- The T47 bottom bracket comes in three different iterations to accommodate different crank spindles. The bottom bracket pictured accommodates 24mm spindles and threads into the frame using the pink installation tool. Photo: Dan Cavallari | VeloNews
- The 30mm version of the T47 bottom bracket uses a different installation tool. A Campagnolo-compatible bottom bracket is in development. Photo: Dan Cavallari | VeloNews
- The T47 bottom brackets use a larger thread pitch than older thread-in bottom bracket versions. Photo: John Watson
- Argonaut's new road bike will be the first to feature Chris King's new T47 bottom bracket. Photo: John Watson
- A metal sleeve is bonded within the bottom bracket shell of this carbon frame. While it's one more part that needs to be integrated into the bottom bracket system, the tolerances are more lax and therefore less likely to be creaky. Photo: Dan Cavallari | VeloNews
- The 24mm version of the T47 is threaded into the bottom bracket shell quickly and easily using the bottom bracket installation tool. Photo: Dan Cavallari | VeloNews
- Metal frames that currently have a non-threaded PF30 shell can be tapped to accommodate the T47. Carbon frames, however, cannot be tapped for backward compatibility. Photo: Dan Cavallari | VeloNews
GUERNEVILLE, California (VN) — Ben Farver, founder of Argonaut Cycles, wants to make the perfect road bike. Problem is, with imperfect technology standards like PF30, that pursuit is impossible. So he, along with Chris King components, set about creating an alternative to PF30.
Yeah, my eyes were rolling when I heard the news too. Another bottom bracket? Unless it threads into the BB shell, I didn’t want to hear about it.
Well, I was in luck.
So let’s start with that skepticism: First off, it’s not a standard, because that word implies some sort of consistency across brands and platforms. There hasn’t been much of that in the last several years since a slew of press-in bottom brackets hit the market, each iteration as flawed as the next. Let’s call it a re-imagining, because this new iteration is something we’ve seen before, something we know works.
It’s called T47, and it’s a thread-in solution to PF30. Yes, threads. As in, it screws into the frame just like English bottom brackets we knew and loved.
What exactly does this mean for you, the rider? Think of the benefits of PF30: bigger bearings for longer life, larger bottom bracket shells for improved lateral stiffness, and a larger area that accommodates an array of tube shapes to tailor ride quality. Now take away the disadvantages of the system: the minuscule tolerances that need to be just right in order to get a creak-free interface, a perfectly straight installation to avoid damaging the BB shell, and all the tools needed to get the bearings in and out, again without damaging the frame.
That’s T47, a bottom bracket with big bearings that thread in easily to the bottom bracket shell. And once I rolled my eyes back into place, it occurred to me that this is likely to work, and work well — but customers will, of course, bear the expensive brunt of progress.
Bigger but not better
Understanding why T47 is a leap forward requires some thought as to why it came about in the first place.
“When I first designed the Argonaut frame, I wanted to use PF30 because it gives you a nice big canvas on which to work for the layup,” says Farver. “When we’re designing the shape of the frame, the BB is an area of a lot of complex curves. The bigger area you have to work with, the more accessible it is from a CAD standpoint. It also allows bigger tube diameters to increase stiffness and decrease weight.”
Of course, Farver, like just about every other manufacturer who transitioned to PF30, or worse, early versions of BB30, eventually started getting angry phone calls from customers who were experiencing consistent creaking. “That feedback I was getting just got really frustrating, and from the mechanic’s standpoint, shipping one of our bikes to a shop somewhere in the country, having a BB that’s too big and the frame might be undersized, you could damage the frame. Those were the two main drivers that led to the long-term solution.”
Farver knew the best solution was a threaded option, but going back to something like outboard bearing designs (think SRAM GXP) wasn’t practical because so many of his customers already owned cranksets with bigger spindles, which have their own advantages, primarily stiffness. So why not combine the ease of installation and reliability of a threaded system with the larger interface of PF30?
Farver contacted Chris King’s Jay Sycip and collaborated for almost a year to develop the threaded prototypes. Chris King has developed three versions of the new T47 system, which it’s calling Threadfit 30i. All three are designed around a 68mm bottom bracket shell with a 46mm bore, just like PF30:
• A 30mm version that accepts a BB30 crank. It also works with an adapter to run a 24mm spindle
• A 24mm version with external cups
• A Campagnolo-compatible version that accepts Ultra Torque cranks (Still in development)
The bearings used in each iteration are the same used in previous PF30 bottom brackets, available in both stainless steel and ceramic bearing versions.
The Campagnolo version is still in prototype form and is not ready for market from Chris King, but Bend, Oregon-based Argonaut Cycles will be selling cups sans bearings for Campy cranks, made by a local machinist.
Argonaut is the first company to actively use the products King is making, but it’s not a proprietary system, so other frame builders can adopt this open standard whenever they’re ready. In fact, during the development of the prototypes, it turned out that other companies were developing similar systems, so King got on the same page with those companies — White Industries, among others — to ensure this new bottom bracket has a fighting chance to become a true standard.
The price of progress
The new system rolls out in early 2016 with a reveal at the North American Handmade Bicycle Show in Sacramento, but it’s likely that larger manufacturers will be slow to adopt the new system that essentially requires a totally new frame for each model in their lineup on which they intend to use T47. And yes, that means consumers will need to buy yet another frame because the system is not backward-compatible (unless your frame is a metal PF30 frame, in which case it’s possible to tap threads into an existing PF30 bottom bracket shell; if your frame is carbon, you’re out of luck).
The cynics among us are likely to deride this new system as yet another don’t-need-it advancement for the sake of advancement. The problem with that argument is that T47 actually solves a pretty significant issue within the industry and has the potential to be a true standard, something PF30 attempted and failed. It’s hard to swallow yet another change that requires consumers to buy yet another expensive frame, but if the entire industry can get on board, the painful transition can be worth the effort: We know threaded systems work, and we know bigger bearings are advantageous to frame design and crank interface stiffness, not to mention bearing longevity. The real question is why it took so long for this to happen.