The Drawbacks of Supple TiresJan Heine
At Rene Herse Cycles, we love supple tires. More than anything else, they have come to define what we do: Bring you the highest performance and greatest joy as you ride your bike. Supple casings makes tires faster and more comfortable – what is not to like?
This post’s headline already hints that, like all great things, supple tires have some drawbacks. They are high-performance parts. We make our Rene Herse / Compass tires as user-friendly as possible – for example, we add a little rubber to the center of the tread to increase their lifespan considerably. But we don’t want to reinforce our tires to the point where it compromises their performance. This means that – like all high-performance components – supple tires require a little extra care.
Supple tires are more flexible, which can make them harder to mount, especially with tubeless-compatible rims. The ‘well’ in the center of the rim is there to allow mounting and removing the tire. It reduces the diameter of the rim, and provides slack to lift the bead over the rim wall. To mount the tire, the bead must be in the well all around the rim (left bead in the drawing above).
With stiff tires, the bead is either inside the well or not. With supple tires, the bead can flex and snake in and out of the well. When that happens, the bead rests partially on the ‘shelf’ next to the well. Then the bead doesn’t have enough slack to be lifted over the rim sidewall. The tire seems incredibly hard to mount. The secret is to go around the tire several times and push the bead into the well in the center of the rim. Then, a supple tire becomes as easy to mount as a stiff one.
Pro Tip: Tubeless rim tape is thinner and slipperier than standard tape and should always be used with tubeless-compatible rims, even when you install tubes. Otherwise, the tire bead will not slide over the edge between the well and the shelf as it seats against the rim wall. Tubeless tape can be a good choice with non-tubeless rims, too, if the tire fits too tightly.
Tubeless tires eliminate the risk of pinch flats, which can be a game changer for riding in really rough terrain. We feel this is important, so we’ve worked hard to make our wider tire models tubeless-compatible.
Tubeless installations work great for 99% of our customers, but the remaining 1% can have trouble. In rare cases, the casing can leak sealant through the sidewall. To keep the casing supple, we keep the rubber coating to a minimum. Sometimes, this can leave the casing a little porous. No problem if you are running tubes, but tubeless sealant can leak through these pores: Make sure to shake the sealant for at least 60 seconds before you inject it into the tire. For the first installation, we recommend Orange Seal, which seals the casing better than other brands. Also make sure you add enough sealant – wide tires have a large surface area and will absorb a surprising amount of sealant.
Sometimes, the tiny pores in the tire’s casing are smaller than the solids in the sealant, allowing the liquid to escape without the solids plugging these microscopic holes. You’ll see bubbles on the sidewall. (Sorry, no photo – in more than 50 tubeless installations, it has yet to happen to me.) If this happens to you, we’ll replace the tire under warranty. The alternative would be to coat all our sidewalls with more rubber, which would make our tires heavier, slower and less comfortable.
Tubeless tires can blow off the rims – independent of which brand you use. This is rarely the fault of the tire, but usually a rim problem. We’ve found that quite a few rims are slightly undersize. When you use tubes, this makes sense – a slightly undersize rim poses no problem, because the tube reinforces the joint between rim and tire. An oversize rim would make the tire difficult or impossible to mount. That is why the tolerances of rims are usually negative (smaller is OK, bigger is not). Some OEM rims appear to be intentionally undersized, to facilitate tire mounting in the big assembly plants for production bikes.
When you mount your tires tubeless, there is nothing reinforcing the joint between rim and tire. Even a slightly undersize rim can cause a tire to blow off. This problem is greater with supple tires: A stiff tire will stay on a slightly undersized rim, because its bead has to lift over the rim edge for quite some distance before it blows off. A supple tire can lift across the rim edge in just one place, because its sidewall is more flexible. This can lead to consternation among customers: “This rim worked with my last tire, and now you say it’s undersize?” What happens here is simply that the tolerances for the fit between rim and tire are tighter for a supple tire: A rim that (barely) works with stiff tires may be too far out of tolerances for a supple tire.
Fortunately, you don’t have to replace your rim just because it’s a bit undersize. Build up the rim bed with extra rim tape – use thicker ‘Gorilla Tape’ if the fit is very loose – and the tire should seat fine. You want a slightly tight fit of the tire on the rim, so you can barely mount the tire by hand, or with some light tire lever action. The tire should seat when you inflate it with a standard floor pump. If you need huge blasts of air from a compressor to seat the tire, the fit is too loose.
Don’t try to seat a tire that doesn’t fit properly on the rim! You risk having it blow off while you ride. Improve the fit by building up the rim bed with tape, then seat the tire.
Pro Tip: For many riders, it makes sense to run inner tubes. First of all, it makes your bike faster: A thin, lightweight tube adds less resistance than liquid sealant sloshing around inside your tire. The tube reinforces the rim/tire joint, greatly reducing the risk of blow-offs. If you are concerned about flats, you can add sealant to your inner tube and obtain similar puncture protection with less hassle.
There is no doubt about it: Supple tires are less resistant to punctures – they don’t have the ultra-thick tread and reinforcing belts that resist punctures, but also make tires stiff, heavy and slow. If you get a lot of flats with your current tires – and your tires aren’t worn paper-thin – you probably shouldn’t run supple tires.
If you ride on the shoulders of busy highways, which are strewn with debris ranging from broken beer bottles to steel wires from exploded truck tires, you’ll have flats with most tires, and supple high-performance tires are definitely not a good choice. The photo above was taken during a 600 km Flèche ride. Between three bikes and one tandem, we had one puncture during the entire ride – during the 5 kilometers we rode on a highway shoulder.
Fortunately, as more riders have adopted wider tires, punctures have become a relatively rare occurrence. A 42 mm tire inflated to 35 psi (2.4 bar) will just roll over most debris that would puncture a narrower tire inflated to higher pressures. And since wider tires encourage you to explore backroads with cleaner pavement, the actual frequency of flats is much less than in the past, even though our tire casings, by themselves, are less puncture-resistant.
Pro Tip: Racers used to wipe their tires after riding through debris. If the debris is removed before it gets hammered into the tire, most flats can be avoided. Rather than risk injury by putting your hands on your tires, you can use tire wipers – little wires that brush debris off your tires.
Supple sidewalls are thinner and easier to cut. When the tire scrapes along a rock, especially a sharp one, the sidewall can get cut. How does often this happen? It depends. In some regions, the rocks are sharper than in others. Some riders let the bike move around under them more, so the tires aren’t forced into the rocks, reducing the risk of sidewall cuts. And sometimes, it is just plain bad luck.
I’ve ridden our Extralight tires over 10,000s of miles on rough gravel, and I’ve had one sidewall cut – in the epic Otaki 100 km Mountain Bike Race in Japan. It didn’t destroy the tire, as it cut only through one of the three layers of the casing. I rode the tire for another week on a tour, then replaced it.
Pro Tip: Our Standard casings use slightly thicker threads, making them more cut-resistant than the ultra-supple Extralight models.
It shouldn’t come as a surprise that supple tires are more expensive. They are made from more expensive materials. Their finer tolerances mean that they have to be made mostly by hand, by skilled labor. They are made in small batches. All that costs a little more.
Fortunately, wider tires last a lot longer, because they spread the wear over a greater rubber surface. Now that I am running 42 mm-wide tires, I find that my tires lasts about three times as long as the 28s I used to run. So even if my tires cost three times as much (and they don’t), the per-mile cost is the same.
Pro Tip: If you ride relatively few miles, your tires will deteriorate and crack before you wear them out. Keep your tires out of direct sunlight and away from refrigerators, freezers and heater blowers. Electric motors emit ozone, which destroys the rubber of your tires. Stored in a cool, dark and dry place, your tires will last (almost) forever.
In the past, supple tires were tubulars that only racers used, and only for races and special events. We all switched to our ‘training wheels’ for other rides, because the hassles and costs associated with tubulars were too great for everyday use.
Fortunately, supple tires are now available as clinchers. Wider tires have greatly improved the old problems of flat and wear resistance. We’ve made some additional tweaks to Compass / Rene Herse tires to make them more user-friendly without detracting from their performance. Our goal is to make you smile every time you go for a ride.