What is a T47

The T47 is a new bottom bracket standard that is becoming very popular among custom frame builders and is gradually being adopted by larger frame manufacturers. It was developed by Chris King with the assistance of others to solve the problem of creaking bottom brackets, which should never have been a problem. Essentially T47 is a threaded version of PF30. Pressfit bottom brackets have such a bad reputation that someone in the wank department came up with the name "Threadfit T47" to make it sound more appealing.

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Advantages

 secure

Press fit systems can have problems with the interface between the frame bottom bracket shell and the bottom bracket cups. For metal frames, the tolerances of the bottom bracket shell should be precisely maintained using cutting tools after welding and fabrication. Using a reamer and a facing tool, a perfectly round and flat bottom bracket shell can be produced, which is essential for steel and aluminum frames. However, this is not possible with carbon frames because the bore diameter of the bottom bracket shell can no longer be precisely adjusted using a reamer and a face mill after the carbon has been inserted.

As a result, a poorly adjusted carbon bottom bracket shell cannot securely hold the bearing cups in the frame, causing them to move and cause noise. On the other hand, threaded connections have been around for over 2,000 years and are a proven system for securely fastening parts. BSA threaded bottom brackets have a set of threads as an integral part of the bottom bracket shell, allowing the bottom bracket shells to be screwed directly into the frame, preventing any type of movement. If the bearing cups don't move, there will be no creaking.

Adaptable

The T47 has the great advantage of being adaptable to different crank spindle diameters and frame widths. It can accommodate bearings compatible with cranks with 30mm spindle, 29mm DUB, 22/24mm GXP and 24mm Shimano crank spindles. Configurations with internal or external bearings are available. The press-in systems have developed significantly in recent years, so that the inner diameter of the shells is even 37 mm. However, these small diameter press-fit cups are not ideal for today's larger diameter cranks.

Because each cup screws into the frame independently of the other, T47 cups can be used on any bottom bracket shell from 68mm to 132mm wide. The width of the housing and the length of the crankshaft are the deciding factors in which T47 bottom bracket cups to use.

Stiff

The bottom bracket connection, which is made up of the seat tube, down tube and chainstays, plays a crucial role in the rigidity of a bicycle frame. Bottom bracket shells with smaller inner diameters, such as Other models, such as BB86, often require wider bottom bracket shells and thicker tubes to achieve the same level of rigidity as the PF30 (46mm) base platform, which can be achieved with smaller diameter tubes. With a T47 shell that starts at a 46mm inner diameter and has no width restrictions, frame builders have a large platform to design the bottom bracket area of ​​the frame as they see fit to achieve their frame's performance goals.

Dimensions make redesign easier

The bottom bracket shells of the T47 not only offer plenty of space for bulbous carbon tubes, but also have the same dimensions as a PressFit 30 shell. This means it would be easy for engineers to upgrade frame designs from Press-Fit 30 to T47. T47 is an open standard, meaning any frame and component manufacturer can adopt it without restrictions. This makes it very likely that T47 will be widely accepted.

disadvantages

Weight

One of the biggest problems for most cyclists is the weight of the bike. A typical T47 bottom bracket weighs around 180g. To use T47, the bike requires either aluminum inserts or a sleeve in the frame, which typically weighs around 100g. The sum of these two components weighs almost 300 g. In comparison, the BB86 weighs around 95g while the PF30 weighs around 130g.

toolmaking

Other sources have already discussed the tools required for assembling and dismantling bottom brackets. A particular type of T47 has a shell width of 86.5mm, similar to BB86, and therefore has thin flanges for the tool to grip into. However, using a 2mm wide tool is not enough as the risk of slipping or detachment is high. Trek, Felt and Factor have stated that they will use this particular variant of T47.

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Difference between T47 and BSA BB

The T47 Shimano setup has higher friction loss compared to the BSA Shimano setup, which is mainly due to the bearings used. The T47 setup uses the 6806 bearings while the BSA setup uses the 6805 bearings. The difference between these two camps is small, but still measurable.

In addition to low friction loss, rigidity is also a desirable property. The BSA-Shimano setup is stiffer because it is smaller and has more precise absolute manufacturing tolerances. However, a press-fit solution like the BB86 is a better option as it transfers some of the load directly into the frame.

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What is a T47 frame?

T47 is a standard 47mm x 1.0mm threaded cup used on Trek, Felt and Factor bikes. It is also commonly used in custom builds and is available in a variety of widths.
The ICAN Graro frame is a revolutionary product for gravel enthusiasts looking for versatility, durability and high performance. Graro is equipped with a T47 bottom bracket that combines the benefits of larger threaded bottom brackets with improved durability and easy maintenance. This makes it perfect for the challenges of gravel riding.

ICAN Graro frame