Thru Axle Compatibility

How Did We Get Here

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Disk brakes are becoming more and more popular each year and the number of newer road  bikes using disk brakes just about equals those with traditional rim brakes.  So we are expecting to see more people coming to the Indoor Cycling Time Trials with bikes using disk brakes.

 

However, disk brakes create some challenges for those who use their bikes for indoor training or use stationary trainers for warming up at races.  And that includes us at the Indoor Cycling Time Trials.

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Most of the bikes with disk brakes are using something called a "thru axle" to attach the rear wheel to the bike.  Bikes with thru axles have holes in the frame instead of notched dropouts.  The thru axle goes thru a hole on the left side of the frame, thru the hub of the wheel, then screws-in to a threaded hole on the right side of the frame.  The bike frame is beefed up around the rear axle to handle the disk brake hardware and the holes for the thru axles.    

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Here are some of the challenges when trying to connect a disk brake bike to a stationary trainer.     

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There is typically no axle or nut sticking out of the right side of the bike frame to use to connect to a trainer.  An adapter is required to allow the connection.  

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Unfortunately, bike manufacturers have not agreed to a standard for thru axles so length, diameter, and thread count vary considerably.  Different bike brands need different adapters.  Verify with you bike shop before purchasing an adapter

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The spacing of a rear disk brake hub is wider than traditional road bike spacing.  Traditional spacing for 10 or 11 speed road bikes has been 130 mm for many years.  Disk brake hubs are wider to allow for the disk brake rotor attachment flange.  Currently, it seems many manufacturers have settled with 142 mm for rear axle spacing. 

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The wider hubs, thicker frames, and need for adapters for thru axle bikes have made it difficult, if not impossible, to use with existing stationary trainers.