, less energy is deflected upwards. The tyre flexes over the hit. _ \________/ \___/x\___/ versus x Less energy is transferred to the 'up' meaning the energy is still going forward. You still have upward motion, but that's less energy taken away from forward motion.
• wolverine876 5y ago
  Can anyone recommend serious science and engineering sources on bicycles? I've looked hard and only found a couple: * Bicycling Science by David Gordon Wilson: Book by MIT mechanical engineering professor, going back four editions to the 1970s. https://mitpress.mit.edu/books/bicycling-science-fourth-edition https://mitpress.mit.edu/books/bicycling-science-fourth-edit... * "Bicycle Technology" by SS Wilson in Scientific American (Mar 1973): Great starting point on the technology and it's development. PDF: http://veterancycleclublibrary.org.uk/ncl/pics/Bicycle%20Technology%20Scientific%20American%20March%201973%20(V-CC%20Library).pdf http://veterancycleclublibrary.org.uk/ncl/pics/Bicycle%20Tec... Here's a few more I haven't yet pursued: * Journal of Science and Cycling: Open access online journal https://www.jsc-journal.com/ https://www.jsc-journal.com/ * International Human Powered Vehicle Association (IHPVA) and World Human Powered Vehicle Association (WHPVA): Apparently one association that split acrimoniously in the 2000s. I haven't pursued this. * Cycle Engineers Institute (CEI) (UK) * European Cyclists Federation (ECF) I'd love to find other publications, and a community and forum. When I ask around at bike shops, most people refer me to Park Tools, which isn't what I'm after.
  • sam 5y ago
    If you're interested in wheels, check out The Bicycle Wheel by Jobst Brandt. If you're building wheels it's a must have.
  • adolph 5y ago
    https://sheldonbrown.com/ https://sheldonbrown.com/
  • srg0 5y ago
    I don't have a reference, but I feel it's important to find something as recent as possible. Bike geometries, MTB bike geometries in particular, have changed in the last 10 years. And full suspension became mainstream.
• geocrasher 5y ago
  Wider tires are not slower. They are heavier. Heavier tires are slower than light tires because they take significantly more energy to get them up to speed.
  • toxik 5y ago
    In particular their inertia is higher, and the tire is the worst place to put heavy things physically speaking.
    • carl_dr 5y ago
      Not disagreeing with you at all - it is true. But for most people, whether or not you went to the toilet before starting your ride, or had that bit of cake at the cafe stop, has a bigger impact than the additional grams on the tyres.
  • wiredfool 5y ago
    Yes, but the effect is rather small, because the rotating mass is small compared to the combined mass of bike and rider. Also, a typical trick is to go to a smaller diameter wheel and a larger tire, so that the handling and moment of inertia are similar. For example, I’ve got two rim brake wheels, one 700c 16 spoke aero front wheel with a 23mm tire on it, and one 26” 36 spoke tandem/mtb front wheel with a 44mm tire, and the difference in weight is 200g. (1200 vs 1400) Even on the road bike, that’s only a 0.4% difference. (Not that they’re compatible wheels, it’s just the only decent comparison I have on hand)
  • thrwyoilarticle 5y ago
    This is not the conclusion the article reaches.
  • deleted 5y ago
    [deleted]
• MarkusWandel 5y ago
  Cheap tires are slower. Reliable tires are slower. It's obvious from the pictures that the fatties they're testing are special, with paper thin skinwalls. I can totally see that a high performance fattie would be just as good as a high performance narrow tire. It's the inelastic deformation of the tire casing (and inner tube) that eats power. Unfortunately thin-walled high performance tires are also delicate. I've seen people ride tires that can't even survive a couple of kilometers of dirt road.
  • wiredfool 5y ago
    I’ve ridden their extra lights into some pretty ridiculous places, and commuted on them in a city, and they’re as trouble free as any other tire I’ve had. (In about 7k miles) I would recommend taking them on technical single track, but they rock for any sort of road riding. They’re certainly fine for the gravel I’ve seen. (And by trouble free, I mean no flats that I can blame on the tire or some damage to it. I’ve had one slow leaky valve that I had to change on a ride. I’d normally get a flat every 1-2 thousand miles or so with my older tires)
    • londons_explore 5y ago
      The real test for a city is how many hypodermic needles and smashed bottles can you ride over before being stranded by a puncture in a not-so-nice area of town at night...
      • asdff 5y ago
        This is why I ride gatorskins
        • londons_explore 5y ago
          Hypodermic needles go straight through gatorskins.
      • wiredfool 5y ago
        My old narrow tires would tend to collect cuts in the tread, sidewall cuts, and other damage. After a thousand miles or so, I’d tend to be able to see the cords in some of the cuts, and I’d occasionally dig bits of glass or stone out of the rubber. I just don’t see the same sort of damage after 3500 miles on a pair of 650x42 tires. I’m not generally riding over needles or goat heads, and I avoid broken glass as much as possible.
• japanuspus 5y ago
  A great source of data on bike tires is [0], which has been doing systematic tests on a dedicated test rig for many years and appears to be independent of any tire manufacturer. After finding this site a few years back, I bought a high-pressure floor pump and Schwalbe Marathon tires for all the commuter bicycles in the family. Haven't seen a flat tire since, even though we have four bikes on the road almost every day. [0]: https://www.bicyclerollingresistance.com/the-test https://www.bicyclerollingresistance.com/the-test
  • oliwarner 5y ago
    They're great tyres for commuting but they're so heavy. When you swap back to regular or race tyres your bike weighs half as much. Again, I'm not saying they're good tyres, but perhaps best if you have a spare wheelset so you can keep a "fun" set for the weekend.
  • alanfranz 5y ago
    I love Marathon Supreme tires. They're lighter but I haven't seen a puncture on them; on the other side I experienced breaks in their sides (probably because of clipping a sidewalk or other object) twice. I usually ride 32mm or 35mm. You can reach a decent pressure and still ride comfortably.
• wiredfool 5y ago
  There is another article with a newer batch of tire tests here. https://www.renehersecycles.com/bq-tire-test-results/ https://www.renehersecycles.com/bq-tire-test-results/ Basically, they looked at even wider tires 40+mm and they still aren’t any slower.
• dnhz 5y ago
  I don't believe it. When I had a cheapo mountain bike, I could hear the tires on the road, especially at higher speeds. With my current road bike, the tires are a lot quieter. That noise translates into lost energy, including lost energy that can't be heard. Sure the bikes differ a lot, but the difference in rolling resistance is stark to me. The road bike also can roll for a lot longer a distance.
  • msandford 5y ago
    It sounds like you haven't read even a paragraph or two. They're talking about road slicks vs road slicks, not mtb tires vs road tires.
    • dnhz 5y ago
      I read it. But I didn't think there would be a difference between knobby and non-knobby tires compared to the changing width.
  • discreteevent 5y ago
    Mountain bike has knobbly tread. This article is taking about wide smooth tires.
• catchmeifyoucan 5y ago
  Maybe I'm missing it, but what was their testing methodology?
• mastrsushi 5y ago
  Brought to you by the annoying bugmen in the street you wish you could run over as your SUV squishes their $3K Trek.
• jmilloy 5y ago
  I think folks might be interested to consider some of the other myths and tests in the series, such as: * Titanium is ligther than steel * Fenders slow you down * Stiffer frames are faster * Disc brakes work better than rim brakes * Higher tire pressure is faster * Bigger wheels roll faster https://www.renehersecycles.com/category/myths-in-cycling/ https://www.renehersecycles.com/category/myths-in-cycling/ For more nuanced tire testing and results, check out these two more recent articles * https://www.renehersecycles.com/how-we-test-tires/ https://www.renehersecycles.com/how-we-test-tires/ * https://www.renehersecycles.com/bq-tire-test-results/ https://www.renehersecycles.com/bq-tire-test-results/
  • alanbernstein 5y ago
    These are interesting articles, but in https://www.renehersecycles.com/myth-12-disc-brakes-work-better-than-rim-brakes/ https://www.renehersecycles.com/myth-12-disc-brakes-work-bet..., it just says outright "Many rim brakes for wide tires are too weak to do this quickly, so in the rain, you end up with almost no braking power at all." It's not a myth, it's just conditionally true.
    • masklinn 5y ago
      > It's not a myth, it's just conditionally true. Sounds to me like it’s generally true, and conditionally not: in good condition with thin tires on a metal wheel good rim brakes can be better than disc. Je general case is thus that you’re better off with disc as default.
      • jacquesm 5y ago
        We have a pretty wide collection of bikes, and all of them are in tiptop shape. None of the bikes with rim brakes have the same kind of stopping power as the disc versions. They don't even come close. Maybe there is an ideal bike somewhere that can outperform any of the disk brake systems that we have but if it exists I haven't seen it. Ever. Of course this is still 'anecdata' but I've seen a lot of bikes. The people that still seem to push for rimbrakes here in Europe are typically semi-pro or pro cyclists, who may or may not have valid concerns regarding injury due to the disc edges being too sharp (they are now usually chamfered to allay this).
• WalterBright 5y ago
  I'm a mechanical engineer and I never would have guessed this. Kudos for doing testing to see what's actually true.
• elihu 5y ago
  > These suspension losses are mostly absorbed in the rider’s body. Imagine a bean bag that drops on the ground without bouncing back – all the energy is absorbed by friction between the beans. The human body works similarly. Studies by the U.S. Army found that the more discomfort vibrations cause, the more energy is being absorbed. And the amount of energy that a vibrating human body can absorb is significant – the U.S. Army’s study measured up to 2000 Watt! Huh, that's a lot. About 3 horsepower. I don't know what the test setup for that is like, but I'm glad I wasn't the test subject.
• ehnto 5y ago
  CyclingAbout has some great experiments in a similar vein. You can scroll to the experimemts section here: https://www.cyclingabout.com/article-directory/ https://www.cyclingabout.com/article-directory/ He has a great one about aerodynamics which touches on tire aero as well as luggage and clothing aero. Most of the perspective is around bike touring but it's a fantastic resource. He has dozens of guides too and a comprehensive YouTube touring channel. He does all this stuff while perpetually touring for years, so you know it's from real world experience on the bike.
• rhn_mk1 5y ago
  > the air inside a wide tire doesn’t add weight This is true, but it's not weight that matters for acceleration, it's the mass, which that paragraph gets confused about. The air inside does definitely have a little mass. The difference in mass between wider and narrower tires does have some effect on handling, even if not on acceleration.
• rmoriz 5y ago
  While this article targets road cycling, from my own casual city cycling experience I strongly recommend wide tires. They forgive much more rider errors and slip less in any case. I personally use 60mm (60-622) Schwalbe Big Apple tires on my 17 year old Utopia Velo steel bike. Make sure the wide tire fits the frame, some city/holland type bikes can only fit some 40ish mm tires.
• zrav 5y ago
  Tangentially the same is true for mountain bikes to a degree, and for a reason not mentioned in the article: Wider tires (run with lower pressure) cope better with uneven or soft terrain. This can easily be verified by riding different tires on grass, sand or deep gravel. On the other hand, on smooth and hard ground wider MTB tires do indeed have higher resistance. This was experimentally documented by the German "Bike" magazine.
• amagumori 5y ago
  ok, so i'm curious how people feel about this, but i believe, for road riding, wider tires actually do make you faster, to a point of diminishing returns around 32c, because of cadence. when you hit a bump with high PSI / road tires, your wheel bounces, you're momentarily unweighted from the pedals, and that means your cadence is interrupted. anyone who has raced cyclocross knows; there's a LOT of skill involved in applying pedal strokes at just the right times to absorb bumps while also continuing to apply power, and it's way less efficient than just riding clipless on a freshly paved road. every bump "resets" your muscle contraction cycle, and after a bump, you're often not at the right crank position to apply a hard, sharp pedal stroke to try to catch up. i believe a ton of efficiency is lost through this biomechanical effect on cadence alone, and that's saying nothing of how much energy you lose in the transfer of forward momentum to an upward bounce impulse.
• pombrand 5y ago
  Wider tires are still slower BEYOND A CERTAIN SPEED as drag increases. Furthermore tire rolling resistance test are done on a bumpy surface, and 25 mm tires > 28 mm.
  • nchie 5y ago
    >tire rolling resistance test are done on a bumpy surface Which ones are? The ones at bicyclerollingresistance.com aren't road-like-bumpy at least, and that's the most commonly cited page I know of for rolling resistance.
• james_woods 5y ago
  What about aerodynamics? https://www.swissside.com/blogs/news/back-to-the-wind-tunnel https://www.swissside.com/blogs/news/back-to-the-wind-tunnel
• dncornholio 5y ago
  It's not about drag or friction, it's about weight. Wider tires are heavier. Which is a big no no in professional cycling where every milligram counts.
  • suprfnk 5y ago
    The article mentions this, and concludes that the weight doesn't matter as much as people seem to believe: > Wider tires are a little heavier than narrow ones. The difference is smaller than many cyclists imagine – the air inside a wide tire doesn’t add weight – but a wide tire has a little more rubber and casing. Won’t this make the wider tires harder to accelerate? The answer is “No.” > The reason is simple: Bicycles don’t accelerate very quickly. Even a professional bike racer’s power-to-weight ratio is far less than that of the slowest economy cars, and those don’t exactly push you back in the seat when you floor the throttle. Bikes don’t accelerate fast enough for small changes in wheel weight to make a difference. > That is why professional sprinters can use relatively large wheels (which inherently are heavier) and still win races. The UCI requires a minimum wheel size of 55 cm, yet racers use 700C wheels that are 10 cm larger than required. If wheel weight mattered as much as most cyclists imagine, then pros using the smallest wheels would win every race. And yet, even though many have tried smaller wheels, all have returned to 700C wheels – probably because the larger wheels handle better due to their optimized rotational inertia. (But that is a topic for another post.)
    • dncornholio 5y ago
      Ah when I mentioned professional cycling I actually was specifically thinking about mountain climbing. I don't follow cycling much except the Tour. The article didn't mention anything about the climbers, they only mention flat road physics.
  • globular-toast 5y ago
    Actually due to the UCI imposing a minimum weight, they have a fair bit of weight to play with. It's possible to make a bike significantly lighter than the minimum, so they could, for example, choose to make the frame super light to compensate for the weight of the tyres.
• fartcannon 5y ago
  Do they account for weight? This reads like marketing material, not science.
• timwaagh 5y ago
  Case on aerodynamics is weak. I realize their analysis might make sense for extreme endurance events, but they don't generalize to road cycling. They did not test at common race speeds for cyclists. It's 5 watt at 30km/h. That might mean 14 or so watts at 50km/h. It doesn't seem like much but that's significant enough in a road race. And then there are sprints that take place at 60-70km/h