The cycling world is buzzing with excitement following the announcement of the new 13-speed SRAM RED XPLR groupset. Combining innovation and performance, this drivetrain marks a turning point in the world of gravel bikes and will soon be a major player in road cycling. More than just an addition to the existing lineup, the SRAM RED XPLR promises to redefine standards in terms of gear range and modularity. In this article, we explore why this new drivetrain is a stroke of genius and how it could transform your cycling experience.
A Significant Turning Point in Bicycle Transmissions.
At CYKL, we are convinced that the new SRAM RED XPLR system marks a significant turning point in bicycle drivetrains. While 13-speed drivetrains have been on the market for some time, with Rotor pioneering them and Campagnolo following with its Ekar groupset designed for gravel riding, SRAM's entry into this area is a complete game changer. The possible configurations with this type of drivetrain allow the majority of road cyclists and touring riders to finally do away with the front derailleur.
This article is not simply an opinion or a technical description of the new transmission, but an in-depth reflection on the evolution of bicycle transmissions, present and future.
As a reminder, the SRAM RED XPLR AXS drivetrain announced recently is the gravel version of the latest RED AXS road groupset, launched earlier this year. This new groupset further elevates the XPLR range, initially introduced in 2021, and designed as a bridge between SRAM's mountain bike and road bike lines. It brings the road and mountain bike worlds even closer together, offering unprecedented flexibility. Beyond the 13-speed cassette, the derailleur features the unique T-TYPE or full mount standard. (More details below.) For us, it's clear that the T-TYPE rear derailleur mounting system will eventually be deployed on all types of bikes in the coming years. It remains to be seen how other brands will react to this new standard.
At CYKL, we anticipated this evolution. All our bikes, including our road models, are compatible with this new groupset. Thanks to the adoption of the UDH standard and the development of T-TYPE technology, our bikes are compatible not only with all drivetrains on the market, but also with T-TYPE.
Unlike Shimano, which offers gravel-specific groupsets with its GRX range, SRAM offers unparalleled flexibility. Want a double chainring crankset? Look in the road bike catalog. Prefer the simplicity of a single chainring with a wide gear range? The mountain bike catalog has you covered. This flexible approach allows for numerous hybrid builds, combining components from different disciplines.
The new Red XPLR AXS simply adds a new dimension to all these possibilities, while remaining compatible with many existing products. We've taken the time to write this in-depth article to explain why this 13-speed drivetrain with a 10-46T cassette is a revolution for most road and gravel riding. You'll also discover why the double chainring is destined to disappear and why SRAM's standardization strategy is a stroke of genius.
Why does a 13-speed transmission with a 10-46T cassette meet most road and gravel riding needs?
To understand the principle of a transmission, it is essential to consider three key factors: the range of speeds, the spacing of speeds, and the size of the chainring.
The Amplitude of Velocities
The gear range, expressed as a percentage, indicates the range of available gears. It varies depending on the terrain: a flat region requires a small range, while a mountainous region requires a large one. This range is primarily determined by the cassette size. For example, on a 2x12 drivetrain with a 10-30T cassette, the range is 441%. In comparison, a 10-46T cassette offers a range of 460%, surpassing even double chainring setups. Here's an overview of the gear ranges of different cassettes:
- 10-44T Cassette: 440%
- 10-46T Cassette: 460%
- 10-50T Cassette: 500%
- 10-52T Cassette: 520%
Thus, a 10-46T cassette offers a greater range than a double chainring.
Speed Gap
To determine the gap, the amplitude is divided by the number of speeds. However, this gap is not uniform across the entire amplitude. The first five speeds have a larger gap than the last five.
In theory, a 2x12 drivetrain offers 24 combinations (2 chainrings x 12 sprockets), but in reality, the number of usable speeds is between 16 and 18, due to chain overlap and inefficient combinations caused by chain crossing. With a 13-speed drivetrain, the gear spacing is optimized, providing a smooth and continuous progression. For example, a 10-46T cassette with a range of 10, 11, 12, 13, 15, 17, 19, 21, 24, 28, 32, 38, 46 offers similar spacing to a double chainring, with the added benefit of reduced chain overlap.
The Size of the Tray
The chainring size should be chosen according to your muscle strength and desired top speed, while maintaining a pedaling cadence between 80 and 95 RPM. A larger chainring allows you to ride faster, but requires more effort, especially uphill. It is therefore crucial to choose a suitable chainring to maximize the efficiency of the intermediate gears, staying as much as possible in gears 11, 12, 13, and 15 on the cassette for optimal chain alignment.
Other Factors to Consider
A single chainring drivetrain is simpler to use, faster when shifting gears, more reliable thanks to fewer parts, and lighter. All these advantages make a 13-speed drivetrain with a 10-46T cassette an ideal setup for a wide range of uses, from all-road/endurance road bikes to XC or trail mountain bikes. With a wide variety of chainring sizes available from SRAM and other manufacturers, it's possible to optimally adapt the drivetrain to each rider.
Other Reasons for the Success of this Transmission
Two key elements of the new SRAM drivetrains deserve special attention: the UDH derailleur hanger and the T-TYPE or full mount derailleurs.
The UDH Derailleur Hanger
SRAM initiated one of the most significant evolutions in bicycle drivetrains with the Universal Downward (UDH) derailleur hanger. Even before the introduction of the SRAM RED XPLR gravel groupset, SRAM had already implemented a long-term strategy. The derailleur hanger, often overlooked, became a revolutionary component.
Traditionally, the derailleur hanger is a sacrificial part connecting the rear derailleur to the frame, designed to bend or break upon impact, thus protecting both the derailleur and the frame. For years, each frame had its own specific hanger, complicating replacements. In 2019, SRAM launched the Universal Derailleur Hanger (UDH) standard, unifying standards and simplifying replacements. The UDH, consisting of the hanger itself and the UDH bolt, is an open, license-free standard adopted by many brands. It is compatible with derailleurs from various manufacturers, such as Shimano, Campagnolo, and TRP.
This standardization not only facilitates replacements but also improves structural integrity and optimizes shifting. UDH thus paved the way for SRAM's new full-mount system.
T-TYPE or Full Mount Derailleurs
SRAM discovered that more than half of drivetrain problems were related to the derailleur hanger and traditional rear derailleur design. The T-TYPE drivetrain project aimed to eliminate these variations. By removing all adjustment screws, SRAM simplified installation and significantly reduced problems.
The UDH derailleur hanger is designed to absorb shocks by pivoting backward or sliding slightly to absorb an impact. If it pivots, it can be pushed forward without loosening the thru-axle. It also features a hooked lip to reposition the chain on the smallest cog of the cassette in the event of a chain derailment.
The derailleur and bracket design has been reworked for a coaxial connection to the frame, eliminating the B-screw and other adjustment screws. The upper pulley now rotates around the cassette with a constant gap, improving shifting performance. SRAM has also developed an inline cage with a curve for better tire clearance, ensuring the upper pulley remains aligned with the cassette.
Thanks to this design, SRAM was able to specify precisely the required range of motion, eliminating traditional limit screws. The rear derailleur has a contact point with the cassette to prevent derailment into the spokes, and an internal stop point to prevent the chain from falling between the cassette and the frame.
The new interface, directly connected to the thru-axle, makes the derailleur significantly more resistant to lateral and frontal impacts, transferring less energy from a crash directly to the frame. The integrated overload clutch allows the derailleur to retract in the event of a hard impact or when the axle is released. This innovative design works with all bike concepts, including split pivots, and frame clearance specifications are available for frame designers.