The T47 threaded bottom bracket is not simply a "threaded PF30"—it is a precision-engineered system whose core strengths lie in compatibility and user-friendliness. Available in multiple variants (T47-68, T47-86, T47-85.5, T47A-77) to suit different bicycle frames and brands, its threaded design cures the creaking woes of press-fit systems while introducing new trade-offs in weight and tool compatibility.
T47 Specs Explained: More Than Just a Number
The “47” in T47 refers to the 47 mm threaded inner diameter; the “T” stands for “Threaded.” The real complexity lies in the variants, each engineered for specific frame geometries and stiffness requirements.
| Variant |
Shell Width |
Notes |
| T47-68 |
68 mm |
Standard width |
| T47-86 |
86 mm |
Wide-shell frames |
| T47-85.5 |
85.5 mm |
Trek-specific, usually interchangeable with T47-86 |
| T47A-77 |
77 mm |
Asymmetric; mainly for Felt & Factor bikes |
Key insight: Always match the bottom-bracket shell width (in millimetres) listed in your frame’s manual—never rely on the “T47” label alone.
Performance & Trade-offs
Weight & Structure
A stock T47 bottom bracket weighs ~180 g, plus ~100 g for the aluminium sleeve bonded inside the frame—about 300 g total. BB86 (95 g) and PF30 (130 g) are lighter. Yet T47’s threaded shell delivers unrivalled stiffness and durability. Good news: MTOMSEE’s T47-86 unit trims mass to 104–110 g.
Installation & Tools
T47’s biggest win is easy installation—only a standard bottom-bracket wrench is needed. Some brands (Trek, Felt, Factor) adopt a 2 mm-thin external flange for tool engagement; the shallow interface raises the risk of stripping threads if the tool isn’t perfectly aligned. MTOMSEE offers dedicated wrenches for every T47 variant.
Performance on the Road
Friction losses are marginally higher than BSA (T47 uses 6806 bearings vs BSA’s 6805), but the difference is barely measurable. BSA edges ahead in stiffness thanks to its smaller, tighter tolerances. Press-fit systems like BB86 transmit power most efficiently because load paths flow directly into the frame.
How to Choose the Right T47 Bottom Bracket
The key is matching your frame’s exact spec. Consult your frame manual for three critical parameters:
- Bicycle Shell width – the decisive dimension.
- Thread spec – both drive- and non-drive sides (all T47 variants use M47×1.0).
- Special variants – e.g., T47-85.5 for Trek, T47A-77 for asymmetric shells.
| Spec |
Drive Side |
Non-Drive Side |
Shell Width (mm) |
Remarks |
| T47-68 |
M47×1.0 |
M47×1.0 |
68 |
Standard |
| T47-86 |
M47×1.0 |
M47×1.0 |
86 |
Wide frames |
| T47-85.5 |
M47×1.0 |
M47×1.0 |
85.5 |
Trek-specific, often swappable with T47-86 |
| T47A-77 |
M47×1.0 |
M47×1.0 |
77 |
Asymmetric; mainly Felt & Factor |
“In bicycle engineering there is no perfect solution—only the right compromise. T47 was born as a precise answer to the twin demands of reliability and user-friendliness.”
