How to Upgrade 21 Speed Bicycle to 24 Speed (Complete Shimano Conversion Guide)
OMO BikesShare
Many riders ask if they can upgrade their 21-gears bicycle to a 24-gears setup.
The answer is yes. However, upgrading to 24 speeds is more than simply replacing the gears. Since a 24-speed drivetrain uses an 8-speed cassette, several components must work together for smooth and reliable shifting.
Components Required
A typical 21-speed to 24-speed upgrade requires:
- 8-Speed Cassette
- 8-Speed Rear Derailleur
- 8-Speed Shifter
- 8-Speed Chain
- Front Derailleur (if required)
- Crank (optional)
- Freehub (only if your bicycle currently uses a 7-speed freewheel)
Complete Upgrade Kit (Recommended)
The easiest option is to purchase a complete Shimano 24-Speed Upgrade Kit, which includes all the major drivetrain components required for the conversion.
https://omobikes.com/products/shimano-24-gears-set-complete
Individual Components
Shifters
For V-Brake & Mechanical Disc Brake
https://omobikes.com/products/shimano-shifter-st-ef500-altus-shift-brake-lever
For Hydraulic Disc Brake
https://omobikes.com/products/shimano-shifter-m-315-altus-3x8speed
8-Speed Cassette
https://omobikes.com/products/shimano-cassette-hg-200-8s
Rear Derailleur
Shimano Acera RD-M3020
https://omobikes.com/products/rear-derailleur-shimano-rd-m3020-acera
Front Derailleur
Shimano Tourney FD-TY600
https://omobikes.com/products/shimano-fd-ty600-tourney-front-derailleur
Shimano Altus FD-M310
https://omobikes.com/products/bicycle-front-derailleur-shimano-fd-m310-altus
8-Speed Chain
KMC Z8 Chain
https://omobikes.com/products/kmc-z8-chain-for-8-gears-24-gears
Crank (Optional)
A crank upgrade is not required when converting from 21-speed to 24-speed. However, if your existing crankset is worn out or you want to upgrade its quality, you can replace it with:
https://omobikes.com/products/prowheel-crankset-for-21-gears-24-27-gears-mtb-hybrid-cycle
Do I Need a Freehub?
If your bicycle currently has a 7-speed freewheel, you will also need to convert to a cassette (freehub) before installing an 8-speed cassette.
Cassette Hub:
https://omobikes.com/products/buzzer-alloy-bicycle-hub-sealed-bearing-for-cassette
Need Help?
Not sure which parts your bicycle needs? Send us a photo of your bicycle or your existing drivetrain on WhatsApp, and we'll help you choose the correct components.