Choosing Your Tires

We’ve experienced a profound revolution in road bikes in recent years: It used to be that to go fast, you rode narrow tires and pumped them up to the maximum pressure. If you wanted more comfort, you used wider tires and (maybe) lower pressures, but you knew that you’d be slower.

Now we know that comfort and speed aren’t opposed, but inextricably linked: A bike that absorbs shocks better rolls faster. Narrow tires don’t have any speed advantage, and inflating your tires to the maximum often makes your bike slower.

But what does this means in practical terms, when it comes to choosing new tires for your bike? Do you need to get a new bike with clearances for ultra-wide tires? Or is there a way to benefit from the “tire revolution” on your existing bike?

The simple guidelines below are based on more than a decade of research into the performance of tires, and they’ve proven themselves on the road time and again.

Supple Casing

The most important part of the “tire revolution” is the supple casings. In the past, we thought that supple casings and wide tires didn’t go together well, because supple, wide tires have to be run at relatively low pressures. Now we know that lower pressures don’t make tires roll slower. And that makes a supple casing better in the two important areas of tire performance: A supple casing has less resistance as it flexes (hysteretic losses) and it transmits less vibrations from the road (suspension losses). It’s a win-win scenario.

Compared to the casing, all other factors – width, tread thickness, weight, etc. – are of minor importance. In Bicycle Quarterly‘s tire tests, the five fastest tires ranged in width from 24 to 36 mm, but they all had one thing in common: a supple casing. In practical terms, this means that a supple 25 mm-wide racing tire will be more comfortable and faster than a 42 mm touring tire with stiff sidewalls.

So don’t fret if your bike can only fit relatively narrow tires. Just get the best, most supple ones you can find, and enjoy most of the benefits of the “tire revolution”.

Width

When in doubt, use wider tires. At least up to 42 mm, wider simply is better. More grip, more comfort, same speed, fewer flats. What about the aerodynamics of wider tires? In our testing, both in the wind tunnel and on the test track, we found the effect too small to measure. And when you factor in the greater shock absorption (lower suspension losses) of the wider tires, it’s likely that any small increase in wind resistance is made up by the smoother rolling of the wider tires. On smooth roads, it comes out the same, on rough surfaces, wide tires are demonstrably faster.

Of course, you’ll have to work with the clearances of your bike. Don’t try to squeeze the largest possible tire in there with just a hair’s breadth of clearance. Your tire may “grow” with age or your wheel may go slightly out of true. I recommend a minimum of 3 mm clearance all around the tire. When in doubt which tire will fit, go with a slightly narrower one. If you find that you have more clearance than expected, get the bigger size the next time around.

Wheel Size

When you get a new bike, wheel size is an important consideration. Smaller and/or lighter wheels will be more nimble, larger and/or heavier wheels will be more stable. Ideally, your bike is both stable and nimble: It should stay faithfully on a chosen line, but it shouldn’t resist if you want to change its trajectory. How do you achieve that?

The forces of trail and wheel flop cancel each other, especially on a bike without a front load. That is why the wheel size plays such an important role – you can’t really compensate for a front wheel that is too large or too small.

The bike industry is only slowly waking up to this. Too many gravel bikes still come with the same 700C wheels that you find on racing bikes with much narrower tires. Smaller 650B wheels are a better choice for wide tires – from 40 to 50 mm –  and for even wider tires, I prefer 26″ wheels. That way, you can enjoy the nimble feel of a good road bike and the surefootedness of wide tires…

If you use ultralight carbon rims and superlight tires (like our Compass Extralights), you can go up one wheel size. The larger diameter compensates the light weight to keep the rotational inertia in the “optimum” range.

My “dream bikes” are equipped with either 650B x 42 mm tires (left) or 26″ x 54 mm, depending on whether they will see mostly paved or mostly gravel roads. But in practical terms, I am perfectly happy on a bike with 700C x 32 mm tires (right), provided the tires are supple performance models and not sluggish “touring” tires.

The importance of supple casings isn’t a new discovery. For almost a century, professional racers have ridden supple, handmade tires, no matter whether the fashion was for 30, 20 or now 25 mm-wide tires. In fact, tires are the only thing that hasn’t changed significantly on pro racing bikes during the last 70 years. You could put Fausto Coppi’s tires on Christopher Froome’s bike, and he’d never know the difference.

Outside the pro peloton, the importance of supple tires was largely forgotten as riders became more concerned about flat resistance than the joy of gliding along on a cushion of air. Only recently, supple clinchers have become available that offer the feel and performance of great racing tubulars, but in much wider widths.

Speaking of flats, that is the one drawback of staying with narrow tires. Since they run at higher pressures, they are more likely to puncture. And yet, in my experience, the fear of flats is often overstated. On the beautiful backroads that offer the best cycling experience, flats are relatively rare.

Debris accumulates where cars don’t go, hence you get so many flats when riding on the shoulders of busy highways. On backroads, you ride in the traffic lane (but with little traffic, you don’t bother anybody), so there isn’t much debris that could puncture your tires.

downhill

To summarize, you don’t need a new bike to enjoy the “tire revolution”. For your existing bike, choose tires with supple casings, and use the widest model your bike can fit with safe clearances. And when it’s time to get a new bike, consider getting a bike designed for wider tires and perhaps smaller wheels to get the performance of wide tires with the nimble handling that makes a good racing bike so much fun. It’s that simple!

More information:

Photo credit: Goggles & Dust / Brett Horton Collection (classic racers).

About Jan Heine, Editor, Bicycle Quarterly

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Compass Cycles, that turns our research into high-performance components for real-world riders.
This entry was posted in Testing and Tech, Tires. Bookmark the permalink.

43 Responses to Choosing Your Tires

  1. Dan Eldredge says:

    Jan,

    You did not mention fenders. Do you recommend more than 3mm between the tire and a fender?

    • Good point! Between tires and fenders, you ideally want about 20 mm. That allows you to ride on gravel roads with confidence and little risk of fender collapse. When you build up the bike, the clearances look huge, but once you put a nice fender on it, it looks “just right” – see my “Mule” below.
      Mule Bike fender clearances

    • Peter says:

      From experience: 45mm mudguards (Velo Orange) will clear 35mm Jon Jon Pass tyres, look great and work well IF the road is clear (wetness is no problem).

      Clearance is inadequate when there is debris like small twigs, wet blossoms etc on the road. Next autumn I’ll change to 28mm GP4000 tyres because of this.

    • Han-Lin says:

      If there’s no room, you can use a down tube fender or change the fork.

      I have a Devinci Podium. To have at least 3mm of clearance, the maximum width for the front is 25C and the maximum for the rear is 28C. If a 28C tire is installed on the front, there’s 1 to 1.5mm of clearance. I could even hear sand coming through the gap.

  2. Ian Michael Yovdoshuk says:

    Jan, how do the merits of larger tire~650b wheels you speak of apply to frame sizes larger than 58cm?
    I ask this because in the wealth of facts, figures, and substantiated opinions you share with us interested persons, there seems to be an absence of frame sizes used in creating all of this data. I don’t believe anyone could answer this better than you Jan. 🙂

  3. Rick Thompson says:

    Any thoughts on scaling the wheels to the size of the frame? I’m 6’4″ and 200 lb, my new frame is being built for wide 700C tires (thanks to Compass there are good choices now at this size). I admit the main reason is aesthetic, the smaller wheels look wrong to me on a big frame.

    • Good question! Wheel size should be chosen for the handling you want, rather than aesthetic ideas. In any case, aesthetically, a 700C x 23 mm tire has the same diameter as a 26″ x 2.3″, so there isn’t much in it. The big question is whether taller riders need a bike that handles differently – Lennard Zinn suggested this when we interviewed him for Bicycle Quarterly… If tall riders need bikes that are more stable, then perhaps going with larger wheels and bigger tires makes sense.

      • John Duval says:

        I think there is a relationship between either the height or length of the bike and how much wheel inertia is acceptable. I am 2m tall, but my bikes are low and long for someone my size. Between 650b, 700c, and 29r, I like them all on smooth surfaces, but as things get rough, the smaller wheels feel like a struggle, and larger wheels feel more flowing. I think a long and tall bike can’t change directions as suddenly, so more stability is simply proportional to the nature of the movements.

    • Han-Lin says:

      Look up Johan van Summeren. He’s 6′ 5″ and his frame didn’t look that bad. Maybe it’s because he used a longer stem, wheelbase, and top tube which kept his centre of gravity low.

  4. Brian Roth says:

    I think there might be an error in the following sentence: “Speaking of flats, that is the one thing you give up if you stay with narrow tires”. I’m interpreting ‘giving up’ flats as enhanced puncture protection. It seems to contradict the sentence that follows that states that higher pressure tires (i.e. narrow) are more prone to flatting….

  5. Rider X says:

    >The most important part of the “tire revolution” is the supple casings.

    If being just being more supple is the answer, why do you use a cross/bias ply rather than a radial ply in your the tire carcass? It is my understanding that radial plies are much more supple. In vehicles radial plies are lighter and have better fuel economy than a cross ply, furthermore cross ply tires have a more rigid sidewall, while radial tires have a more supple sidewall.

    • Many companies have tried to make radial bicycle tires, including Panaracer, but they all have run into problems. Theory and practice don’t always align, and Compass will always prefer what works on the road over what should work better in theory.

      • Rider X says:

        Its seems like it could be such a good avenue to take tire construction, I am curious, what makes radial ply fail in real world applications? I actually rode one of the ill fated trials, an UItremo R, that one happened to develop lumps (carcass separation) within a short period of time.

  6. Dave Williams says:

    Wondering if you tried 650B wheels on your Diverge test bike. If you did, how did it change the handling and how large a tire were you able to run? I’ve been toying with building up a set for my Diverge in order to run fatter then the Bon Jon Extralights, which by the way, are a fantastic tire!

    • Didn’t run the Diverge with 650B for two reasons: 1. we didn’t have 650B wheels available that fit the bike; and 2. the clearances on the side of the fork would be too tight to put really wide tires on that bike. But I hear that a new version of the Diverge is in the works…

  7. Han-Lin says:

    How do you think 36 inch wheels with narrow tires would compare to 650B wide tires? 36ers tend to be custom made and designed for taller riders. There’s a video of a 36er being used to climb stairs. I like the idea of commuting on quieter streets since they’re safer.

  8. kww says:

    I have 3+ years running Barlow (700×38) & Snoqualmie (700×44) tires. They are very durable and wear well. I would challenge you to come up with an inner tube that holds air as good as these tires are. The Schwalbe tubes usually need a pump up at least every 2 days or so (I have tried both valve types).

  9. Ty says:

    I do have the Compass 32″ tires in extra light on my Salsa casserroll and love them, but what do I do about my Bike Friday Tikit and Brompton? Both have 16″ tires! 😜

    My question is slightly tongue-in-cheek as these are my commuter bikes and I run Marathon Plus Supreme a on them for flat protection.

    That being said, I have commuted with my Rando bike more than a few times and gotten no flats with my tires with supple casings and that is on debris-filled roads in the financial district of San Francisco. One stretch was over a month when the Tikit was in the shop and I had not yet bought the Brompton. So even in a flat prone area, these tires hold up very well and provide a very comfy ride.

    You might not think you have the market, but I know plenty of rando riders who commute with small-wheeled folders, particularly Bromptons. In fact, there was a pretty spirited Brompton thread in the Rivendell users group forum not long ago. I can assure you there would be plenty of buyers, myself included.

    Ty Smith
    San Francisco Bay Area

    • Zach says:

      I second the desire for supple wide tires for the Brompton! It’s a great little bike but the tire options are sub par!

    • Alex says:

      Ty, I’ve been a Brompton fan & ‘user’ since 2000 (& used to have a Bike Friday Pocket Rocket), & I understand your enthusiasm.

      I think folding bikes are usually used in scenarios where flats are more annoying than they normally are (commuting, ‘last mile’ transportation etc), & I believe small-diameter tires are more susceptible to flats because the foreign bodies that get stuck in them can be pushed into the tire much more rapidly than with large diameter tires (the tire rotates faster).

      I would thus argue that a more important lobbying effort should be directed towards the Brompton company itself, to convince them, based on Jan’s and others’ research, to redesign the Brompton frame to allow 42mm (& increase the inside rim width). Then, I believe, a Compass (or any other maker) 42-349 would make a lot of sense, as the lower pressure required would also help reduce flats, no to mention all the other benefits of wide tires.

  10. A Escolier says:

    Mon cher Jan,

    Je suis français et franchement ces gros pneus are just ugly. Je suis une espèce de parnassien, l’art pour l’art, et je continuerai à rouler avec des pneus pleasing to the eye. Nothing makes me happier than pumping up my narrow tires to the maximum pressure.

    Talking about the Révolution, in our family when we mention that period we say ‘les regrettables évènements de 1789’. This summarizes quite nicely what we think about the Révolution or any revolution.

    Cheers

    A Escolier
    Paris, Ile de France, France

    • Aesthetic preferences are important, and I can see the appeal of a racing bike with narrow tires. But as they say, beauty is in the eye of the beholder. For me, the classic randonneuse of the 1940s evokes the spirit of the randonneurs who pushed their limits on the wonderful roads of the Alps and Pyrenees, and I now find those bike rather beautiful.

      Fortunately, we make supple 26 mm-wide tires for traditionalists like you, so you won’t be left out of the “fortunate events of the last decade”, which have made cycling so much more pleasant.

    • marmotte27 says:

      Langue in cheek, très funny.
      Mais sérieusement, seeing a randonneur bike with fat tires for the first time on the cover of BQ in spring 2011, I really thought, what’s happening now? It didn’t fit with my mental image of a performance bike on skinny tires. But quite quickly I was won over, and what helped me along was the totally convincing explanation for those fait tires. Form follows function.
      Contre-exemple: Looking at fat- tubed sloping carbon frames never felt right, inspite of the claims that they were stiffer and faster. I had no counter arguments, it just didn’t convince me, neither rationally nor esthetically. Same goes for skinny jeans by the way…

  11. Cecil says:

    I know there’s much variation in rims—and, I imagine, some small variations between batches of tyres—but I think it’d be helpful for those of us contemplating upsizing tyres if you could publish the tyre widths as they mount on a standardised rim, eg, the HED Belgium+ and/or Pacenti rims that you sell. I’m thinking of trying 650b x 38 mm Loup Loup XL on my Domane SLR. (Currently running 700c x 32 mm Stampede Pass XL—really, I preferred the 35 mm Bon Jon Pass XLs I had on my previous bike but they won’t fit the Domane.) Before making the switch to 650b in the search for a wider tyre, I need to to know their actual installed width on the HED Belgium+ rims I would use.

    • We list the actual widths of our tires on 23 mm-wide rims (outer width) on our web site. As you say, there is a lot of variation based on rim width, standard vs. superlight casing, tubes or tubeless, and even who is measuring… Ideally, a millimeter or two shouldn’t make much of a difference – your tires should be plenty wide and your bike should have plenty of clearance – just like I’ve never bothered to measure the tires on my car, which are nominally 185 mm wide… Of course, in the real world, many of us ride bikes designed for narrower tires than we’d like to use now, which is why clearances tend to be awfully tight.

      To answer your question, the Loup Loup Pass will be very close to 38 mm wide on the HED rims.

    • morlamweb says:

      The Compass Rat Trap Pass standard-casing “26 x 2.3” tires measure at 52 mm on my 21-mm clincher rims. That was shortly after installation; I should re-measure them now after a couple of months of use.

  12. Ian says:

    What about rim width vs tire width? My px-10 can fit a tire wider than I have dared put on my 19mm outer width rims. How far can you push that?

    • Rim width doesn’t really matter much with supple tires – within reason. On 19 mm (outer) rims, you can run at least 38 mm tires. As always, it depends a bit on the tolerances of the rims…

    • Be careful of the pressure. There are some 35mm tires out there that say on them that they can go all the way up to 90 psi. That would probably crack most 19mm rims, think about how much more force that is than 90-100 with a 23mm tire. (in addition to ridding like crap, for more than a few reasons the bigger the tire the less pressure you need)

  13. Conrad says:

    There are a lot of good old 26 inch mountain bikes out there, deemed obsolete, that are practically being given away. Put on some drop bars and rat trap pass tires, and you have a wonderful allroad machine on the cheap. Thanks for making those tires!

    • morlamweb says:

      I agree. My one bike started it’s life as a mountain bike: a 1987-ish GT Timberline Al Terra bike with a rigid steel frame. Not a top-quality frame by any means, but it’s reliable. As a mountain bike, it has clearance for wide tires as a given. I use Rat Trap Passes on the bike, as noted above (and in my comments to earlier posts), with metal fenders, and it clears ’em both handily. I haven’t measured the clearance, though I wouldn’t use tires much wider than say 54 mm with fenders; sans fenders – though I wouldn’t dream of riding a non-fendered bike nowadays – it could easily clear 60 mm+ tires.

      • Conrad says:

        Nice. I think the biggest performance limiter of those bikes, by far, are the clunky knobby tires. The rat trap tires transform them. Getting adequate fender clearance is a bit more tricky though. I have been happy with the SKS P 65 fenders. Coverage isn’t quite as good as a Honjo but I would hate to crumple the Honjo, especially if you are riding trails.

      • I’d be more concerned about injuries due to a fender that goes into the fork crown and locks up the front wheel. Stiffer fenders, like the Honjos, are much safer in that respect than flexible plastic fenders…

  14. Jonas says:

    Interesting blog post, that triggers me to share my considerations regarding 650b conversion.

    I’m currently running 700×42 on my gravel/allroad bike and is considering making a 650 conversion, however i’m not sure I can much wider. There might be room for 48mm on the front, but not much more on the rear, maybe 44. I like to go as wide as I can. I’m using my bike for almost everything: road, gravel, cx, and singletrack. Wide tires are really nice for that kind of riding.

    So the question is, is it worth it?, I have toe overlap with the 700×42, something that is a bit annoying on singletrack, but not many other riding situations. That would go away on 650b (i hope)

    Would I actually gain anything going from 700×42 to 650×44/48. Will the contact patch actually grow, as the tire is smaller? I might get a more nimble bike on the road, but would rollover suffer too much on singletrack and gravel? Should I have other considerations, besides what I have already mentioned, and the fact that the geometry of my bike is changing.

    • The geometry change with the (slightly) smaller wheels is less of a factor than the rotational inertia. If you feel your bike is too stable with the big 700C wheels, then it’s worth considering smaller wheels. Wider tires obviously will have much more air volume, too.

      The other considerations are minor by comparison. The contact patch is determined by tire pressure and the suppleness of the sidewalls much more than by wheel diameter. The smaller wheels will roll just as fast – we tested 700C, 650B and 26″ wheels on rumble strips, and found that even on that extremely rough surface, all three wheel sizes rolled at the same speed.

  15. Thomas Klein says:

    I’ve tried a number of supple road tires but they get flats way too often. I know I’m sacrificing some speed by running hard tires near max pressure but not having to fix flats for months and the peace of mind that comes with being able to tell if my tires need air by feel is completely worth it.

    • I’m sorry to hear about your experience. It all depends on where you ride. Especially the shoulders of busy highways accumulate all kinds of debris – especially the steel wires from shredded truck tires…

    • Jacob Musha says:

      Thomas – what was causing your flats, and what tire width were you using? I think there really is something to the “wide tires at lower pressures get fewer flats.”

      I’ve been doing almost all my riding on Compass tires for the last 7 months (about 5000 miles) and the only time I got flats was in the winter when they cover the roads with a sand/gravel mixture that has small pieces with really sharp edges. In that case, a thicker tire or tire liner is needed to stop flats.

  16. Gert says:

    There are four factors at least behind the tires I use, and will use.
    Puncture resistance is one. On my winter bike I use Schwalbe Marathon Supreme even though they are heavy and slow, because I hate being cold and wet standing with a flat with numb fingers, and training is not impacted, it is just harder. In the spring, summer and early autumn I use Swalbe Kojaks most of the time because I feel To much frustration puncturing more often on my Compass tires, even though the time gained may be greater, than the time lost to more punctures, which happen mostly in wet conditions on bicycle paths (in Denmark, where small flint stones are everywhere), so I save my compass tires for dry conditions or in other countries.

    I choose 700C, because the bikes I have are 700C. But for my next bike I would also choose that, not because I am 6’5″ and believe that most things on the bike should be relative to size, but more because more cheap wheels are available in 700C.

    Weight is part of it. I have ridden both Stampede Pass and Bon Jon Pass, and I do not feel any big gain in the 3mm difference and Stampede Pass is lighter.

    The price of tires is also important, so I use the cheaper tire most of the time and save the expensive ones for specific events.

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