MTB Rear Derailleur
A MTB Rear Derailleur or Rear Mech is a part of the drivetrain used to move the chain on each sprocket of the cassette.
It can be sold as part of a complete MTB Groupset or separately.
The derailleur is fixed to the Frame via a derailleur hanger as it is the most exposed part on the bicycle. The derailleur hanger is used to prevent any damage to the frame if a force is applied by a fall or during transport.
The main parts on a rear mech are: a cage, 2 jockey wheels and a complex assembly of springs and other mechanical parts. A
MTB Gear Shifter is a must have to operate the derailleur.
There is only two manufacturers available on the market:
Shimano and
Sram, both available at Alltricks.com
Rear Derailleur Cage Length
MTB Rear Mechs come with different cage length: Short, Medium or Long. A derailleur with a longer cage can accommodate a larger gear range (range of cogs on the Cassette and / or difference between the front chainring sizes).
When replacing a Rear derailleur, we advise you to take the same cage length as your current model.
When you are building a bike from scratch, you will need to calculate the total capacity with the formula:
Total Capacity = (Number of teeth on the largest cassette sprocket - Number of teeth on the smallest cassette sprocket) + (Number of teeth on the biggest Chainring - Number of teeth on the smallest Chainring).
If you still have any doubt, do not hesitate to contact the helpful
Alltricks tech team who will be happy to guide you through the many Mountain Bike Rear Mechs available.