Rear derailleur Black Friday : Di2, AXS discounts

The gears of your drivetrain to check first

Count the cogs on the cassette and note the number of teeth on the largest one: the derailleur manufacturer sets the maximum size it can handle. Then calculate the required capacity, which is the difference between the big and small chainrings plus the difference between the big and small cogs; it determines the cage length, whether short, medium, or long. Finally, check the mounting: a traditional derailleur is bolted to the frame's dropout, but Sram T-Type drivetrains mount directly onto a UDH standard frame. The detailed guide can be found on the permanent page of bike rear derailleurs.

Cable, Di2, or AXS: the control decides

A mechanical derailleur responds to the cable from a shifter of the same system: at Shimano, two derailleurs with the same number of speeds, one for road and the other for MTB, may have different pulls, and the CUES or GRX families follow their own compatibility rules. A Di2 derailleur from Shimano, such as the RD-R8150 Ultegra or the RD-RX815 GRX, only works with Di2 switches. A Sram AXS derailleur communicates wirelessly with its controller and carries its own battery, sometimes sold separately, as indicated by the labels "no battery".

Derailleur on sale: cage and generation first

The strikethrough price of a rear derailleur applies to a specific cage and generation; the product sheet indicates these, and it is on these that two sales are compared.

• The cage: the same model often comes in short, medium, or long versions; only the length suitable for your capacity is appropriate.
• The generation: at Sram, the suffixes D1 or D2 distinguish two versions of the same derailleur.
• The destination: the XPLR versions from Sram and GRX from Shimano target gravel, with cogs larger than those for road.
• What is included: battery, dropout, or screws depending on the references.

The parts to consider with the derailleur

Worn pulleys or an elongated chain can spoil the adjustment of a new derailleur: check out the derailleur pulleys in Black Friday and the chains in the sale. If you're changing your cog range, choose the cassettes in Black Friday at the same time. For an MTB, the MTB rear derailleurs in the sale will make your selection. The clearance sale and new products follow after Black Friday has passed.

Rear derailleur brands during Black Friday

Shimano covers every level, from the Tourney RD-TY200 and RD-TY300 with 6 and 7 speeds to the Deore XT M8100 with 12 speeds, including the CUES RD-U4000 and RD-U6000, the road models Sora, Tiagra, 105, Ultegra, and Dura-Ace, and the electronic Di2 versions.

Sram ranges from the X5 with 9 speeds to the Eagle S200 and S500 designed for a 52-tooth cog, with the Apex XPLR for gravel and wireless AXS derailleurs: Rival and Force XPLR, XX and GX T-Type for UDH frames.

Box Components offers its Box One and Box Two derailleurs in long or extra-long cage versions.

Sunrace features MTB derailleurs with medium cages, including the MS100 with 10 speeds, and road models ranging from 6 to 8 speeds.

Microshift rounds out the offering with the Advent RD-M619M with 9 speeds and derailleurs compatible with Shimano, for both road and MTB.

Frequently asked questions

When does the Black Friday sale for derailleurs start?

Its Friday is the one that follows Thanksgiving, during the period leading up to the holidays, but at Vélo-Store, the Black Friday discounts on rear derailleurs run throughout November, giving you time to calculate the capacity you need.

How can I tell if my derailleur has a short or long cage?

Measure the distance between the axles of the two pulleys, or check the reference engraved on the body: the suffixes SS, GS, or SGS at Shimano denote a short, medium, or long cage.

Does an 11-speed derailleur work with 10 speeds?

Not generally: the cable pull changes from family to family. Only certain combinations, published by the manufacturer, will work; rely on their compatibility charts.

Should I change the derailleur dropout at the same time?

If it is bent, yes: a new derailleur on a twisted dropout has difficulties shifting gears and may get caught in the wheel. The dropout is specific to each frame; take note of its reference before ordering.

Can I install a rear derailleur myself?

Yes, with an Allen key, cable cutting pliers, and a bit of method: mounting, chain length, cable tension, then limit screws and guard bolts. For an electronic model, pairing follows the manufacturer's instructions.