PressFit 30 bottom bracket standard embraced by the handbuilt community
Every year at NAHBS we scan the aisles looking for common trends as history has consistently demonstrated that what shows up here today often arrives in the mainstream a year or two later. This year's show has been different, however, in that the pervasive theme hasn't been a genre of bike or even a particular style but rather a new piece of technology.
Roughly ten or so builders at NAHBS (a substantial figure given the small community) included SRAM's new PressFit 30 bottom bracket systems into their designs. Since the bearings themselves are the same size and they're spaced identically to standard BB30, existing BB30 cranks can be used and the benefits are also the same relative to most conventional threaded setups: lighter weight, more heel clearance, better bearing durability, and slightly improved stiffness. However, the PressFit 30 standard delivers those without the intricate shell machining and extremely tight tolerances normally required.
PressFit 30 requires only a straight, concentric bore nominally 46mm in diameter with parallel-faced ends and that's all – meaning it's easier and cheaper to manufacture while also increasing the likelihood that the finished product will actually meet specifications. There are no interior grooves required for snap rings, the system's nylon cups are more tolerant of slight dimensional variations, and there's no metallic sleeve required so ultralight bare carbon shells can be used.
Moreover, depending on the frame material there's also less chance of creaking and the larger-diameter shell provides more flexibility for adjoining tube dimensions and positioning – and the builders that are already on board seem to absolutely love it.
"I think it's more about the simplicity of the manufacturing process," said Drew Guldalian of Engin Cycles. "Boring out a [standard] BB30 is not impossible but in my opinion an unrealistic task from a manufacturer's standpoint that needs to do something to make money. With the PressFit 30, they're using the same technology with the larger bearings and the same technology with the bearings living inside the frame but they're utilizing the nylon to their advantage where you have a more realistic tolerance.
"And that's what it came down to," he continued, "the dread of finishing a bicycle, putting it on the machine, starting to bore it, having a really odd way of using a go-no go gage, and then you're done and [maybe it's] going in the garbage. And you do the PressFit 30 and you face the outside, you check your bore diameter, and if you need to ream it, you ream it, but you're not reaming it to such an insane tolerance."
"It's a fundamentally simpler system to use," said SRAM's Ed Nasjleti. "Plus there's a smaller compound miter for your seat tube and your down tube joint and a bigger area to work with for your chain stay height so I think there are some other advantages with the larger outer diameter."
Nasjleti is realistic about whether PressFit 30 will eventually become the dominant bottom bracket standard across the industry, though, saying that framebuilders that use more traditionally sized tubing will likely never accept the system's disparate proportions. In addition, some bicycle companies we spoke with prefer the design advantages that wider systems such as Shimano's press-fit system and Trek's drop-in setup allow.
Still, PressFit 30's extraordinarily straightforward dimensional requirements will certainly make it appealing to the mainstream industry as it can offer both a performance and cost advantage in most cases – a clear win-win. And the fact that it's so prevalent here at NAHBS is further indication that we'll see much more of PressFit 30 in the future.
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