Kudos to Wheels Manufacturing. They’ve made compatibility the cornerstone of their business. In so doing, they have made mixing and matching new and old components and across platforms incredibly easy and have taken the sting, and fear, out of purchasing many seemly-proprietary parts, and allow those with special needs to keep their bikes rolling. Want to get your Campy shifting to work with Shimano cassette hubs? They’ve got the solution. Need to find a shim to get your fork, handlebar, stem, front derailleur, seat post to work with your frame? They’ve got that as well. They even have pedal washers and derailleur hangers. Their BB30 Adapter for SRAM/Truvativ cranks is another such solution.
In the early days of BB30 bottom bracket shells, we bought a ‘cross frame that came with BB30. This wasn’t what we ordered and the shop kindly pressed in a bottom bracket sleeve so we could run a traditional bottom bracket and crank. That was fine until we looked at the weight. The sleeve weighed over 60g before we got around to the bottom bracket. Because there were no other BB30 options at the time, we sought out a Cannondale SI crankset and bottom bracket. Huge weight savings: the bottom bracket, including the spindle, weighed in at 126g, when the Shimano bb it was replacing weighed in at 232g. And the crank dropped another 100g plus from the crank we had been using. It was then that our interest in BB30 was really piqued.
Ever since that bike, we’ve eyed any BB30-equipped road frame as potentially our next frame purchase. The one thing that put us off was getting a power meter that would work on not only our BB30 bike, but would also work when we swapped it onto other bikes.
As time has marched on, BB30 has gained popularity, but, so, too, have stiffer, lighter thru-axle cranks and bottom brackets. Now the difference between threaded and BB30 is not as vast as it was just a few years ago.
With the proliferation of BB30 frames, Wheels focused their attention to making BB30 compatible with thru-axle cranks. They take two blocks of Delrin and turn them down so the resulting cups press into the BB30 bearings and then you push your thru-axle crank through the sleeves, and tighten it as you normally would. Same Q-factor, you’ve just effectively increased the diameter of the axle.
In terms of weight, the increase these parts result is a good bit less when compared to having a sleeve pressed in and then running a conventional bottom bracket.Our adapter cupsweigh in at 53g, only a slight savings over the 56g of the current SRAMadapter sleeve. But this isn’t where the savings comes. The weight savings comes from the fact that you don’t use a 115g+ bottom bracket in addition to the sleeve, but a 51-68g BB30 bearing assembly, a weight including the necessary spacers and clips. A SRAM Red GXP crankset is 656g, while the BB30 version is 591. While you are adding 102g when comparing the BB30 crank to the GXP crank and adapters, it is much lighter than the 170g or more you’re adding if you decide to have a sleeve pressed in.
The cups come in a thin bag with minimal instructions. So minimal, we ended up calling Wheels to find out if we should add grease to any of the interfaces. The answer is no. You press in one cup by hand or with a rubber mallet. You press in the other. There are different right and left pieces as the SRAM thru-axle is 24mm on the right side and 22mm on the left, and the pieces are clearly etched into the Delrin. When the cups are in push in your thru-axle crank, tighten to the torque spec for using the cranks with a GXP bottom bracket (the spec is basically “really hard”), and go.
That was it.
So easy. Almost too easy. But the cranks spun freely without a chain on, and they felt really stiff under full-on sprints. So they worked.
And because we were racing one bike on the weekends and riding another during the week, we pulled the crank off the BB30 bottom bracket and then replaced it a few days later several times. Generally we needed a mallet to start tapping it out, and once it was knocked a few cm, we were able to finish the job by hand. Occasionally, the right hand cup came off on removal. Occasionally, the left hand cup started to back off upon installation. For the latter, all we needed to do was hold it with one hand as we tapped the crank with a mallet and the axle slid through. Every time it functioned as well as the previous. And there was nothing to indicate that the adapters had worn in the least.
There’s no question that BB30 cranks are stiffer than the ones that rely on 24mm thru-axles, though it’s a difference that possibly not all of us would notice. We find ourselves wondering if these adapters potentially stiffen up the cranks further as the cups serve to increase the thru-axle diameter on the ends and through the bearings, possibly like double-butting the axle, just with a more pronounced step in wall thicknesses.
Another concern we have is water and dirt seeping through the tiny gaps between the adapter cups and the frame to eventually corrode the bearings. The clearance is really tiny, but there’s no doubt that water and grit could seep through. After a month of riding and swapping,a month of many rainy days and several bike washings, we noticed no grit seeping through the gaps. It could happen and probably warrants pulling the cranks and adapters every few months for road bikes and more often for cyclocross bikes. But considering how easy it is, and recommended service intervals, this kind of attention is hardly difficult or unusual.
As solutions go to the problem of adapting conventional thru-axle cranks to BB30 bottom brackets, the Wheels Manufacturing BB30 Adapter is exactly the kind of solution we love to find. It is light, simple, durable, and nearly idiot-proof.