Support standards - a few words of introduction

For a bicycle to move smoothly, cranks must be placed in the frame. It would also be a good idea to place bearings between them. Nothing could be simpler, right? No, it's not. The bicycle industry makes life difficult for itself and cyclists by creating countless standards for every possible part of the bicycle (and it's not a complex mechanism, after all). Bottom brackets are no exception. For decades, this remained relatively under control, though there were, of course, exceptions that could frustrate mechanics. However, the real explosion began a dozen or so years ago with the introduction of press-fit bottom brackets. Frame manufacturers began competing to create unique solutions, and components, willingly or unwillingly, followed suit. In this article, I'll describe only a small portion of the existing solutions. These are the bottom bracket standards most frequently used by repair shops in the last few years.

Threaded bottom bracket shell

A straightforward solution, dominant for many years. Due to parts availability and ease of maintenance, we use it on all our bikes . It allows you to screw in bearing cups and place an axle between them, to which the cranks are attached. For a long time, ring and conical races were used, and bottom brackets had to be counter-locked, similar to Shimano wheels. In the 1990s, machined bottom brackets began to appear, which simply need to be tightened to the correct torque. They require virtually no maintenance, and when worn, they are simply replaced. Many newer standards are also used with threaded shells, such as Octalink, ISIS, and HollowTech II. The latter belongs to the group of bottom brackets with external bearings. This solution allows for the use of an integrated axle with the crank and larger diameter bearings. This results in significantly greater stiffness, which, in 10-, 11-, and 12-speed drivetrains, is crucial for derailleur operation, not to mention other advantages. The price (besides cost) is the bearing's durability.

• BSA. British/English/ISO Standard. The most popular bottom bracket standard today. Right-hand thread on the left side, left-hand thread on the right. Used in both market bikes and budget sports bikes, and until recently in high-end carbon frames. Truly universal, although it is also available in two shell widths – 68 mm and 73 mm.
• Italian. Evil. Why? It's right-hand threaded on both sides, so the drive side spins out while riding. Despite this seemingly serious drawback, the Italians stubbornly used it until recently, even on premium carbon road bikes. 70 mm wide.
• French, same problem as above. Fortunately, it's been discontinued for years, but that can be problematic if you need to replace it. You can still find them in older Peugeots, and there are plenty of them on the used market. I had a bike like that, and I had to adjust the bottom bracket play every week. 70mm wide.

Press-fit bottom bracket standards

A press-fit bottom bracket has many advantages. It allows for the use of larger bearings, is lighter, and is stiffer. Contrary to appearances, it doesn't make frame production easier. A tight fit requires a much more stringent manufacturing process and tighter tolerances than a threaded shell. Installing and replacing it also requires much greater precision and special presses and punches. The types of press-fit bottom brackets are practically worthy of an encyclopedia.

BB30

Introduced in 2006 by Canondale but open to other brands, this standard places the bearings directly within the aluminum frame. The traditional 68mm width reduces weight, but stiffness is also improved over traditional designs. The bearings are typically secured with retaining rings, and the system suffers from similar issues as BB90, though it's not as common. Canondale currently uses updated, wider versions of this standard: BB30A and BB30-83 Ai.

BB90/BB95

The former is standard road bike, the latter is MTB. Trek's patented solution. Hated by users and mechanics alike due to its delicate construction. The bearings are mounted directly in the frame and are prone to seizing. Worse still, they often damage the bearing housings in the bottom bracket, requiring expensive repairs or... frame replacement. The only way to avoid this problem is to replace the bearings regularly and frequently. It rewards them with exceptional stiffness and low weight.

BB86/BB92

One of the most common standards. 86.5 mm wide for road bikes, 91.5 mm for MTB. The bearings are housed in plastic cups, which means tolerances aren't as stringent as with Trek's standard, and more importantly, there's no risk of bearing damage to the shell. We recommend it.

PF30

It's also very common. It was created in 2009 as a development of the BB30 concept, but more durable and easier to service. The bearings, housed in plastic cups, operate on the same principle as the BB86. It's well-known and well-liked. Specialized likes to refer to it as OSBB on its mountain bikes, which is amusing because the same name refers to a completely different road standard. Canondale, of course, introduced its own variation, the PF30 A and PF30-83 Ai. Insane.

BBRight

Cervelo's standard bottom bracket. Available in both DirectFit (bearings directly inserted into the frame) and PressFit (plastic or aluminum cups). Very similar in design to the PF30, the bottom bracket shell is 11 millimeters wider on the right side, allowing for the use of larger-diameter tubes and a stiffer rear triangle. It is worth noting that in the case of newer MTB frames, even wider BOOST versions are available.

This is not the end

Problems with seat wear, creaking, and tolerances meant that history repeated itself, and in 2015, the T47 was introduced. In practice, it's a threaded PF30, designed to take advantage of the system's large diameter and width. At the same time, traditional mounting eliminates the problems of press-fit bottom brackets. It seems great, but so far, bike manufacturers aren't keen on it. This can be related to the weight—up to 100g more compared to the PF30 (including frame adaptations). Furthermore, threading the frame for the PF30 definitely voids the warranty. There are many other, less popular bottom bracket standards on the market. LOOK and Colnago offer unique versions, and the BB386 EVO and BB392 EVO, which are variations of the PF30, are also worth mentioning.

Bottom Bracket Standards I Want to Forget

This article wouldn't be complete without a little bit of complaining. Some bottom brackets should have been discontinued the moment they were designed, yet they still appear. I'll mention two of the worst:

• PressFit, a design from the communist era. Found in older Romets. Due to the quality of the fit, it's not just pressed in, but inserted (or hammered in with a rubber mallet). It always has play, and countering it is a struggle. Today, manufactured rather far east, it remains the bane of mechanics due to the number of Romets still in use. There are no good solutions, no better substitutes; all that's left is weeping and gnashing of teeth.
• American/OPC Standard Very similar to the above, with larger cup diameters. Same problems as above, but found in older BMX bikes and, surprisingly, newer (and not just cheap) cruisers. There's no escape.

To this list I would of course add the Italian and French standard and any bolt-in bottom bracket with plastic cups.

Bottom bracket standards and the situation in the bicycle industry

What do you think about this? A multitude of very similar, yet completely incompatible solutions is standard for bicycles. Different bottom bracket types are only a fraction of the problem. Just think of seatposts, hub axles, and headsets ( here's a separate article on headset standards ). Most mechanics and shop owners are irritated by the introduction of new standards, as it means having to stock up on spare parts. The alternative is to order a bottom bracket as needed, but this firstly leads to customer dissatisfaction and additional costs, and secondly, it can be... impossible. Unfortunately, Polish distributors don't always rise to the occasion. We can only observe developments, and when purchasing a bike with a new or rare bottom bracket standard, buy a spare right away.