MTB Transmission Groups

Single chainring and wide-range cassette

The single chainring has become standard on modern mountain bikes: a single ring at the front, with a wide and narrow tooth design to keep the chain in place, paired with a twelve-speed cassette that has a largest cog with fifty teeth or more. The range of gears is equivalent to that of a double chainring, with no front derailleur or left shifter, which frees up the handlebars. Steering becomes simpler, the chain is less likely to drop during bumps, and the bike gets lighter. The number of teeth on the chainring then balances ease of climbing with speed on flat sections.

The drivetrain

The mountain bike drivetrain also comes in different forms:

• Derailleurs.
• Shifter.
• Cassettes and Chains.
• Cranksets.
• Chainrings.
• Cables and Housings.

All the drivetrain components are collected on the drivetrain page.

From Deore to XTR, from Eagle to Transmission

Shimano created the Deore XT in 1982, the first group designed for mountain biking, and then placed the XTR at the top of its range in the early nineties, aimed at competition. In between, Deore offers robustness and low maintenance, while SLX and XT lighten the setup and smooth the gear shifting. Over at Sram, the Eagle family, launched in 2016, popularised twelve-speed systems. In 2023, Sram Transmission groups have mounted the derailleur directly onto the rear axle, via the UDH interface of the frame: without a derailleur hanger, the setup absorbs shocks against rocks better and maintains its adjustment. This configuration requires a compatible frame.

Wear and compatibility: renewing the entire drivetrain

The chain, cassette, and chainring wear out together: an elongated chain wears down the teeth of the cogs, and a new chain on a worn cassette will skip under load. Replacing the entire drivetrain resets everything and allows for an upgrade. On the rear wheel side, check the freehub body: Microspline for Shimano, XD for Sram, each designed to accommodate a small ten-tooth cog. For the frame, the standard of the bottom bracket and the chainline, which is wider on Boost frames, determine the crankset to choose. Electric mountain bikes benefit from reinforced parts, like the Linkglide range from Shimano.

Good deals

Good deals can also be found in the good plans, promotions, clearance, sales, and Black Friday. The new arrivals showcase the latest collections, and items shipped in 24h are prepared and dispatched within 24 hours. The highlights of the year follow a stable order: Black Friday in late autumn, year-end holidays, winter sales, French Days in spring, followed by summer sales and back-to-school sales.

Frequently asked questions

Which Shimano range should I choose for my mountain bike?

For hiking and leisure, Deore provides reliability and low maintenance. SLX and XT are suitable for regular riders looking to save weight, while XTR is for competitors aiming to shed every gram.

Can you upgrade a mountain bike from eleven to twelve speeds?

Yes, provided you change the shifter, derailleur, cassette, and chain together, and check that the rear wheel can accommodate the new cassette. The crankset can often be retained if its chainring is compatible with a twelve-speed chain.

How many teeth for the front chainring of a mountain bike?

A thirty-tooth chainring is a good starting point for hiking and enduro, while thirty-two or thirty-four teeth are suited for fast cross-country riding racing. The smaller the chainring, the easier the climbs, but at the expense of speed.

How can I tell if my mountain bike chain is worn?

A wear indicator placed between the links measures elongation: beyond the indicated limit, it should be replaced before it damages the cassette. In mountain biking, mud and sand accelerate wear, leading to frequent checks.

Do the brakes need to be from the same brand as the group?

No, hydraulic brakes operate independently of the drivetrain. Pairing them only requires checking the compatibility of the lever clamps with the shifters, as some brands offer common mounts.