Editor’s Note: We have noticed that there is a trend toward making “all things gravel” wider, bigger, and more burly. Take for instance the suspension forks, dropper posts, and of course, wider tires and rims bordering on mountain bike sized rubber. While seeing what is considered “gravel” change is exciting, we were left wondering why we aren’t seeing more “skinny” stuff. Things like 30mm-35mm tires, maybe even disc road bikes are something viable here. Well, we aim to do something about this dearth of “slimmer” gravel travel information. We have a set of 35mm tires from Hutchinson and in this post, Grannygear explores the ways of the newer, plumper road offerings and how that might work out for gravel travel. Enjoy!
A Look At The Slimmer Side Of Gravel: Road Style – by Grannygear
I ride a lot of road miles and I do that on a dedicated road bike, although most of my gravel bike rides include some pavement as well. My local area has some very good road riding, certainly better than the local mountain biking possibilities and a good bit better than any gravel stuff too. My most recent road bike purchase ticked some important boxes for me and one of those check marks was room for at least a 30mm wide tire.
I am a fan of wide, poofy tires run at lower pressures. It made MTB riding better when rims became wider, allowing us to run our tubeless tires at pressures down into the low 20s (even at my 190lbs) and not lose steering accuracy. It was marvelous really, what that did for off road riding. Traction went up, comfort went up, techy climbs got easier, and it was still fast. A win for our team. I ride 27.5×2.8 tires at 15psi on my Santa Cruz Tall Boy and it would be hard to go backwards from those in this semi-desert terrain I ride.
On the gravel bike I run a 42mm tire at around 35PSI, maybe less, seldom more. Same deal. Complete win on anything that does not require miles and miles of paved riding at higher speeds.
Roadies have been surfing this wider ‘wave’ as well. Road rims, spurred on by tubeless use and the adventure bike craze, have been gaining inner width like crazy. I have two sets of carbon rims, one at 50mm deep, that are as wide inside as I was running on an MTB rim not too many moons ago. So when I was road bike shopping early this year, I knew I wanted to be able to run a big road tire. I knew I wanted tubeless, and I also knew that meant disc brakes. I was curious how that would all play out.
Of late there have been some very credible studies proving that a larger sized road tire running at a lower pressure is very fast, often as fast as a smaller volume tire run at higher pressure, and maybe, depending on the road condition, even faster. Fascinating. The promised perks are pretty enticing: increased comfort, reduced vibration, less concern of tire/rim damage on impacts, and increased traction when cornering. How about the ability to get your road bike into some dirt, easy dirt mind you, but dirt nonetheless, and survive! The drawbacks? Increased weight, both in the tire and the wider rim that should be paired with a wider tire, and the not so easily dismissed thoughts in the back of my mind that bigger means slower.
Now I know this is ridinggravel.com, and I know that a 30mm tire, no matter what it is mounted on, is not a legitimate gravel road tire. But I bet that many of our readers ride a road bike as well as a gravel bike. And as good as a fast gravel bike is, even on the road (surprisingly so), there is still a place for a pure road bike. But what if you could have your road bike and yet be able to dip a toe into some mild dirt? Or take on a broken road without taking your life into your tightly clenched hands as you skitter around thinking this was a really bad idea?
So over the past few months I have been on two sets of tires that measured out to be at least 30mms wide and I thought I would talk about my experiences for those that might be wondering if it is all that and a bag of beans. Here we go.
First of all, what I have been running for a couple of years was a 25mm Continental GP 4000S II. Fabulous tire. I was running it with tubes as it is not a tubeless tire…Continental is yet to jump into that pond…but on a wide-ish road rim measuring 18mm internally, the GP4K tires puffed up to 27mms wide. I was able to run them at 80psi rear, 75psi front with no issues. The wheels I had paired with them were American Classic Argents which IIRC were under 1400g in a non-disc version. It was and is a pretty nice combo.
Going to disc on a road bike adds weight, or at least within the same parts group it does. The wheels will typically pick up 100g. The frames are not affected as much these days, but the disc brakes themselves are heavier. It is pretty close to a pound penalty going to disc, although that is getting a bit better. So we are already fighting weight creep by going to disc brakes. Adding a wider rim and a bigger tire does not help. In order to combat the weight gain I went to a carbon rim on the new wheels. Even at 50mms deep, the disc wheels were still in that 1550g range and I was also curious about the bennies of an aero wheel. As well, the external width of a carbon rim is always wider than an aluminum rim would be, given the same inner width. So my carbon rims were also 27mms wide on the outside, which got me much closer to the final width of my tire, something, I am told, is more aero. Cool.
I have been running all of the tires tubeless of course. One of the things that made me feel better about tubeless use on the road was the ability of a bigger tire on a wider rim to be run at significantly lower pressures. How low? Pretty darn. How about 50psi? Yep. and I am not a small guy. I actually run closer to 55 as an average, but I have run between 45psi and 60psi. Try that with a 23c tire. I would not be so relaxed about road tubeless if it meant 90psi to 100psi or some silly thing like that. Boom.
So how has it been after 1200 miles on 30mm wide road tires?
Speed: As far as I can tell, I have given up nothing on flat or rolling terrain. Now complicating this is the aero wheels, the new bike, etc, etc. I introduced lots of variables. But if it was going to be sloooow and draggy I would have known that by now. And when the road is crummy and rough, it is absolutely faster just because I can pedal with much less concern and more control. I hang with a group of crazy Filipinos that host a twice weekly night ride. The pace varies between pretty fast and ‘daayyuum’ fast with pace lines and sprints a’plenty. I think the deeper wheels help here, but I hang in there, at least as much as my legs allow. Would I be faster on more of a race tire set-up? Yes, I likely would be in this case, but the fact that I am not dropped any more or any less than I was on my other bike with the lighter wheel and tire is significant.
Climbing: Strava lets me know the hard facts. My previous road bike is a custom steel frame, non disc. It is a bit lighter overall than my carbon disc bike and the wheels/tires are lighter. Gearing, components, etc, are similar. I have just as many hilltop PRs on my disc bike with 30’s as I do on my steel bike. As far as I can tell, it has not really made a difference overall. I am not faster and I am not slower when all the factors are considered. There is one situation where I feel I am losing something with the 30’s. On a short, steep, grade, the kind where I am out of the saddle and on the gas hard with my weight transferred forward; as I turn up the watts I believe I can feel the lower pressure, wider tire, push back a bit and drag. Now I could be wrong. But it feels that way, especially if the surface is very smooth. I guess if we spent all our rides sprinting up short, steep, hills covered in smooth pavement then we could be faster on a 23mm tire at 120psi. But we don’t ride like that all the time, or at least I don’t.
Comfort: Oh my yes. My steel bike with the 25’s was actually a smoother ride overall than the new bike with the 30’s. This carbon frame is on the stiff side, vertically speaking. But the difference in vibration, impacts from cracks in the road, potholes, etc, is noticeable with the 30’s. I cannot imagine how good that steel frame would be with a 30mm tire at 55psi. Mercy. Caddy style. Steel bikes are buzzy bees. They transfer a lot of vibration and my steel bike had zero carbon on it (still 17.5lbs WITH pedals). On chip seal roads over long miles I would actually get tense and annoyed from all the vibration feeding up through the bike. Now of course…carbon frame, carbon wheels (no carbon bars though)…yeah, less buzz on the new bike, but the tires mute a lot of that small buzziness and tiny crack impact. Very nice.
Handling: I think that a bigger tire slows down any bike’s response to steering inputs. It also raises your bottom bracket a bit, but we are not talking big numbers here. The 30s feel very planted and calmer. I also rode the carbon bike with 25s (skinny ones) and it felt just a bit more touchy. Cornering is pretty nice with all that rubber on the road. And when your line of choice in the road is suddenly pock-marked at speed, a tubeless 30mm tire is big enough to shrug off most impacts with grace although there obviously are limits to this.
In the dirt: A 30-31mm wide tire at 55psi will be so much better than a 25mm tire at 90psi that you will be amazed. Truly. Now it is still only 31mms wide, but that allows for a more adventurous attitude. Even on this stiff carbon frame, and even with the deep carbon wheels, I can cross dirt patches and meander on gravel sections with much more calm than you would expect. I get much, much, less ‘pinging about’. That road I wrote about in my Ghost Roads post a while back? I always ride it on a gravel bike just cause it is the right tool for the job, but today I pedaled a couple of miles in on the road bike with the 30s. It was pretty okay. In fact I might even try the big loop on it someday, something I would not have wanted to do in the past. There is a fine line there, but the fact I am even considering it is something.
Now I have tried two sets of 30’s on the bike. The first set was from Schwalbe. Their G-One Speed in a 30mm version has that little basketball looking tread to it and is a reinforced tire too. It is what I would choose if I was trending towards truly bad roads or more dirt, both for a bit more grip, but also a more durable casing. However it also rides a bit harshly and I think gives up some speed in the process, although not by much. It also is not the biggest tire when mounted. Yes, it is actually a 30mm wide tire on the rim, but so are my wife’s Schwalbe Pro-One 28mm tires when mounted on an equal width rim and at the same pressures tubeless.
The most recent set of 30’s have been some WTB Exposure 30mm tires. They are a pure slick which is fine for my purposes…better, really…and they are 31mms wide on the same rim as the Schwalbes. I think that these are 60TPI casings which is something new for WTB (typically 120TPI). Not sure I can tell without a direct comparison. They feel pretty fast and all and have been wearing well. I have hit some stuff riding with those crazy guys at night, stuff I heard and felt but never saw…*PAW-TWIIIINGGG*…and so far they are unscathed. I like them, although seeing WTB on the sidewall of my road bike is a bit odd. They seem to be out-wearing the Schwalbes.
Both tire pairs were flawless run tubeless. No issues at all.
So where will this end? In the search for more rubber on our roads, where is that tipping point to where the better no longer outweighs the worse? 32mm? 33mm? 35mm? I am not sure. And really, a lot of that depends on who you are, where and how you ride, and what you require. Heck, I know some riders who have the power and fitness to push a 38mm gravel bike tire along for the road rides and they are never last. Once you get them up to speed they are pretty darn fast. But for my use, on a pure road bike, and on pretty decent roads, I would be surprised to find that anything much bigger than 30mms would not begin to be a loss, both in weight and in drag through the air. I could be wrong, but at some point physics rules. But think how far a leap that really is! I know guys that are still riding 23mm tires on 15mm internal width rims. To get to where I am from there is huge, both in the practical aspect of having a bike that can actually fit a tire that big and having a mind open enough to believe in it and try it.
Disc brakes for road are here to stay. I am not all in love with all aspects of that, but it does allow wheel makers to ‘de-couple’ the rim design from being a braking surface and having to work within the limits of a rim brake’s capacity to clamp over it all. No one I know wants to run a long reach caliper brake. So for good or bad, disc is here to stay. And the interest in a wider use of ‘road’ bikes is promoting frames that allow for biggy tires, even in carbon frames intended for performance riding. It is a game changer in the stodgy world of road bikes, a place that has seen very little change in decades.
Me, I am sold. I might go back to a 28mm that poofs out to near 30mm just to see how that is. The Pro-Ones do that. But if I cannot tell much of a difference speed wise, then why not have more volume at a bit lower pressure?
It’s a brave new world, this bigger tire deal, and I am on the fat bus that takes me there.
About The Author: Grannygear hails from SoCal and spent most of his cycling days as a mountain biker from the formative years of mountain biking all the way up to the present day. His day job is in the tech sector, but he has spent time writing about off road 4X4’s, 29″ mountain bikes, and cycling in general. Grannygear and Guitar Ted have worked off and on together since 2009 after a chance meeting at Interbike. With gravel cycling on the rise, Grannygear has been exploring how this genre’ works in SoCal and now does guest pieces for RidingGravel.com in his spare time.