Reliable Chain Retention for 104mm BCD Cranks.
The Burgtec 104mm BCD Thick Thin Chainring is a durable replacement or 1x conversion ring for compatible four-bolt mountain bike cranks. Its alternating tooth profile helps hold the chain securely across rough ground, while the 7075-T6 aluminium construction keeps weight down.
Available in 30T, 32T, 34T and 36T sizes, it gives you a choice between easier climbing gears and a higher top end. This is the standard round chainring and should not be confused with Burgtec’s oval version.
Compatibility
- Fits compatible four-bolt 104mm BCD mountain bike cranks
- Designed for single-chainring 1x drivetrains
- Compatible with Shimano 12-speed Hyperglide chains
- Works best with a clutch-equipped rear derailleur
- Available in 30T, 32T, 34T and 36T
- Standard round chainring, not oval
- Chainring bolts are not included
Check the BCD, available frame clearance and required chainline before ordering. A crank using four chainring bolts is not necessarily 104mm BCD, so measure the crank or check the manufacturer’s specifications rather than relying on its appearance.
Choosing the Right Size
Choose 30T for easier climbing, 32T for balanced trail gearing, 34T for a higher top end or 36T for stronger riders and faster terrain. Check frame clearance before moving to a larger chainring.
Important 30T Installation Note
The 30T chainring uses threaded mounting holes and requires 8mm × 0.75mm × 8mm chainring bolts. Conventional chainring bolts and nuts may not provide sufficient clearance.
Thick Thin Tooth Profile
The alternating thick and thin teeth match the different spaces within the chain links. This provides better chain engagement than a conventional derailleur chainring and helps reduce the chance of dropping the chain on rough trails.
A clutch rear derailleur is still recommended. Correct chain length, chainline and drivetrain condition also affect chain retention, so the chainring cannot compensate for a badly worn chain or poorly aligned drivetrain.
7075-T6 Aluminium Construction
The chainring is machined from 7075-T6 aluminium for a useful balance of strength, durability and low weight. Its black finish works with most cranksets and bike builds.
For an e-bike, we recommend Burgtec’s steel 104mm BCD e-bike chainring instead. The steel version is designed to better handle the additional torque and mileage commonly produced by e-bike use.
Key Features
- Four-bolt 104mm BCD mounting pattern
- Thick Thin tooth profile improves chain retention
- Designed for 1x mountain bike drivetrains
- 7075-T6 aluminium construction
- 30T, 32T, 34T and 36T options
- Black finish
- Standard round profile
Our Thoughts
This is a good option for replacing a worn chainring or converting a compatible older 104mm BCD crank to a simpler 1x drivetrain. The main points to check are the mounting pattern, chainline and available frame clearance. Remember that the 30T version also requires its specific threaded bolts.
