At Suntop 50 I came to the nice free mechanic 30 minutes before the race asking if he could take a look at my rear derailleur shifting. He checked it and the rear hanger is bent a bit. He tuned it as best he could, tried to straighten it but said it would need replacing. The last thing he did, and I remember this now, he took a T25 wrench to make sure the derailleur was tight. He tried to tighten the hanger and couldn’t make purchase on it… hmm. Isn’t that supposed to be an allen? He tried an allen and made a face like… yep its tight.
Rode race and rear derailleur shifting was the least of my problems. I’m thankful for his time.
I go online and order a new hanger from Yeti ($20 + $8.50 for slow shipping). Hanger eventually arrives, time on the weekend. I get a flashlight to check what kind of wrench I should use and… its all silver in there… really badly stripped. I try to get an allen to fit but it just rotates with a bit of resistance. I try pounding in a Torx 25 but no dice. A few times I get a good purchase but the bolt doesn’t want to come loose.
Ok… Hmm. At least the bike is rideable, can keep riding until I figure a solution. Obviously I’ll need a new pivot bolt though because the current one is toast and will be super toast when I’m done with this job. Order new bolt from Amazon of all places, $17 for the kit which includes the hanger stop, two different washers and the bolt itself.
Kit arrives and then a weekend with freetime. Need to be able to finish the job before I start, otherwise I have no bike to ride.
First idea is to use a “drillout kit”, I have one from stripping other bolts. Unfortunately I don’t have a 1/2″ drillout bit. The inner diameter of the pivot bolt is > 3/8″ on the outside of the frame, and quite small on the inside but… if I want to drillout from the inside I’ll need a normal direction drillout bit.
HEY! I know, I’ll make my own “normal drillout bit” and screw in a burly stainless #10 metal screw into the inner side of the pivot bolt, that lets me apply a bunch of torque to the bolt to unscrew it from the hanger. I gently clamp hanger into vice and slowly drive screw into inside of pivot bolt from the “inside”. Right hand torque from inside is left hand torque from outside so it should drive pivot free. Screw slowly threads in, then torque increases. I gently ramp up torque on my corded half-inch drill and… the head twists off the screw. Serious torque and the pivot bolt doesn’t come loose!
I use channel lock pliers to twist screw end out, try again and same thing happens. The pivot bolt is really bonded to the hanger! No wonder the bolt was stripped inside, this bolt wasn’t coming loose!
Checking how pivot bolt attaches to hanger it looks like there is room for an angle grinder,
Hey, I know. How about the angle grinder!?
I can cut most of the hanger away from the pivot, eventually I’ll be able to pry the pivot free?
Hanger again lightly clamped in vice. Glass of water handy so derailleur doesn’t get too hot. Start at 1000rpm with universal grinding disc.
Things to notice:
- Both the yeti hanger and the sram bolt are made from REALLY nice aluminum. Grinding disc takes its time with this stuff.
- Only grind for 4-5 seconds at a time. Make sure the water never boils. Wait for it to cool before grinding more. Angle grinder can generate serious heat, usually the disc is red or orange when grinding steel. Would cook the poor derailleur and maybe anneal it?
- Angle grinder has great control, no problem avoiding the parts I’ll be keeping.
Eventually I’ve ground through enough of the hanger that I can pull one side free. Put big allen inside pivot and pull, there is a CREAK and the pivot bolt threads detach from the hanger and I can see the pivot threads. Those suckers were really stuck together.
Now to remove the pivot bolt. Pivot bolt is attached with the following features:
Pivot bolt has threads at the end to go into hanger.
After threads is a shallow groove. This groove holds a “spring clip”, its a coil of flat wire that looks like a washer.
Under the spring clip is the hanger-stop ring
Under hanger-stop ring is a wave-spring washer.
Under wave spring washer is the derailleur.
Pivot bolt goes through derailleur and has a head on the other side.
Wave-spring exerts pressure to keep hanger stop ring and derailleur apart, basically it keeps the pivot head tight to the derailleur.
I fiddle with pivot bolt for 10 minutes or so. Can’t figure out how to remove the bolt. Read on interest it suggests using a small screwdriver.
I catch the ring with the tip of a razor, it lifts out and expands to show its a spring clip. And once it’s out the pivot bolt is free.
Clean everything, then reassemble.
I had a devil of a time getting the new spring clip into place. The trick turns out to be:
- Place allen tool into pivot bolt, this is your derailleur stand
- Realize the spring clip is a coil
- Split the coil so you have an end in your needlenose.
- Press pivot bolt into derailleur so groove is visible (need good light to see this!)
- thread end of spring clip into groove, then use small screwdriver to press from end of clip around until entire clip has been threaded into groove.
Now secret trick: apply a single wrap of plumbers tape to pivot bolt. The problem is that the derailleur hanger is seriously exposed and grease washes away (I hope it was greased!) Plumbers tape will keep metals from welding themselves together.
Finally… was it worth it? Was hanger bent? Looks like it actually was!
A few shots of installation onto frame.
Good news is that bike shifts really well now. No issues. Glad I did it but cost 5 hours of research and labor + $45 in parts. Would have been much more if I’d left it at a bike shop. A shop mechanic suggested I just get a new derailleur (at $250!).
Hindsite… I know how to do it now. Probably could do it again in 2 hours. Depends what your time is worth I guess.