SRAM XX1 Cassette Removal: 
A Certain Amount Of Fail

Background

I have to admit that in general I am a rider that prefers SRAM to Shimano. It's not because I think that SRAM kit works better - both companies make great stuff. I just keep finding little ways that the good people at SRAM tickle my fancy and other ways in which the Shimano kit does not. This, unfortunately is not one of those stories. This is a story about how crappy eyesight, crappy service manuals, and state of the art manufacturing came together to destroy a $425.00 (if you're paying retail) part.

Behold the technological and manufacturing marvel that is the SRAM XX1 Cassette:

XG-1199

This piece of total badassery is constructed from exactly three pieces: The ten smallest cogs are machined from a single billet of cast tool steel:

To this an inner sleeve that serves as the lock ring is added:

And the largest cog is affixed to the back to complete the cassette:

It's a radical design that decreases the weight of the system while increasing the durability. (If SRAM is to be believed this thing should last 4 times longer than previous versions). To make it all work they had to design a new free-hub body: One that utilizes the largest cog to transfer the entire drive torque to the wheel, and that is threaded to accept the inner sleeve assembly. The one thing it seems they didn't change was the tool needed to take this thing on and off your wheel. In the SRAM service manuals and online videos they emphasize that the "regular" tool is used to install and remove the cassette. Which brings us to my little story...

Removing The XX1 Cassette

All the available information (SRAM service manuals, online videos produced by SRAM, etc.) indicated that removing the XX1 cassette required only the "normal" tool. I grabbed my trusty Park FR-5, clamped it onto the wheel using an old skewer, dropped it into the bench vise, applied ye-olde chain whip, and… um… wait. This seems really hard, like way too much effort. Maybe the shop monkey that assembled this thing went a bit overboard? I looked at it closely. I checked the web again to be sure I wasn't missing something. Sure seemed like I was doing the right thing. Applied a bit more pressure and… 

CRACK

That was SO not the kind of noise I wanted to hear coming from my new toy. After removing the Park tool I could immediately see that very bad things had happened:

Here's what it's supposed to look like:

So what happened? 

The wheel in question has a 142x12 mm through-axle hub. The Park FR-5 tool bottomed out on the end of the hub's axle shaft housing. This caused it to superficially engage the teeth in cassette. In old style cassettes that utilize an end-cap style lock ring the lock ring is only 1 - 2 mm thick so deep engagement of the removal tool is not required, and in fact doesn't improve the "hook-up" of the tool due to the construction of the lock ring. However, on the XX1 this is not the case. The "teeth" that the removal tool is engaging are in fact the very end of the inner sleeve:

You can see in the cutaway where the inner sleeve of the cassette enters into the end of the cog body (starting at cog 9) and forms the teeth with which the removal tool engages (inside of cogs 10 & 11). These teeth are aluminum and they are both long and thin. If the tool doesn't engage the entire tooth you run the risk of snapping off some or all of the tips or even entire teeth.

Here is what the Park FR-5 tool looks like when it's seated in the XX1 cassette when the cassette is NOT mounted on a hub:

And on the inside of the cassette we can see that the Park FR-5 splines are almost long enough to fully engage the splines in the XX1 cassette's inner sleeve, when the tool is FULLY seated:

However, when mounted to a hub with the XD driver body and a 142x12 mm axle the Park FR-5 bottoms out on the axle shaft housing. Here is the end of the axle shaft housing on a Stan's 3.30 hub with the XX1 securely mounted to the free-hub body:

And here is the Park FR-5 clamped firmly in place "ready" to "engage" the cassette for removal:

It's clear that the tool is not seated nearly as deeply as when the cassette was not mounted to the hub. Let's look more closely:

Actually - it's not seated at all! A careful inspection shows that only the very tips of the Park FR-5 tool's splines are engaging the very top of the splines of the cassette's inner sleeve:

In fact, with somewhat different lighting you can actually see light through the spline interface:

That's something like 1 mm maybe 2 mm at most of overlap between the tool and the cassette. And that is the root of this entire problem. Put torque into this configuration and nothing good is going to happen, as I found out. I suppose if my eyes were better or if I had been wearing something like 4x readers I might have been able to see this before I trashed my cassette, but such was not my fate.

Why does it matter?

As far as I can tell the tips of these teeth are the only thing holding the cassette onto the free hub body! On the part I broke:

Four teeth lost their tips and a fifth tooth is snapped entirely off. The remaining seven teeth are deeply scored by the tips of the Park Fr-5 splines. Sure, if your wheel is securely mounted to the bike the only place this thing can go is into your frame, so it's not like it's just going to fall off your bike. But the sorry truth of it is that this cassette is ruined.

And that my friends is a potentially expensive lesson.

Now, you may have already noticed that I have a bunch of pictures featuring the Park FR-5 tool interacting with a sparkly new undamaged XX1 cassette. That's because the fine, wonderful, truly awesome people at SRAM, after hearing my story of woe (via my equally awesome local shop) saw fit to send me a "goodwill" replacement cassette. 

And that should be the end of this story.

But it's not. 

Why? Because the folks at SRAM are still telling the world to use the Park FR-5 tool to install and remove the XX1 cassette! Here is the packing slip that came included with my (super! awesome! generous!) replacement from SRAM:

And that is just WRONG. I suppose the Park FR-5 might work on a traditional 135 mm quick release axle with the XX1 cassette (I haven't checked).  And maybe, just maybe, it might work on a different 142x12 mm hub from a different manufacturer (but I seriously doubt it). 

What to do?

Well, whatever you do:

DO NOT USE THE Park FR-5 TOOL TO INSTALL/REMOVE THE XX1 CASSETTE!!! 

DO.  NOT.  DO.  THAT.

At least, don't do it before you make damn sure that the Park FR-5 tool is actually fully seated in the cassette before you apply torque. If it does not fully seat because the aforementioned reasons (or any other), try using a deep well removal tool like the one on the left:

That's an "XLC" deep well removal tool on the left, Park FR-5 on the right. The XLC is not the only choice. All that matters is that the interior well of the tool be deep enough that the tool doesn't bottom out on the end of the axle shaft housing so that the splines seat fully into the XX1 cassette.

You want something like the one on the left. Really. You Do. Seriously.

Here is the XLC tool fully seated (without a clamp) on the exact same Stan's 3.30 142x12 mm hub with the same XX1 cassette mounted to it:

That's going to work great. Plus, unlike the Park FR-5, if you clamp it in the vise on the faces with the shoulder it won't fall out of the vise, land on your foot, and then roll under your workbench into some unreachable corner of dust rhino hell every time you loosen the vise jaws.

Regards,

The HFC

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2013/12/23 Update:

Today friend sent me these pictures of the Park FR-5 tool seating correctly into his XX1 cassette mounted on an older Stan's 3.30 hub upgraded with a new 135x9 mm QR axle to accommodate the XD driver body:

Poised for insertion:

Fully seated:

So there you have it, my speculation was correct: The Park FR-5 works with the XX1 cassette in some axle configurations and not in others.