T47 TRAC Internal

TRAC stands for 'Twin Row Angular Contact', and this is exactly the type of bearing you'll find inside the shell of this T47 unit. Instead of a conventional, single row cartridge bearing, we decided to fit out our TRAC unit with bearing cartridges containing two rows of bearings, more evenly distributing the forces generated by the rider's weight, and when pedalling on rough surfaces. This system has huge benefits on bottom bracket longevity, and also increases pedalling efficiency by improving the overall stiffness of the crankset-bottom bracket interface.

The TRAC bottom bracket system comes ready for use with a 30mm crank axle, but it can be easily converted for use with other axle sizes. Seido offers adapter kits that enable the use of 29mm, 24mm and 24/ 22mm axle daimeter configurations. Finding spare bearings for the unit is also made much easier - they are also available at our webstore. No more headache from convoluted processes when trying to figure out bearing specs.

The T47 interface has many benefits, from allowing more space in the area to facilitate internal cable routing, to the greater ease of maintenance when compared to other BB standards.

This is the Internal version of the TRAC Bottom Bracket, suited to wider BB shells, from 85.5mm to 92.5mm. Click here to see the external version.  

In the Summer of 2025, we took a deep dive into the subject of T47 bottom brackets, with our dedicated T47 blog post. Take a look at the blog section of our webstore to check out some of our other articles and interviews too. 

COLOUR
Black

CUP MATERIAL
Aluminum

SPINDLE SIZE (mm)
30 mm

SUITABLE BB SHELL WIDTH (mm)
85.5 / 92.5 mm

TYPE
Internal

TOOL INTERFACE
T47 52-16 Tool

BEARINGS
3806, 30 x 42 x 10 mm

EXTRA INFO
Adaptable to 29, 24 and 24 / 22 mm with our TRAC spindle adapters

Twin Row Angular Contact Bearing

Includes 2 x 2 mm, 4 x 0.5 mm washer and 1 x wave washer

WEIGHT
130 g