Bottom Brackets



Bottom Brackets

The evolution of Bottom Brackets (BBs) has marched in step with that of the bicycle frame.

As different frame manufacturers sought ways to bring their visions to fruition, Full Speed Ahead has been there with BBs to fit their needs. We were pioneers with early square taper and ISIS systems with quad bearings. More recently we’ve pushed farther forward with MegaExo and the BB30 and PressFit30 standards. Our most recent revolution is the BB386EVO crank and BB system which has been widely recognised for its simplicity and universal fit. It is appreciated by frame builders and shop owners who instantly recognise that the one system works with most bikes. The system consists of cranksets that will fit a multitude of BBs up to 86mm wide, with the correct adaptor. For dealers this system reduces inventory yet services a greater variety of customer needs – just another example of FSA’s understanding of the market and ensuring they support dealers and, ultimately, consumers.


BB386EVO is based on the existing BB30 system. The revolution of the 30mm spindle opened the door for the most significant improvement in crank design in many years. BB30 raised the bar for crankset weight, stiffness, and design. The key is the 30mm diameter alloy spindle, formed in a high-pressure, low-speed extrusion process. The 30mm spindle improved torsional stiffness, while reducing the spindle, and increasing the contact area between the crank arm and the spindle. The BB386EVO design simply modifies the BB30 design to a wider width, and incorporates a press fit bearing cup, rather than the direct fit bearing of the BB30 system. This slight modification allows the adaptability of the design to other BB shells, and gives the frame builder more landscape to craft their frames.

The wider BB386EVO shell offers greatly increased surface area, up to a diameter of around 83mm, so the shape of the tubes can be further modified to achieve the ride performance frame designers want. A standard 68mm BB shell width allows a down tube or seat tube diameter of around 63mm maximum. The BB386EVO system allows a much more generous area, up to around 80-81mm. This solution can really increase frame stiffness and, using the press fit cups, allows the frame maker to eliminate any alloy insert into the BB shell, for a big weight reduction.

From the component makers perspective, the BB386EVO system allows the flexibility to fit many more frames. The BB386EVO uses the proven 30mm alloy spindle, which already is known to reduce weight and improve stiffness. Mating this to the wider BB shell, and press fit cups, allows this crankset to fit not only the 386EVO BB shell, but also to be adaptable to threaded frames, and to BB30 frames. The wider BB shell allows chain stays to be optimized, with either a greater thickness, or a wider spacing, to allow greater stiffness, plus better tire clearance, and a narrower BB shell.

The crankset is able to keep a normal Q-factor, while being adaptable to three different bottom bracket systems. FSA will offer BB adapters that will allow this crankset to have the widest range of adaptability of any crankset we produce. Thus, the BB386EVO crankset can eliminate the need to offer different crankset models for the different BB standards. FSA will be able to offer one crankset that will fit all three, and still be lighter and stiff than our current MegaExo option.

‘One for all, all for one’. The BB386EVO is all about adaptability. The BB386EVO Crank will fit multiple frame BB standards and the BB386EVO BB design allows the use of crank sets with the ؘ24mm integrated spindle by simple bearing adapters which reduce the ؘ30mm bearings to fit the ؘ24mm spindle, in addition to our BB386EVO crank.

FSA will also offer simple bottom brackets and adapters to allow one crank set to fit all three types of frames, thus simplifying both the sales and assembly process, and eliminating the need for retailers to stock three different types of crank sets to service their customers. The BB386EVO crankset will not only fit all of these bottom bracket types, but will also offer greatly improved performance compared to ؘ24mm integrated systems, and reduced weight. One crank can do it all.

BB386EVO is already in by several brands, and we expect more adopters to take advantage of this design.

The use of the press fit bearing cups allows the frame designer to eliminate any alloy or steel component inside the BB shell area, since the nylon composite cups have a greater range of fit tolerance. Therefore, the BB shell area can become lighter, and simpler to make.

There have always been many standards of BB in the market. Those of us old enough will remember French threading, Swiss threading, as well as English and Italian. The Bike market follows trends that continue innovation. As opportunities arise to really improve performance, or adaptability, we believe the industry will adopt them, provided they make sense. Thanks to this new standard, cross platform adaptability, lighter weight, and increased BB surface area can now be had with one system.

BB386EVO is more adaptable to a wider range of bike frames. It lowers the weight and improves the stiffness over 24mm diameter integrated crank sets and allows bike frame designers more room to optimize their performance.

In time, it’s possible that we will see the BB386EVO system also on CycloCross and MTB frames, since the benefits – weight reduction, stiffness increase and better clearance between the chain stays – make sense here also. However, wider width designs that use large shell OD (like BB386EVO) will have to be concerned with chain ring interference issues with triple MTB cranks.