Mountain Bike Derailleurs

Shop front and rear mountain bike derailleurs from Decathlon with leading brands available including Shimano and Sram. Derailleurs provide tension and pull that allows you to change gears.
21 items
SHIMANO 7/8-Speed Rear Derailleur Acera M3020
SHIMANO 7/8-Speed Rear Derailleur Acera M3020
Rate: 4.3 stars, 3 votes
£27.99
SRAM X4 7- to 9-Speed Rear Derailleur
SRAM X4 7- to 9-Speed Rear Derailleur
Rate: 3.9 stars, 251 votes
£19.99
DECATHLON Triple Chainwheel Front Derailleur
DECATHLON Triple Chainwheel Front Derailleur
Rate: 4.3 stars, 387 votes
£14.99
DECATHLON 8 to 9 Speed Rear Derailleur
DECATHLON 8 to 9 Speed Rear Derailleur
Rate: 4.3 stars, 17 votes
£24.99
SHIMANO 9-Speed Rear Derailleur Alivio M3100
SHIMANO 9-Speed Rear Derailleur Alivio M3100
Rate: 4.5 stars, 61 votes
£31.49£42.99
SHIMANO Rear Derailleur 6/7-Speed Shimano Tourney TY300
SHIMANO Rear Derailleur 6/7-Speed Shimano Tourney TY300
Rate: 4.7 stars, 175 votes
£11.99
SHIMANO Shimano FD-R3000-B Sora Front Derailleur Clamp-On
SHIMANO Shimano FD-R3000-B Sora Front Derailleur Clamp-On
Sold and shipped by Sprocket and Gear Ltd
£34.74
SHIMANO Shimano Tiagra FD-4700-F Front Derailleur Braze On
SHIMANO Shimano Tiagra FD-4700-F Front Derailleur Braze On
Sold and shipped by Sprocket and Gear Ltd
£42.49
SHIMANO Shimano Acera 7/8 speed Rear derailleur RD-M360-SGS-L
SHIMANO Shimano Acera 7/8 speed Rear derailleur RD-M360-SGS-L
Sold and shipped by Sprocket and Gear Ltd
£33.49
CAMPAGNOLO Campagnolo Veloce Braze On Front Derailleur
CAMPAGNOLO Campagnolo Veloce Braze On Front Derailleur
Sold and shipped by Sprocket and Gear Ltd
£35.49
SHIMANO Shimano rear derailleur 9 speed Altus RD M2000 SGS
SHIMANO Shimano rear derailleur 9 speed Altus RD M2000 SGS
Sold and shipped by Sprocket and Gear Ltd
£35.98
BERTIN Front Derailleur Altus FD-M313-6 3x 7/8 Speed
BERTIN Front Derailleur Altus FD-M313-6 3x 7/8 Speed
Rate: 4.5 stars, 90 votes
£19.99
SHIMANO Shimano Tiagra FD-4700-BSM Front Derailleur 31.8mm
SHIMANO Shimano Tiagra FD-4700-BSM Front Derailleur 31.8mm
Sold and shipped by Sprocket and Gear Ltd
£36.98
SHIMANO Shimano Tiagra FD-4700-BL Front Derailleur 34.9mm
SHIMANO Shimano Tiagra FD-4700-BL Front Derailleur 34.9mm
Sold and shipped by Sprocket and Gear Ltd
£41.97
SRAM SRAM X5 Rear Derailleur 9 Speed - Medium Cage
SRAM SRAM X5 Rear Derailleur 9 Speed - Medium Cage
Sold and shipped by Sprocket and Gear Ltd
£50.84
SHIMANO Shimano Tourney RD-TZ500 Direct Mount 6 Speed
SHIMANO Shimano Tourney RD-TZ500 Direct Mount 6 Speed
Sold and shipped by Sprocket and Gear Ltd
£23.49
SHIMANO Shimano 105 FD-5801-BL Front Derailleur 2 x 11 Speed
SHIMANO Shimano 105 FD-5801-BL Front Derailleur 2 x 11 Speed
Sold and shipped by Sprocket and Gear Ltd
£35.44
SHIMANO Shimano Acera RD-M3020 7/8 Speed Rear Derailleur SGS Long Cage
SHIMANO Shimano Acera RD-M3020 7/8 Speed Rear Derailleur SGS Long Cage
Sold and shipped by Sprocket and Gear Ltd
£33.98
SHIMANO Shimano Sora RD-R3000 9 Speed Derailleur - GS / Medium Cage
SHIMANO Shimano Sora RD-R3000 9 Speed Derailleur - GS / Medium Cage
Sold and shipped by Sprocket and Gear Ltd
£44.49
SHIMANO Shimano FD-TZ500-DS6 Tourney Front Derailleur Clamp-On
SHIMANO Shimano FD-TZ500-DS6 Tourney Front Derailleur Clamp-On
Sold and shipped by Sprocket and Gear Ltd
£11.98
DECATHLON 3 to 6 Speed Rear Derailleur
DECATHLON 3 to 6 Speed Rear Derailleur
Rate: 4.2 stars, 501 votes
£14.99
4.3/5 based on 1485 reviews collected online and in stores

A MTB derailleur is the mechanism that causes gears to change by shifting the chain at the rear sprocket of the bike. The derailleur is attached to the bike via a derailleur hanger. A cable then connects the derailleur mechanism to the mountain bike’s gear shifter in order to allow you to control the gear changes.

It’s a good idea to keep your derailleur clean in order to prolong its lifespan. However, if it becomes damaged, a replacement will ensure you can keep changing gears smoothly and minimise the risk of your chain slipping or becoming damaged itself.

When looking for a new mountain bike derailleur, check the compatibility of the derailleur with the speed of your drivetrain.