700×44 Corkscrew Climb: a new type of tire
“Not just another semi-slick.”
We don’t ‘innovate’ just to create something new. We have a lot of respect for pioneers who came before us, like the U.S. Army engineers who discovered suspension losses or the mid-century constructeurs who built the original gravel bikes at a time when most roads in the mountains were still unpaved. We also have a healthy degree of skepticism when faced with group think and innovations that don’t make sense. That’s why, until now, there hasn’t been a semi-slick gravel tire in the Rene Herse program. Simply put, the established way to make semi-slicks resulted in tires that were neither particularly fast, nor did they grip particularly well.
And yet there are situations where semi-slicks make sense. Our measurements have found that at very high power outputs—above 400 watts—the knobs of our dual-purpose knobbies squirm a little and lose some of their ultra-low rolling resistance. That’s why gravel racers have asked us for a tire that combines the speed of our slicks with the traction of our knobbies. Could we make a tire that combines the best of all worlds?
As with all our products, we started completely from scratch. We talked to Ted King, Brennan Wertz, the Mazda Gravel Team and other racers. What performance metrics do they wanted from their ‘dream’ semi-slick? We calculated, measured and tested. After more than 3 years of R&D, the result is our new 700C x 44 mm Corkscrew Climb.
The new tire is named after the biggest climb of the SBT GRVL gravel race in Steamboat Springs, Colorado (above). A few years ago, Ted King won there on our slicks, but the new Corkscrew Climb would be even better-suited to this ultra-fast course (and many similar ones).
What makes the Corkscrew Climb so fundamentally different? On conventional semi-slicks, the tread is split into distinctive slick and knobby regions. That creates awkward transitions as you lean the bike into a turn. The Corkscrew Climb seamlessly transitions from slick center to shoulder knobs. Here are the most important features of the new tire:
- Continuous center tread for optimum power transfer.
- File tread in the center for optimum braking (special request from our pros).
- First row of knobs anchored on the smooth center for maximum stiffness and traction.
- Large side knobs for traction during cornering and when the tire sinks into the surface. Large knobs also flex less and roll faster than smaller knobs.
- Round profile and gradual transitions—no cornering surprises.
- Noise cancelling for shoulder knobs—quieter than other tires with knobs.
- Lightweight: class-leading weight, like all RH tires (481g – 564g, depending on casing).
The innovative technology of the new Rene Herse Corkscrew Climb is protected by three new patent filings:
Patent 1: A semi-slick tire with gradual transitions from slick to knobby.
This prevents abrupt changes in tire behavior as the rider leans into a corner—a common issue with conventional semi-slick tires. The new Corkscrew Climb offers predictable cornering traction at all times, whether on asphalt or gravel.
Patent 2: Knobs anchored on a wide continuous line of tread.
The first row of side knobs is 3-sided, with the 4th side anchored on the center tread. That results in stiffer knobs with superior traction under high power. You’ll especially notice the anchored knobs when you climb or sprint out of the saddle and rock the bike from side to side. Less flex of the knobs also reduces rolling resistance.
Patent 3: Significantly greater radius of tread than of casing.
One of the biggest challenges in designing the Corkscrew Climb was to maintain three features that make our Rene Herse tires so fast, so comfortable, and so sure-footed in corners:
- thin, light and fast-rolling center tread
- a round tire profile for optimum cornering
- tall side knobs
If we just filled in the middle of our knobby tread pattern, the slick center tread would be thick, heavy and stiff. Why not just add side knobs to our slicks? Then we’d lose the round profile that makes Rene Herse tires corner so well.
The innovative solution is to make the radius of the tread significantly larger than the radius of the tire casing. This also improves cornering traction by putting more rubber on the road. Effectively, this 44 mm tire corners like a much-wider tire.
This new invention combines a thin and supple center tread with tall side knobs. At the same time, the Corkscrew Climb has a round profile. Despite the thin center thread, the side knobs of the Corkscrew Climb are taller than those of most other semi-slicks. When you’re riding in a straight line, they don’t touch the ground and won’t slow you down. When you need the knobs—when you lean into a turn or when your tire sinks into the surface—the tall knobs provide superb traction.
Of course, the center tread is still thick enough to offer the same long-term durability as our other Rene Herse tires. And the knobs themselves have flat tops for optimum surface contact. Everything about the new tire has been tested and optimized to the nth degree.
The Corkscrew Climb also features our noise-cancelling tread pattern technology: The shoulder knobs are slightly staggered, so the frequencies of one knob hitting the ground cancel those from other knobs. Compared to other gravel tires we’ve tested, the Corkscrew Climb is almost eerily quiet. Unless you are looking at your tires, the Corkscrews feel exactly like our slicks—until you need extra traction, and the side knobs come into play.
The new 700C x 44 mm Corkscrew Climbs are available with four casings. All versions are tubeless compatible. They work equally well with the ultra-light and ultra-fast Rene Herse TPU tubes (or any other tubes). Why four casings? The casing determines the performance and durability of your tire:
Standard
- Comfortable and fast
- Strong enough to survive considerable abuse
- Our most economical choice
- 517 g
- $ 82
Extralight
- Speed: among the world’s fastest tires
- Comfort: amazingly smooth ride
- Weight: among world’s lightest gravel tires (in comparable sizes)
- 481 g
- $ 96
Endurance
- The extra-fine casing threads of our Extralight, in a denser, stronger weave
- Protection layer against punctures and sidewall cuts
- Same speed as our ‘Standard’ with extra protection
- 552 g
- $ 96
Endurance Plus
- Thicker casing threads for even more strength
- Even stronger protection layer
- One of the world’s toughest gravel tires
- 564 g
- $ 104
Prototypes of the new Corkscrew Climb have already proven themselves in the UCI Gravel World Championships, The Rad Dirt (above) and adventures in the Cascade Mountains during thousands of miles of testing. We also gave a few sets to independent journalists for testing. One commented: “The grip is certainly there, and they roll well—quieter also than the Oracle Ridge tires I like so much.”
We don’t use the word ‘revolution’ lightly—try these tires yourself and tell us whether you notice a difference! All versions of the Corkscrew Climb will be available in mid-January.
Further Information:
Photo credits: Linda Guerrette (Photo 3); Taylor Chase (Photo 7)
