Road transmission groups

What a complete group contains

A group brings together the parts that transfer power and those that slow down the bike: shifters, front and rear derailleurs, crankset, bottom bracket, cassette, chain, and brake calipers. All are designed for the same number of gears, from eight to twelve depending on the range, and for the same spacing between sprockets. This consistency ensures precise gear changes: a twelve-speed chain, which is narrower, does not have the same width as an eleven-speed chain. Before buying, check the freehub body of the rear wheel, which must accommodate the chosen cassette, and the frame's bottom bracket standard.

The transmission

The road transmission also comes in different types:

• Derailleurs.
• Derailleur shifter.
• Cranksets.
• Cassettes and Chains.
• Chainrings.
• Cables and Housing.

All transmission items are gathered on the transmission page.

Shimano, Sram, Campagnolo: the range hierarchy

Shimano, founded in 1921 in Sakai, Japan, organizes its road range from Claris and Sora, entry-level groups, up to Ultegra and Dura-Ace, launched in 1973 for competition. Sram, started in Chicago in 1987, offers Apex, Rival, Force, and Red, and introduced in 2015 the first wireless road transmission, now marketed under the name AXS. Campagnolo, founded in Vicenza in 1933 by Tullio Campagnolo, the inventor of the quick release, focuses on high-end products and a finish favoured by purists. Upgrading generally results in weight savings and finer adjustments; reliability is already high in mid-range groups.

Pads or discs, cables or electronics

The choice of brakes depends on the frame: a bike designed for rim brakes cannot accept disc calipers without dedicated mounting points, and vice versa. The hydraulic disc brake stops strongly and consistently in the rain, whereas the pad brake remains lighter and easier to adjust. The lever also comes in two types: mechanical, with replaceable cables, or electronic, with motors that shift gears with a simple press and maintain constant adjustment, but require a rechargeable battery. At Shimano, the battery is central, housed in the frame or seat post; at Sram, each derailleur has its own.

Good deals

Great deals can also be found in good deals, promotions, clearance, sales, Black Friday. The new arrivals showcase the latest collections, and items shipped within 24 hours are prepared and dispatched in 24 hours. The key events of the year follow a stable order: Black Friday at the end of autumn, the holiday season, the winter sales, the French Days in spring, then the summer sales and back-to-school period.

Frequently asked questions

Can you mix Shimano and Sram parts on a road bike?

This is not recommended: the cable pull ratios, sprocket spacing, and cassette standards differ from one brand to another. Only a few parts, like the chain or crankset, sometimes cross over, given the same number of speeds.

How long does a road bike transmission last?

The chain wears out first: its elongation is checked with a dedicated tool, about every two to three thousand kilometres. If replaced in time, it preserves the cassette and chainrings, which can then last through several chains.

What group should you choose for a first road bike?

An entry-level or mid-range group is more than enough to discover the road and ride regularly. Upgrading to a higher group is then justified by the search for lightweight, precision, and tighter gear ratios.

What is the battery life for an electronic group?

Depending on the system and usage, a charge covers several hundred to over a thousand kilometres. A light indicator or an app informs you of the remaining level: recharge before a long ride to avoid being stuck on a sprocket.

Why have groups gained speeds?

Adding sprockets expands the development range while keeping tight gaps between two gear ratios. This allows for tackling steep climbs without sacrificing speed on flat roads, resulting in smoother shifts.