TINY SPLINES WON’T ALIGN

Q: Hey, MBA, I’m in a state of frustration right now. I’m trying to mount my microspline 12-speed cassette to my new wheelset and can’t seem to figure out the final little cog. I see the keyed gaps it’s supposed to rest in, but it won’t sit flush with the rest of the cassette! What am I doing wrong?
Lyle Thompson
Tallahassee, Florida

A: This is a problem we’ve actually had quite often. It can be easy to get it wrong if you’re not paying attention or have never mounted a microspline cassette on a freehub body before. As you well know by now, the splines are small, and can be hard to see where the gaps and whatnot are in reference to each other. The 10-tooth cog is particularly hard, as it has two larger areas that need to be aligned that look unfortunately similar to each other but cannot be switched around or you’ll have the problem you’re currently dealing with. Sometimes it sits flush enough that you don’t notice at first and try to install the lockring and risk stripping the threads.

There’s an easy way to check to see if you’re putting it on the right way. When you’ve installed all the other cogs, set the wheel down and really look at the 10-tooth cog in your hand and identify the two larger spline gaps. They’ll be directly across from each other on the cog. If you look closely, you’ll see one of these large spline gaps has a spline next to it of equal size, whereas the other one has small splines on either side equivalent to the tiny splines lining the rest of the cog.

Mark the gap with the larger spline next to it with your finger and study the cog it mounts to. You’ll see matching large splines there with only one larger spline with a similar-sized gap directly mirroring the one you have marked with your finger. Now, carefully lower the 10-tooth cog so the marked spline is near the other one, and rotate it until it drops in. Of course, you’ll still want to check that it’s flush, but if you’ve done it right, you should be able to screw the lockring in right away. We hope this helped your little dilemma.