Oval Gearing for Compatible Shimano Direct-Mount Cranks.
The Burgtec Shimano Direct Mount Oval Alloy Thick Thin Chainring is designed for riders who prefer the feel of an oval ring on steep climbs and technical trails. Its oval profile changes the effective gearing through the pedal stroke, while Burgtec’s Thick Thin tooth pattern helps keep the chain securely engaged over rough ground.
Fully CNC-machined from 7075 aluminium, it is available in 30T and 32T sizes with a 3mm offset. It fits compatible Shimano M6100, M7100, M8100 and M9100 direct-mount mountain bike cranksets.
Compatibility
- Shimano MTB direct-mount interface
- Compatible with suitable Shimano Deore M6100 cranks
- Compatible with suitable Shimano SLX M7100 cranks
- Compatible with suitable Shimano Deore XT M8100 cranks
- Compatible with suitable Shimano XTR M9100 cranks
- Suitable for compatible 10, 11 and 12-speed drivetrains
- Designed for single-chainring mountain bike drivetrains
- 3mm chainring offset
Shimano has used several different chainring mounting systems. Check the model number and interface on your crank before ordering rather than relying on the drivetrain name alone.
How the Oval Profile Works
The chainring’s oval shape changes the effective gearing as the cranks rotate. It feels larger through the stronger part of the pedal stroke and smaller as the cranks pass through the upper and lower dead spots.
This does not create additional power, but some riders find that it helps them maintain a smoother cadence and better traction on steep or loose climbs. Other riders prefer the consistent feel of a conventional round chainring, so the choice ultimately comes down to riding style and personal preference.
Choose the Right Size
- 30T: Varies between an effective gearing of approximately 28T through the dead spot and 32T through the stronger part of the stroke
- 32T: Varies between an effective gearing of approximately 30T through the dead spot and 34T through the stronger part of the stroke
Burgtec recommends choosing the same stated tooth count as your current round chainring. A rider currently using a 30T round ring would normally start with the 30T oval version.
Check frame clearance, chain length and drivetrain adjustment if you change tooth count. The 32T option may require more clearance than the 30T version.
Thick Thin Tooth Profile
The alternating Thick Thin teeth match the inner and outer links of the chain, helping guide the chain onto the ring and improve retention over rough trails.
Mud Bleed shaping provides space for dirt and debris to clear from around the chain. The best results still depend on a compatible chain, correct chainline and a properly functioning clutch derailleur.
CNC-Machined 7075 Aluminium
The chainring is fully CNC-machined from 7075 aluminium, providing a useful balance of strength, stiffness and low weight. It is well suited to trail, enduro and cross-country bikes where dependable chain retention matters without adding unnecessary weight.
For regular full-power e-bike use, a dedicated steel e-bike chainring may provide better long-term resistance to drivetrain wear.
Key Features
- Oval chainring for compatible Shimano direct-mount cranks
- Available in 30T and 32T sizes
- Approximately 115% oval profile
- 3mm offset
- Fully CNC-machined from 7075 aluminium
- Thick Thin tooth profile supports chain retention
- Mud Bleed shaping helps clear dirt and debris
- Compatible with suitable 10, 11 and 12-speed drivetrains
- Burgtec Black finish
Our Thoughts
This is a good option for riders who like the smoother feeling of an oval ring when climbing steep or technical trails. We would normally match the stated size of the round chainring already fitted rather than changing the gearing at the same time.
Compatibility is the main thing to check. Confirm that your crank uses Shimano’s current MTB direct-mount interface and check the chain for wear before installing the new ring.
Why Buy from Chain Reaction?
- Help confirming crank and chainring compatibility
- Advice on choosing between 30T and 32T
- Professional chainring installation available
- Chain-wear and drivetrain-condition checks
- Independent Christchurch bike shop
- Nationwide New Zealand delivery
Specifications
- Brand: Burgtec
- Product type: Oval mountain bike chainring
- Material: CNC-machined 7075 aluminium
- Mount: Shimano MTB direct mount
- Available sizes: 30T and 32T
- Offset: 3mm
- Ovality: Approximately 115%
- Drivetrain compatibility: Suitable 10, 11 and 12-speed systems
- Tooth profile: Thick Thin with Mud Bleed
- Colour: Burgtec Black
- Intended use: Cross-country, trail and enduro mountain biking
