Race Face’s latest cranksets and Rotor’s Rex cranks both use a 30mm spindle designed to work with virtually any frame, though some of those frames may need their external cup threaded bottom brackets. But, if you’re running a frame with BB30 or PressFit30 shells, Praxis Works’ new M30 Thru bottom bracket could be the upgrade you’re looking for.

Not only should it do away with most spacers, but it pushes the bearings outside of the shell for a wider stance. That should make the entire assembly stiffer. Even better, it uses their expanding collet system to essentially lock the BB into the frame so it can’t creak, rock or walk out. A compressible O-ring on the non-drive side ensures a snug fit against the frame despite any out-of-tolerance issues your particular bike may suffer from.

Because the two sides thread together, the bearings remain in perfect alignment, leaving the spindle to spin freely. Retail is $85, but they recommend using their M30 tool to press it in…


The tool ensures scratch free installation and is available separately and are needed for proper installation.


The forged and machined heat treated alloy cups and shell hold high quality steel bearings. It’s designed to fit bike running ISCG05 and seat tube mounted chain guides, but won’t work well with ISCG03 mounts. The part is sized to fit 73mm mountain bike bottom bracket shells only.

Available in October 2015.


  1. Gotta love men and women of industry, looking for opportunity instead of whining about inevitable and constant change. Right on Praxis, first fixing Shimano’s arrogant or short sighted handling to change with the BB spindle diameter and now tooling up for another model BB for the lightest mtb production cranks and some of the most bad ass looking cranks on the market. No I am not a Praxis shill, I don’t even own any of their product, but I have installed them for customers and they are solid kit.

  2. Hey there’s a concept that works, twenty million other threaded shell designs emerge, but no matter how many shells in the sea, it would be so annoying without a 68mm threaded bee bee

  3. Praxis won’t stand behind their product. Received one on a new fuji bike that was seized and needed out because shimano crank. Only offered to sell me another. Would not recommend.

  4. No I am not. I called and emailed praxis and got basically “You are a 1 in million chance of issue, and we are sorry but we are on the tour de france!” They offered to sell me at price on amazon for basically a failed product from the factory of fuji. Whose fault, who knows… but not going back and went with wheels mfg over it and upset enough to post here months later. So let that soak in how praxis treated me that I spent the time posting this… (deleted)

  5. 1 set of threads is better than 2 to hold a BB in place, and you can’t ruin the frame threads because there are none. this is nice.

  6. BB30 and 24mm axle bla bla , go ride your bikes.
    no one cares.
    by the way praxis put my bike shop on there where to get there products when we have never heard of them, had people phone up and ask for there product,when we told them we had nothing to do with them, the people who phoned went ballistic.
    good thing we do not carry any product from them,dont want that type of customer in my shop,unable to understand that I had nothing to do with anything at all , yet it was my fault.

  7. Praxis, just in case you’re looking…

    I would love if there was a solution like this (cups seating into one another with perfect alignment), but to allow you to put in a Squaretaper bottom bracket into a PF30 shell.

    Not the most common scenario ever, but that’s almost the only bottom bracket compatibility option not currently available, and you have the technology and parts to make it happen.

  8. My only real beef with Praxis is they don’t make a BB86 bottom bracket to work with a 24mm crank spindle.

    If you want anything BB86 from Praxis, you’ll need to buy their cranks…which are 30mm spindle. Kind of a missed opportunity there, methinks.

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