Go lighter. Ride faster. The lightweight performance model iruka X launches with external gears, 1 kg lighter than existing models.
Tokyo-based folding bicycle company iruka Inc. (Masaki Mark Kobayashi, Founder and President) has just launched iruka X, the brand’s first model equipped with an external gear system.
iruka is a transformer bicycle that changes its form into four modes to suit the scene. Since the brand’s debut in 2019, iruka has shipped two models—the iruka S with an internal 8-speed and sport specs, and the iruka C with an internal 5-speed and comfort specs—to 18 countries* , steadily growing a global community of Flippers (iruka owners).
*As of October 2026
The third model in the lineup, iruka X—its name derived from “External”—retains the original jackknife frame structure inspired by a sommelier knife, while adopting a 9-speed external drivetrain. Compared with existing models, it achieves more than 1 kg of weight reduction and delivers a sharper, more agile ride as a lightweight performance bike.
The internal gear hubs used in iruka S and iruka C feature a single external sprocket, with multiple gears housed inside the hub shell. They allow shifting even while stopped, minimize mechanical issues, and require almost no maintenance. However, due to the larger number of components, they are slightly heavier than external systems and have a marginally lower theoretical transmission efficiency.
By contrast, the external drivetrain adopted on iruka X shifts by moving the chain across multiple sprockets according to gear selection. Unlike internal gear hubs, it cannot be shifted while stationary, and the exposed mechanism requires regular maintenance to sustain performance. However, its simpler structure makes it lighter and more direct in converting pedaling power into forward motion.
The development of iruka X required two key technical breakthroughs:
The first was to develop a new rear frame compatible with external gearing without compromising iruka’s distinctive silhouette. To prevent interference between the chain and chainstay in low gears, we designed a new asymmetric rear frame for iruka X with the right chainstay offset 7 mm inward. We also recessed part of the chainstay facing the tire to maintain sufficient tire clearance.
The second challenge was to solve the problem of the chain coming off during folding. In iruka’s folding mechanism, the distance between the bottom bracket axle and rear hub axle becomes shorter when the rear wheel is folded, creating significant chain slack. In the existing models, iruka’s own chain tensioner takes up this slack. With external gearing, however, the derailleur has to take on this role. Many standard derailleurs do not have enough chain capacity, which can cause the chain to come off during folding. To solve this problem, iruka X uses a super-long-cage derailleur from LTWOO* , achieving both stable shifting and smooth folding.
*A globally growing component manufacturer based in Guangzhou, China, founded by former SRAM engineers, with Asahi Cycle serving as its distributor in Japan.
iruka Founder and President Masaki Mark Kobayashi comments:
“I have always been attracted to the lightness and efficiency of external gears, while at the same time deeply appreciating the elegance of internal gear systems. For a long time, I thought we would never produce an externally geared model, because I believed the interference between the chain and rear frame in low gears, as well as chain drop during folding, could not be solved.
However, the knowledge and insight of our engineering team, together with a few fortunate coincidences, allowed us to overcome these challenges and bring X into production.
To all the future Flippers who have been considering buying an iruka, I feel a little guilty that we have added another attractive option alongside S and C and made your choice even more difficult. Sorry!”
Price, key specs, and sales
Retail prices in major currencies
JPY 269,800
USD 1,999.00
EUR 1,999.00
Key specs
Gears: 9-speed external gears (F 56T / R 11–28T)
Brakes: Mechanical disc brakes
Wheel size: 18 inches (Tire width 1.25)
Frame material: 6061 aluminum
Color variations: Silver / Storm Gray / Black / Red / Blue — 5 colors
Folded size: L78 x W35 x H48 cm (Same as the existing models)
Weight: 11.0 kg (without pedals and accessories)
Sales
Delivery scheduled to begin in later November. Available for pre-order now at iruka dealers and our online store.
Launch campaign offer
To mark the launch of iruka X, we’re running the “Choose an iruka. Choose a gift.” campaign for all models. Purchase an iruka and choose one accessory of your choice as a free gift. Please see here for details.
Features of the iruka series
iruka changes its form into four modes to suit the scene, expanding mobility through its revolutionary folding mechanism with the touch of a hand, defined by the head-turning jackknife frame with its double-arched top tube and bold single-arm front fork.
Run Mode — It’s a breeze.
Think small wheels mean a slower ride? Hop on iruka, and you’ll know right away—it’s the exception. Experience incredible speed with the perfectly tuned gear ratio, the high-stiffness frame that turns every pedal stroke into pure power, and geometry that delivers stability at high speeds.
Wait Mode — Park smart.
When you fold iruka’s rear wheel, the front end of the rear fork supports it and it stands on its own. It shortens to about 1 meter, needing only half the parking space of a standard bike. Even in crowded urban areas, iruka makes finding a spot a breeze. That’s smart parking.
Walk Mode — Walk it. Roll it.
You might think, even compact folded bikes are a pain to carry. And you’d be right. Except with iruka. Its front and rear wheels fold parallel and coaxially, which allows you to roll iruka like a carry cart. So metro concourses, airport terminals, and office hallways are no problem. iruka can go wherever you go.
Sleep Mode — Never been more compact
iruka folds 30–40% smaller than typical folding bikes* . Its sleek and refined rectangular shape fits neatly into any space—whether it’s a car trunk, on a train, or beneath your desk. You can even store it upright.
*Compared with typical 20-inch folding bicycles.
About iruka Inc.
iruka Inc. is a folding bicycle company based in Tokyo. Founder and President Masaki Mark Kobayashi was one of the founding members of OPT Inc.* , one of Japan’s largest internet advertising companies.
*Later renamed Digital Holdings, Inc. The company was formerly listed on the Prime Market of the Tokyo Stock Exchange and became a subsidiary of Hakuhodo DY Group Holdings in 2026.
Mark served as Director and CFO at OPT. While working there, he bought a folding bicycle and began commuting by bike. That experience led him to become obsessed with the idea of creating the coolest folding bicycle in the world. In 2008, he left the company and founded iruka with no previous experience in the bicycle industry. For the full story behind the development of iruka, please see Overview | Story.