MATTER of FACT: Tire Management
Tire choice for mixed-terrain, multi-surface, all-conditions riding can be complicated. ‘Can be’ because there’s always the option of ‘going nuclear’ with your tire choice, much in the same way folks tend to do when they purchase SUVs.
"'What if there’s a zombie apocalypse, and we need to be able to drive through and over zombies‽'“
So we have all sorts of people driving around in SUVs that are way overkill for what they actually do day-to-day, and thus waste energy unnecessarily, sometimes flip when a car wouldn’t, yada yada.
Wasting energy in an auto is one thing; lots of folks consider this a mere matter of $$, while for others, environmental impacts are front of mind. Few think about the energy wasted in physical terms at the human scale, because all we do is push gas and brake pedals.
But pushing bicycle pedals brings clarity to the value of energy. We have it, we use it, we want it. Maybe we run out, and we don’t get where we need to get before dark. Maybe the wind is brutal and we wish, WISH, we could get smaller, more aero, CONSERVE ENERGY, MAKE IT.
So yeah, tires are simple enough if we go nuclear, SUV style, and mount something that is mega burly, near impossible to puncture, with tonnes of grip. But while such a tire might once in a while - if ever - find itself in the conditions it’s truly necessary for, the reality is that most of the time it’ll be crap. It’ll be wasting our precious energy, handling like a dumptruck, and wearing out faster than we think it should. It’ll make our ‘gravel bike, way more fun than a mountain bike for lots of stuff’ way LESS fun than a mountain bike for most stuff, because it’ll be a category mistake. Thus, most riders will want to select a tire that actually makes sense for the majority of the riding they do, preserves the feel of the bike that brought them to the format in the first place, and allows them to ‘ride to the tires’ when terrain falls outside the tire’s cone of suitability.
Jake wrote in with a question that gets to the heart of this matter.
Hi!
I’ve followed you for a bit and read a bunch of your stuff on the Tekne website to help while building up a bike I’m working on.
But there’s one thing that I think is a mental block more than anything, that you may have some insight on, regarding tires.
Does a tire like the [Rene Herse] Switchback Hill feel delicate? In choosing tires, despite all the pros and reading I’ve done, in my head it seems like they can’t take the abuse that something less supple can.
Do you ever roll down some single track and think about your tires? Or are you able to shred them with complete faith?
Thanks
-jake
For those unfamiliar, the Rene Herse Switchback Hill is the lightest and most supple 650b x 48mm tire on the planet. Manufactured by Panasonic for Rene Herse, which is run by Jan Heine in Seattle, Washington, the Switchback HIll (SH) is the original high volume supple tire, made possible by the introduction of disc brakes on drop-bar bikes. The tire’s predecessor is the Babyshoe Pass in 42mm, a size commonly used by randonnee riders for almost 100 years. The 650b x 42mm tire is extremely light in Rene Herse’s Extralight casing format, which means it has very low inertia. This makes the tire very quick to accelerate, and a nimble-handling set-up. If you have a bike that rides too much like a truck for your taste, you might wish to try a pair of the Babyshoes on it.
The 48mm SH was a bit of a game-changer when Jan Heine introduced it, for two reasons. First, it bumped volume WAY up versus the 42mm tire, and second, it brought ride height back up to the equivalent of riding a 700c x 33mm tire. While the 42mm Babyshoe dropped ride height to about the same as a 700c x 23mm tire - too low for trail riding on many bikes - the SH allowed for the confluence of perfect ride height for handling AND perfect volume for terrain that actually makes sense to ride on drop-bars. Remember the SUV analogy? Contrast this against a 700c x 42mm tire set-up, which introduces toe-overlap on most bikes, and increases ride height, which is not really ‘stability increasing’.
The SH has a couple key characteristics that made the 650b x 48mm size - which fits a lot of bikes now - pretty darned attractive. It’s a juicy tire, does this mean we can go full-send?
It depends.
The SH in Extralight casing is juuuuust ‘thick enough’ when it comes to interior casing rubber coating to seal up with a normal amount of tubeless sealant. Just. Why? Because the less rubber covering the threads of the casing within the tire, the more supple and lively the tire. When run at low pressures - which are proven to be faster -rolling than high pressures in supple tires - the tire conforms to irregularities in the surface underfoot, which reduces ‘impedance’ - the degree to which hitting stuff slows you down.
It doesn’t make sense to run a SH at 60psi. That makes for a rough ride and cornering grip will suffer. A SH at around 30psi will support the rider’s weight well, feel stable, avoid casing collapse under hard cornering, and withstand significant impacts without bottoming on the rim and puncturing. And at the right pressure, casing tension will be lower than at a higher pressure, which means if the tire glances a sharp rock on the shoulder or side it’ll be less likely to cut.
Getting to Jake’s specific questions:
Does the SH feel delicate?
No, when run are the right pressure for rider weight, it feels like any other good tire. The caveat is that the tire can fool skilled riders into outriding its intended use. This is exactly like light MTB tires; there’s literally no difference in the dynamic at play aside from lugs and no-lugs.
A pro race-level XC MTB tire, such as the tubulars Nino Schurter has been known to use, is a ‘fragile’ tire from an enduro perspective. One can’t take just any line or jump into rock-gardens blindly on such a tire. Its liveliness and positive feel while putting power into the bike comes at the cost of being somewhat puncture prone when smashing into sharp rocks, and threading through tight gaps between rocks. Such a tire will be very capable and reliable in rooty terrain, where sharp edges are uncommon. But in environments with sharp rock, they must be managed; one must ‘ride to the tire.’ I also call this ‘tire management.’
This is a matter of compromise, which, again, is the name of the game when avoiding ‘going nuclear.’ A SW with Extralight casing is a wonderful tire to ride on roads, be they smooth pavement, broken pavement, or gravel. At a compliant pressure, they absorb a significant amount of vibration that would otherwise be absorbed by the rider’s body (read: consume energy), versus a smaller tire at higher pressure, or a same-size tire with a stiffer casing at the same pressure.
If we’re riding a bunch of pavement, and we want to preserve the option of taking on trails, the SH is absolutely a great tire. BUT, we have to be reasonable about our expectations.
Confidence manifests when we anticipate results as the outcome of specific actions taken, and we’re right.
If we hit a trail on SHs anticipating that if we go full-send and clip a sharp rock, we’ll puncture, we’ll dial it back to maybe 85% speed, and ‘ride to the tires.’ Yes, in contrast, we could be on a 27.5 MTB tire, and pretty much send it as fast as we can handle on drops, and pull it off. BUT, the rest of the time we’re rolling around on tires that SUCK.
We’re talking about what will likely amount to hours and hours on SHs where they are fantastic, then minutes where they are still good, but not MTB-tire good. That’s a trade-off I’m happy with. And so is Schurter. He chooses his tires for the whole race-track, not the hardest descent. If there’s a section that is literally unrideable on his light tires, but riding a burlier tire would save him getting off and perhaps 15 seconds, he might go for that heavier tire, IF he wasn’t going to lose 16 or more seconds throughout the rest of the track on them.
Confidence: if thinking that this ‘huge’ tire can surely crush any trail one can ride on drop-bars is one’s starting point, it’s not going to work out. The SH doesn’t have enough material to hold up to full-send on trails, nor does it have anywhere near enough grip to pull off hard braking or cornering. One could easily lose confidence in the tire by going in with the wrong mind-set. The same is true for the Juniper Ridge, the knobby companion to the SH. It’s awesome for riding that is more dirt-biased overall than pavement, but still not a tire to smash into anything and everything on a rigid bike with goofy handlebars.
Do you ever roll down some singletrack and think about your tires? Or are you able to shred them with complete faith?
Yes and no. Early each season, as I get rolling on tire set-ups for the first time in a long time, I don’t yet have my pressures dialed in. I’m uncertain of the capability of my tires, and whether my pressures are right. During this phase of the season I get punctures. I try to avoid overcompensating with too much pressure if I bottom out, and think about whether I was just out-riding the tire, not ‘riding to the tire.’ If I cut the side or shoulder of a tire at a pressure I thought was good, I will likely suspect I had too much pressure and casing tension. So I’ll drop a little and be careful as I test. Riding the same trails on a regular basis really helps move through this process of testing and validating.
Once I’m a few weeks into this process, the answer flips right into ‘no.’ As in, no, I don’t think about my tires while on singletrack. At this point I know what the tires can and can’t do, and how fast I can and can’t hit stuff. So I pick my spots to open it up and shred, and my spots to brake and/or ride light.
When you think about it, this is just like how pro downhill and XC riders race. They NEVER ride as fast as they possibly can on all sections of a course. They ALWAYS hold back in certain sections to protect their equipment and manage their risk. This is the approach that allows riders to develop the skill through time to appear to be shredding at every moment, and to actually survive to the point of becoming professional.
Ultimately, riding drop-bar bikes off-road is an exercise in finesse that is rather unlike a lot of MTB riding being done right now on trail bikes. The whole magic of a good gravel bike is that it feels pleasant to ride on any sort of road, and is capable enough to provide an ‘old-school’ MTB ride quality on trails.
The fact is, back before front suspension came into the game, tire management was huge. Front suspension, then rear suspension changed the equation a little, and mountain biking evolved. As this occurred, MTBs went from being fine to ride from home to trails to totally horrendous to ride on pavement. So people drive their bikes to ride. The gravel bike is a return to the ol’ days, where you can just ride anything and everything. Provided you ride to your tires. Because going nuclear is a lose-lose scenario.
