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This page explains what governing bodies, standards bodies and road authorities publish. It is not a substitute for cycle training from a qualified instructor, for a qualified bike mechanic, or for medical advice.
What a groupset is
A groupset is the collection of drivetrain and braking parts on a bike: the shifters, front and rear derailleurs, crankset and chainrings, cassette, chain and brakes. A few terms recur:
- 1x and 2x
- A "1x" drivetrain has a single chainring at the front and a "2x" drivetrain has two. Wikipedia says both are common on gravel bikes.
- Di2
- Shimano's name for its electronic shifting, as BikeRadar explains.
- AXS
- SRAM's name for its wireless electronic component system.
- Cassette range
- Written as the smallest and largest sprocket, such as 10-28, meaning 10 teeth on the smallest and 28 on the largest.
Three makers' electronic road groupsets
Shimano, SRAM and Campagnolo are the road groupset makers whose electronic groupsets are reported below. Their own figures are labelled as their claims. We could not open Shimano's own pages, so its details come from BikeRadar's review.
| Groupset | What is reported | Source |
|---|---|---|
| Shimano Dura-Ace Di2 R9200 | Launched in August 2021, adding a 12th rear sprocket and a semi-wireless design to the earlier R9170. The shifters talk to the rear derailleur wirelessly, while the derailleurs are still wired to a battery inside the frame. Shimano claims shifting 45 percent faster at the front and 58 percent faster at the rear than its predecessor; BikeRadar said the rear gain was hard to confirm on the bike | BikeRadar (4 January 2023) |
| SRAM RED AXS | Described by SRAM as fully wireless. SRAM claims it is the lightest electronic groupset available, about 150 grams lighter than the previous generation. The rear derailleur is listed as working with cassettes from 10-28 to 10-36, so with a 10-tooth smallest sprocket | SRAM product page (read 22 October 2026) |
| Campagnolo Super Record 13 | A wireless electronic road groupset with two chainrings and 13 sprockets, billed as the first of its kind, with four cassette options from 10-29 to 11-36. Campagnolo claims it is the lightest electronic disc-brake road groupset, at 2,435 g without a power meter. BikeRadar reported plans for 1x road, 1x time trial, 2x endurance and gravel versions, and a 1x gravel version called Super Record X from September 2025 | BikeRadar (4 June 2025) |
The makers' wider ranges could not be confirmed from the makers themselves, so they are not listed here.
What the UCI allows
As reproduced in the Japan Cycling Federation's copy of the UCI clarification guide (uploaded March 2026; edition date unconfirmed):
- Electronic shifting. Electronic derailleurs are authorised provided only the rider controls them, and combined brake and gear controls are allowed (Article 1.3.022 and commentary).
- Chainrings. Oval chainrings are allowed provided the path of the pedals stays circular (commentary on Article 1.3.010). The bike must be driven only by the legs, through a chainset, in a circular movement.
- One chain. The guide says only one chain may be used (commentary on Article 1.3.007).
- Track. Freewheels and multiple gears are not permitted on the track; the transmission is one chain, one chainring and one sprocket (Article 1.3.025).
- Road and cyclo-cross. A fixed gear is prohibited (commentary on Article 1.3.009).
- Data. Onboard devices may record mechanical data including power, cadence and gearing (Article 1.3.006 bis, introduced 10 June 2021).
The gear-ratio cap that is not in force
The UCI announced a test of a maximum gear of 54 x 11, which it described as 10.46 metres travelled per crank revolution, for a stage race in the second half of the 2025 season. BikeRadar (1 January 2026) reported that the cap would have ruled out the 10-tooth smallest sprockets used by SRAM and Campagnolo, and that SRAM brought a complaint to the Belgian Competition Authority.
The test was suspended after the Belgian Competition Authority's decision of 9 October 2025. Following its meeting of 2 to 4 June 2026, the UCI said the Brussels Court of Appeal had dismissed its appeal, that the protocol stays suspended, and that it will appeal to the Belgian Court of Cassation. No UCI gear-ratio limit applies now. The full story is on the 2026 changes page.
Who looks after the drivetrain
Installing, indexing and servicing a groupset is work for a qualified bike mechanic, and this site gives no procedures. The UCI's guide also says modifying competition equipment away from what the maker supplied is prohibited without prior UCI approval. See mechanics and bike fitting.
Sources
- BikeRadar, Shimano Dura-Ace Di2 R9200 review (Simon von Bromley, 4 January 2023)
- SRAM, RED AXS product page (maker claims, read 22 October 2026)
- BikeRadar, Campagnolo Super Record 13 (4 June 2025)
- Wikipedia, Gravel bicycle (secondary)
- UCI, Clarification Guide of the UCI Technical Regulation, Articles 1.3.001 to 1.3.034 (bilingual copy hosted by the Japan Cycling Federation, uploaded March 2026; edition date unverified)
- UCI, statement on its recent decisions regarding changes to equipment (undated)
- UCI, Management Committee meeting (2 to 4 June 2026)
- BikeRadar, the UCI rule changes for 2026 (1 January 2026)