In development for a few years now, Praxis Works’ line of Turn cranksets are starting to find their way onto road bikes in the wild. Now, you can add mountain bikes to the mix. Created as both an OEM and aftermarket solution, Turn cranks are built with stiffness in mind with hollow forged arms and a 30mm aluminum spindle. In fact, in a recent stiffness test carried out by Fairwheel Bikes, the Turn Zayante 2015 road crank had the least deflection of any crank tested. It was also the heaviest modern crank they tested, but the Praxis Works bottom brackets trade off a bit of weight for durability.
The Girder M30 MTN crank looks to bring the same level of stiffness to mountain bikes. Currently in stock and shipping in select sizes, the M30 crank relies on the same 30mm spindle and bottom bracket technology as the road crankset just with mountain gearing. Girders will ship with either a 2x ring combination or one of Praxis Works’ own Wide-Narrow chainrings including the new 30t…
When not using a single chainring in the 104 BCD outer arm position on the spider, the cranks can be run 2x with the 104/64 BCD spider. Available in 165, 170, 175, and 180mm crank arm lengths, compatible bottom brackets will be offered for threaded 68/73mm shells as well as PF92, and BB30/PF30 frames.
As mentioned, the Turn Girder M30 crankset relies on a 30mm aluminum spindle for stiffness, that tapers down to 28mm at the crank. The hollow forged arms aluminum and a forged AL spider should provide plenty of stiffness based on the numbers from their road cranks. Sold as a 1x drivetrain with either a 30 or 32t Praxis Wide Narrow chainring, the cranksets are currently available in only the 175mm length for $279 with more options on the way. That price includes the chain ring and an M30 installation and removal tool, but bottom brackets are sold separately for $50-85.
Earlier this year, Praxis Works introduced their new Wide-Narrow chainrings with a run of 32-38t rings. Unlike the rest of their chainrings which are forged, the Wide Narrow rings are stamped from a 4.5mm thick plate of 7075-T6 aluminum and then machined. The new 30t chainring undergoes the same construction process but adds the additional machining of the threads so the smaller ring can still fit on a 104 BCD crank.
Like other 30T/104 BCD single rings, the Praxis ring requires male M8 chainring bolts with a minimum length of 7.5mm to ensure proper engagement. Hard anodized and compatible with 10/11sp Shimano/KMC/SRAM, and 11sp SRAM XX1 chains, the rings are recommended only for use with a clutched derailleur. Likely due to the extra machining involved, the 30t rings are $25 more than the rest of the chainrings and sell for $75.