Originally Posted by
Dee Hubbs
All forks with a 15mm though axle accept an end cap the size of a NICKLE. The nickel sized end cap slots nicely in the cutouts in the forks, and the 15mm axle snugs everything up, and carries the weight and support. The nickel is industry standard.
Sram came up with Torque caps, and increased the cutout in the forks to accept an end cap the size of a QUATER, so now you can replace your "industry standard" nickel sized end caps with end caps the size of a quarter. The 15mm through axle still carry all the weight, but according to SRAM the Torque Caps creates more surface area between hub and fork, and is "xx fake%" stiffer.
Every non Torque Cap (nickel) hubs can still be used in in a Torque cap (quarter) fork (just not optimized)
BUT
Torque Cap (quarter) hubs will not fit in a non Torque Cap (nickel) fork (ie Fox).
OR
You can still put your nickel in the quarter slot, but you cant put your quarter in the nickel slot. (why is the dime smaller than a nickel and penny?)