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Rear derailleur

The rear derailleur moves the chain across the rear cogs. A replacement must match your speed count, gear range and how it mounts to the frame.

Last edited Nov 8, 2026 by Pedalwise team Edit History Add a subpage

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The rear derailleur is the arm under the rear cogs that moves the chain from gear to gear and keeps it tight. It hangs low on the right side of the bike, so it's often what gets bent when an e-bike tips over.

What it's used for

Replace a derailleur that is bent, cracked or worn loose at its pivots, or that can't be adjusted to shift cleanly. Check the cheaper parts first: a bent derailleur hanger or a stretched shifter cable causes many of the same symptoms, and Adjust rear derailleur covers the setup.

What to look for

  • Same speed series. Competitive Cyclist advises keeping the cassette, chain, shifter and derailleur in the same speed series and brand, since shifting index and spacing differ between them (Competitive Cyclist drivetrain FAQ). Count your cogs and check your cassette or freewheel.
  • Capacity and largest cog. Add the difference between your largest and smallest chainrings to the difference between your largest and smallest cogs, and compare that with the derailleur's rated capacity. Also check its maximum cog size (Competitive Cyclist).
  • How it mounts. Check how yours attaches before ordering. Heybike notes that its 6 and 7 speed Shimano replacement is direct mount, not hub bolt mount, and sells it per model (Heybike rear derailleur). Shimano describes its direct mount option as a way to make rear wheels easier to remove and fit (Shimano direct mount).
  • Common e-bike units. Many budget e-bikes use 6 or 7 speed derailleurs. Ebike Supershop lists the Shimano Tourney RD-TY500, a 6 and 7 speed long cage derailleur for index shifting (Ebike Supershop).
  • Model specific parts. Where your maker sells its own version, buy that one. Heybike lists separate variants for the Cityrun, Ranger S, Mars, Brawn and other models (Heybike).
  • Hub motor wheels. On a rear hub motor bike, the wheel and motor cable may need to come out to do the job. See Rear hub wheel removal.

Typical price

  • Heybike lists its rear derailleur from $25.00 to $59.00 depending on the model, with several variants shown sold out (read Nov 9, 2026) (Heybike).
  • Ebike Supershop lists the Shimano Tourney RD-TY500 at $24.99 (read Nov 9, 2026) (Ebike Supershop).

Where to buy

  1. Your bike maker's parts store or support team, such as Heybike.
  2. A Shimano or SRAM dealer, usually your local bike shop.
  3. Independent specialists in Where to buy e-bike repair parts, such as Ebike Supershop.
  4. A local shop, through find a shop, which can also straighten a hanger and set up the new derailleur.

Videos

How to Adjust a Rear Derailleur: Limit Screws & Indexing from Park Tool: Sets the limit screws and tunes indexing with the barrel adjuster so the chain shifts cleanly across the cassette.

Guides that use it

Sources

Stuck after these checks? Find a shop near you.

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