Sunday, June 25, 2017

SRAM XX1 Cassette Removal: 

The Complete Fail


Despite the hopeful tone of my previous adventures with the SRAM XX1 cassette the future turned out to be significantly less than trouble free. After carefully installing the new cassette (thanks SRAM that was awesome!) using sterile procedures, grease, and a torque wrench the HFC had 3 fabulous seasons with it.  Nominally, it spends its life on the back of the SB95:




It receives little winter use and so accumulates miles more slowly than the ROS9, which is a superior PNW winter daily driver.



Regardless, in the later part of last season it became clear that the cassette on the SB95 had become a tad overripe. Not surprising, given that this cassette had participated in stretching something like 8 to 10 chains past serviceable spec. (The HFC is a clydesdale who enjoys standing to climb. Hard on chains he is.) It was time for a new one, yet here it remains:



Why you ask? The fear! The HFC has learned that the removal of the XX1 cassette requires MORE care and preparation than has previously been revealed in these pages! In fact, it may not be possible without what many would say are extreme measures. And, predictably,  the HFC has learned this The Hard Way.

The Hard Way


Not long after the HFC broke the axle in a Stans 3.3 hub he replaced the Stans wheel-set with a pair of OnyxRP hubs and Arc30 rims.


Wow. This new wheel-set was a game changer. An instant engagement and totally silent hub + wider stiffer rims. And it appears to be bomb proof, and not just because it's already taken a year of hardtail smacking from the HFC.

I rode the living crap out of them for the next 9 months, jumping, drifting, railing and grind-grind-grinding in every type of PNW climate joy. The ROS9 is HFC's first choice for any ride under 2 hours and even for longer rides it whispers "Take me!" as he starts to prep the SB95. For the HFC, the ROS9 XL with the new wheel-set is something beyond the sum if its parts. Magic. 

Anyway, in September the Hoosier, the HFC's life long friend and fellow bikes are the best compadre from Indiana, arrived. The Hoosier arrives with a ROS9 (nice) adorned with the stock Stans 3.3 wheel set. (Can you see where this is going?) September is the Best month so the two friends got right to it with the riding until on day three of the trip the Hoosier's drivetrain starts to act up. Sure enough, another broken Stans 3.3 hub. No Shit. But no worries! The HFC can switch to the SB95 and loan the Hoosier his spiffy OnyxRP rear wheel. Just a matter of switching the cassette and rotor.

Knowing that SRAM X1 cassette removal is troubled territory, the HFC proceeds cautiously, keeping in mind everything he learned about this lovely but finicky part. After selecting the correct deep socket style cassette removal tool and inserting it fully into the cassette he locates the proper wrench for the cassette tool, addresses the 2nd to largest cog with the chain-whip and applies gentle pressure. 
Nothing moves...
So a wee bit more pressure...
And nothing. 
And some more... And just a bitCRACK. 
Yeah. 
That. 
Every single tool engagement tooth on the center sleeve of the cassette has been sheared away. 

At this point one might imagine that the cassette just fell apart, but no, it was not the case. The cassette is still held firmly in place by threads inside the (now hopelessly mangled) center sleeve. 

For a period of time the HFC was all f--- this and f--- that. And having clearly done so, he finally wised up, grabbed the spare wheel set off the wall, dropped the Hoosier's cassette and rotor on to it and was off to the woods for more riding and camping and fun. After several more epic days they return to the Lair and examine the situation.

A plan emerges to recover the hub and wheel, as the cassette is now just in the way.

Emergency SRAM XX1 Cassette Removal Procedure

Tools Required 

  • Giant DIY chain whip
  • Pipe wrench (yeah, old school)
  • Four inch angle grinder with abrasive cutting disk
  • Ear & Eye protection
Notes:
  • Before stepping up to the pipe wrench the HFC tried the maneuver with a strap wrench. No recommended.

Get rid of all those pesky cogs. 



The HFC made 4 or 5 radial cuts across the web of steel that forms the 10 smallest cogs. To fully break it free the web of small steel connective tissue connecting the 14 tooth cog to the 16 tooth cog must also be cut with the angle grinder. Do This With Great Care. Once these cuts are completed the cog set can easily be removed:



Make a ridiculously big chain-whip.

The HFC started with a 2ft fir 2x2 and a dead chain. That lasted about 10 seconds. Falling back to the scrap heap he located a 3ft piece of 3/4" x 1 1/2" oak, which worked but just barely. It also important to have a nice long piece of chain as this allows for a full wrap on the cog which decreases the risk of it jumping a tooth.

Apply chain whip to the remaining large cog. 
Apply pipe wrench to the now exposed center sleeve. 
Get on it:

 

Remove center sleeve and large cog.


 


Done!

The deed complete and the hub and wheel rescued from the claws of the XX1 cassette.


\

If you have to try this at home, be assured that you have the HFC's deepest mechanical and monetary sympathy. If you have to try this at work, well, hopefully you won't also be buying the new cassette.

Later,

HFC



No hubs and a single XX1 cassette were damaged in the making of this story. 


Wednesday, February 17, 2016

Poetry


Archly the maiden smiled, with eyes overrunning with laughter - H.W. Longfellow

Saturday, January 2, 2016

Did you hear that?

ROS9 Stock Rear Wheel

The other day, a bright sparkling early winter day with a sprinkling of the icy bits, the HFC rode with friends to the top of a local favorite "flow trail". Ingeniously built using (gnome) hands and machinery to allow even a moderately skilled rider to flow far above their actual abilities. After an easy "typical government graded road" ride we arrived at the top, switched up clothes, had a snack, and dropped into the trail. Which opens with a wee pump up over a root ball. Which I intended to do. Pump up over the root ball. But, age, lack of skill, and a general lack of balls sent me in a bit slow so I had to pedal at the top.

But... wait! No chain! Now that's odd... You see, this hasn't happened to the HFC but maybe once in two years since he switched to a 1x11 drivetrain with a clutch type derailleur. And that one time it was a small fir cone that got picked up by the rear wheel, carried round to the chain stay yoke, where it was peeled off the tire. Just in time to be picked up by the teeth of the crank and carried up into the chain, dumping said chain smoothly off the chainring.

So after checking for stray vegetation, I put the chain back on, turned around, and rode back up. I hit it again and... same thing. Although this time I notice an odd noise, like the rear fender rubbing on the rear tire. So back up for another try and... same. At 0 for 3 I put the chain back on and went on down the trail.  Eventually I was able to see that every time I pumped a feature (crouched down and pushed off the pedals) the freehub would lock up and I would be riding a fixed gear. While locked, the cassette would then squirt chain towards the crank above the chain stay. As my weight came off the rear wheel the freehub would unlock and the derailleur tension would retrieve the squirted chain with an audible zzzzzip-clack sound as the system came up snug. Pedaling before or during the  retrieval would cause the chain to drop.

So while zooming along, try to adapt my rhythm to accommodate the gross shortcomings of my drivetrain, I found myself preoccupied with the question:


Why?

I had only two suspects: The freehub body, or a broken axle. But every freehub I've blown up (or seen blown up) simply turned into a full time fixed gear, none of this "it works great except when..." business.

And it did work great. Climbing seated, climbing standing, coasting mellow stuff, or even rock gardens. Worked just fine. Except when...

So I concluded that it must be a broken axle. The hub (Stan's 3.3 with XD driver) was set up with a 12x142mm axle system. Which was assembled plenty tight. And the wheel was still attached to the bike, so the 12mm axle wasn't broken. But, see that's that's not really the axle, the 12mm "axle" is an attachment system that could more rightfully be called a heavy duty skewer, just not a quick release one. The actual axle is the cylinder in the hub to which the bearings are attached and through which the 12mm axle slides. Because the 12mm "axle" is big and solid and strong I figured that it could be holding that hub together pretty well, even is the real axle was broken. However, the huge additional load (of a fat ass biker) pumping features could potentially cause the hub/axle to flex and jam the free-hub.

I finished up the ride, drove home, went to the LBS and was able to demonstrate the phenomena to him on the sidewalk in front of the shop. Interest piqued, the LBS dove in and tore it down to find: A broken axle

 Click here to make it bigger
Stans 3.3 Freehub Body

Stans 3.3 Rear Hub Drive Side Internals


But why? Was it all about being Ham Fisted? Smashing ye olde hardtail into stuff? Going too big? Or was it just being too big? Too many chips? Too much chocolate? 

Or maybe something else?

Well, there's this:
Stans 3.3 Rear Hub Shell Exterior


All those pawls and clicky bits all the set in the far end of the hub, and as soon as practical, the hub body narrows considerably. Compare that with, say, a Chris King:
 Chris King ISO 142x12 Thru Rear Hub
Chris King ISO 142x12 Thru Rear Hub

Positively chubby. Because that makes it stiff and strong.

So there ya go. 

Time to go buy some more chocolate.

Afterward

Six months after the HFC destroyed the Stans 3.3 hub he was railing corners on the new wheels when there was a loud CRACK followed immediately by some extra special rear wheel lockup. Closer inspection revealed that the Maxle (the same one that endured the broken hub and then been placed into service in the replacement wheel) had broken:


If worked for while, but was probably terminally damaged in the previous incident.








Monday, December 7, 2015

Lucky




The HFC is in bed. It's a spring morning, just getting light. And his wife is there with him. She's clearly exasperated and, less obviously, worried. Maybe even scared. She's saying to him: "Look, I can't keep telling you this over and over... Just let it be. Maybe later you'll remember more."

Now,  you see,  I remember this scene and the things that happened after it. I do. Right now, months later I remember it clearly. But the thing is: The minutes and hours leading up to that moment are completely gone. Lost in the impenetrable darkness of a traumatic head injury. In the end I only lost about 24 hours of my life to that black suck, but I was super lucky. Lucky to be with a friend and not alone. Lucky that friend is an old hand at assessing the injured and getting organized. Lucky that my helmet did its job. Lucky it wasn't worse.  Lucky that I got better quickly.  And lucky that in 24 hours I snapped out of rebooting every 90 seconds and returning to:

"Did I break my helmet?"

Every time.

No, seriously, every time.  Hundreds of times. Some people stay there for weeks, I did not.

Yes. You broke your helmet.
Concerned people ask: "Was it scary?"

Well, from here, no.

Because I don't remember how it was not to remember. How it felt to be unable to remember the plan, the sitting president, the date, the house I live in, my son graduating a week before. What it was like to come to consciousness and be changed. And if I did manage to feel the awfulness of it, within 90 seconds it was erased by a reboot and a return to:

"Did I break my helmet?"

I struggled a long time with "What happened?": Was I going too fast? Did something distract me? Did shit just happen (to me)?

I had a fair amount of time to contemplate all of this as I was banned from anything resembling reading, computing, tv, music, or exercise for a month after the crash.

Watch clouds. Think stuff. Sleep. Repeat.

I spent some of that time relearning to feel my heartbeat all through my body, working on breathing through the rhythm of it, breathing in the spaces between the heart beats.

I don't know what happened beyond that I crashed really hard.

But I do know I've been lucky beyond words.






Thursday, January 9, 2014

Tripping Over The Little Things

It always seems to me that attention to detail is crucial. Yet, my attention is a precious and surprisingly limited resource. So every now and then (and more often than I care to admit) my attention is not on the details of the task at hand but rather somewhere else: On the awesome King Floyd track "Groove Me" from the Atlantic R&B box set I got for x-mas; Or my day job; Or my pernicious injuries that keep me off the bike (thankfully it's the off-season); Or even the anticipation of some quality time with my sweet loving wife.

All that stuff shifts my attention around from the matters at hand like a business of ferrets running through my head, so that I suddenly find myself looking at this:



Many of you may already recognize this nasty little bit of twisted aluminum. 

What's that? 

You don't? 

Here's a hint:


That's what happens when you start trying to align your brake caliper with your new 200mm rotor using your swanky new 6061 T6511 Aluminum post mount adaptor and you take your eyes off the ball because one of those pesky mental ferrets comes calling.

See, at first everything looks great. The mounting bolt is plenty long:



And it mates up the post mount adaptor just dandy:


But after 30 minutes of fucking around, truing the rotor in the stand and generally getting irritated you decide to add those lovely hemispherical washers to the mix because the damn thing won't stop rubbing:


But you fail to observe (well I suspect at this point you didn't fail to observe) that the bolt is coming up short. Because even though it looks just dandy assembled:


Torquing things up leaves the bolt, well, oddly not so tight. In fact a careful tug with the fingers and out comes the little fucker, surrounded with the guts of your precious post mount adaptor:


Leaving your little piece of awesome bike jewelry eviscerated:


It should look a lot more look like this:


That hemispherical washer seemed like a great idea, but it soaked up a few too many threads. And in one of those mystical moments once removed it seems to have been one hell of a lot thicker than it appeared when it was in the stack:


Luckily for the me I had an extra post mount handy and I'm already back in business.

Remember people: 
Your attention is a limited resource. 
You only have so much of it to give in this life. 
Use it wisely.

The HFC.





Monday, December 9, 2013



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




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.