Standards & Compatibility: T47, UDH, T-Type
The Paratu CP and Iuhu CP frame standards: bottom bracket T47 thread-together; rear derailleur Universal Derailleur Hanger (UDH); headset 1.5 tapered (EC44/EC56); seatpost 34.9mm; rear axle 148mm Boost; chainline 52mm. Maximum chainring size: 38T with standard 170mm crank. Internal cable routing with rubber plugs — compatible with standard and eMTB cable diameters.
Standards & Compatibility: T47, UDH, T-Type
Understanding the modern frame standards used on Dirtlab bikes. What they mean, why we chose them, and what you need to know for parts compatibility.
T47 Bottom Bracket
T47 is a threaded bottom bracket standard that combines the wide shell diameter of PF30 (46mm) with the reliability of traditional threaded interfaces. It eliminates the creaking and tolerance issues that plagued press-fit systems.
T47 Specifications
| Shell Width | 68mm (road) / 73mm (MTB) |
| Shell ID | 47mm |
| Threading | M47x1.0 (right cup: left-hand thread) |
| Spindle Compatibility | 30mm, 29mm, 28.99mm, DUB (28.99mm) |
| Tool Required | T47 specific (e.g., Wheels Mfg, Enduro) |
Why T47: Threaded = no creaking. Large diameter = stiffer shell junction. Compatible with all major crank manufacturers (SRAM DUB, Shimano, Race Face, etc.).
UDH (Universal Derailleur Hanger)
UDH is SRAM's Universal Derailleur Hanger standard. Instead of proprietary, model-specific hangers that are expensive and hard to find, UDH uses a single standardised hanger across all compatible frames.
Key Benefits
- Universal replacement: One hanger fits all UDH frames. Available at any bike shop worldwide.
- Self-aligning: The hanger design includes alignment features, reducing the chance of shifting issues after a crash.
- SRAM Transmission ready: Required for T-Type wireless drivetrains.
- Backwards compatible: Works with all existing SRAM Eagle derailleurs (mechanical and AXS).
Dirtlab UDH Models
All current Dirtlab carbon frames (Paratu CP, Iuhu CP, Iuhu HL, Tutumaz XC FS) use UDH. Titanium frames are available in both UDH and traditional hanger versions.
SRAM T-Type (Transmission)
T-Type is SRAM's latest wireless drivetrain architecture. It requires a UDH frame and introduces a new mounting interface between derailleur and hanger.
T-Type Compatibility with CP Platform
| SRAM XX T-Type | Full compatible (UDH required) |
| SRAM X0 T-Type | Full compatible (UDH required) |
| SRAM GX T-Type | Full compatible (UDH required) |
| SRAM Eagle AXS (non T-Type) | Compatible via UDH adapter plate |
| SRAM Eagle mechanical | Compatible via UDH |
| Shimano (any) | Compatible via UDH with Shimano direct-mount adapter |