FSA – Full Speed Ahead, if you want to be formal about it – have developed a new crank, bottom bracket and frame system that they reckon will become the standard for high-end frame and drivetrain component design.
We know what you’re thinking: another new system. Great, because the world is crying out for just one more.
Thankfully, the new BB386EVO system works with most (but not all) current bottom bracket standards and could actually make things easier. Maybe. Here’s hoping, anyway.
Okay, so if by any remote chance you’re confused by the current state of affairs, here’s where we’re currently at with bottom brackets.
Chances are, the bottom bracket shell on your road bike is 68mm wide.
There’s a good chance that if you’ve bought your bike in the last few years, you have a bottom bracket that is screwed into the frame with the cups sitting externally – such as an FSA MegaExo system. If so, the distance from the outside of one cup to the outside of the other will be 86.5mm, and the diameter of the cromo axle is 24mm.
But, on the other hand, you could have a BB30 (road BB30) or a PF30 bottom bracket where the bearings sit inside the bottom bracket shell (which is still 68mm wide). The 30 bit of the name refers to the diameter of the aluminium axle – 30mm – which is designed to be lighter and stiffer than standard.
Or you could have a BBright system, which is different again, or a BB86 setup…
Anyway, the new BB386EVO system is press fit and uses an 86.5mm bottom bracket shell width – the frame is wider down there than currently and the axle is as long as that of an external system. And the axle diameter is 30mm – the same as BB30.
Clear? Okay, so what are the advantages? According to FSA:
• The BB386EVO axle, 30mm in diameter, has a higher stiffness-to-weight ratio than the 24mm axle of a system like MegaExo.
• The bearings are positioned further apart than with BB30 for increased stiffness and stability.
• The BB386EVO crank arms are straighter than those you get with BB30, making for more rigidity.
The other major factor in its favour is that the BB386EVO crank system is compatible with threaded bottom bracket shells. In other words, although it’s essentially a press fit system, you can get a BB386EVO bottom bracket that’ll fit a threaded 68mm BB shell, so you can use new standard cranks on an old standard frame.
The BB386EVO system, although developed by FSA, is an open system, meaning that other manufacturers are free to produce their own frames, bottom brackets and cranks to the same specifications.
FSA are introducing four BB386EVO chainsets to begin with: K-Force Light models in both standard and compact, and the same for SL-K. They all have hollow carbon arms and in 170, 172.5 and 175mm options.
FSA have just sent us a new document explaining the whole thing in detail. Here it is in full. You might need a coffee and a couple of biscuits to keep you going:The idea of BB386EVO is based on the ground breaking BB30 system, developed by Cannondale. 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 [chainset – Ed] 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 weight to a minimum, 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 idea began with a request from two FSA customers, Wilier and BH. Both were working on a wider version of BB30, but their designs had different BB box lengths (Wilier's was 86mm and BH's was 80mm). Both ideas were interesting to FSA, but Wilier's 86mm design allowed FSA to make one crankset that could be also used on traditional 68mm threaded BB shells, thanks to the threaded reducer cups for 30mm spindles. Wilier and BH agreed to FSA's suggestion to both use the Wilier design and they proceeded to develop new frames based on this concept while FSA created the crankset. This collaborative alliance created the BB386EVO. From the perspective of a frame maker, BB386EVO allows the designer significantly more area to modify the performance characteristics of the frame. 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 amount of area, up to around 83mm. 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 maker's perspective, the BB386EVO system allows more flexibility of fit to more different 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 crankset is able to keep normal Q-factor [the distance between your pedals – Ed] , but be adaptable to three different bottom bracket systems. FSA will offer BB adapters hat 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 multiple different crank set 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. This is probably a question for the frame designers, but maximizing the surface area where the main frame members join, the bottom bracket area, allows more shaping that can improve stiffness, or other ride characteristics. Since the bearing width is increased with the shell width, the stance of the bearings relative to the crank arms remains relatively unchanged. The press fit 30 cups also eliminate the need for any alloy component in the shell, so weight is reduced as well. The wider BB386EVO shell allows a much greater surface area, up to around 80-81mm of diameter, so the shape of the tubes can be modified more to achieve the ride performance they want. Additionally, other frame components can also benefit. The wider BB shell allows chainstays 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. One important characteristic of the BB386EVO design is that it allows a wide range of adaptability both for the crankset to fit other frame standards, and for the frame to fit other crank standards. The BB386EVO frame design allows the use of crank sets with the 24mm integrated spindle by a number of simple bearing adapters which reduce the 30mm bearings to fit the 24mm spindle. Conversely, the BB386EVO crank set is widely adaptable to both threaded shells, and BB30 frames. 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 use by Wilier and BH. ABG (Litespeed) is moving ahead, and we expect other brands 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, bike brands can have many advantages for their frame designs. BB386EVO is more adaptable to a wider range of bike frames, while lowering the weight and improving the stiffness over 24mm diameter integrated cranksets, and allows bike frame designers more room to optimize their performance. It is possible that we will see this BB386EVO also on Cyclo Cross and MTB frames, since the benefits – weight reduction, stiffness increase and better clearance between the chainstays – make sense here also. But, wider width designs that use large shell OD, like BB386EVO will have to be concerned with chainring interference issues with triple MTB cranks.
Mat has worked for more bike magazines than anyone else in the known universe, dating back to a time when this was all just fields. He's been road.cc technical editor for four years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. When he's not cycling around Wiltshire, he's running around it, or possibly swimming (sadly, he's one of those 'triathletes'). Mat is a youthful 42-year-old Cambridge graduate, GSOH etc.