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GUIDE: Repairing Shimano RX100 (A550) STI Levers

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GUIDE: Repairing Shimano RX100 (A550) STI Levers

Old 04-24-13, 05:47 PM
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GUIDE: Repairing Shimano RX100 (A550) STI Levers

Another guide, now for the RX100 STIs. These were in lovely condition, and its obvious they did not get much use over the years. However, the left hand shifter did not click at all. Right hand was quite stiff when clicking. Obvious signs of the gummed up grease.

RX100 levers are not symmetrical. The right side lever is different to the left side lever. So I will be going through both left and right sides in this guide.




This is the right lever. Remove the hood, and use a 2mm allen key to remove this grab screw. It does have a little bit of threadlock, so it may be a little hard to unscrew.


Use the same hex key to push out the pivot. Now you can take the lever away from the body.


Next, use a 5mm hex key to remove the screw holding on the name plate. Make sure youre holding onto both the name plate and the lever when unscrewing.


You will be greeted with this spring. This is different to the assembly of the new Sora(3300) and 105(5500) levers. Id say its much more easy to dismantle and rebuild because the spring is here.


Now flip to the back side of the lever. Push the smaller lever over so the screw is visible. Unscrew with a small Phillips, and watch out for the small washer underneath.


Now, just pull the lever right off. No springs underneath like on the new levers, so its very simple.


Very simple. The internal gears have been reached, and now you can ahead with cleaning it. I am using fuel, but you can use your degreaser, or whatever youd like.




Silly me forgot to take pics of when it was all clean. Oh well, you can find the pawls, and grease those areas up.
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Old 04-24-13, 05:49 PM
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Now onto the left lever. As you can see its different in shape.




Remove the hood, and use a 2mm allen key to remove this grab screw. It does have a little bit of threadlock, so it may be a little hard to unscrew.


Use the same hex key to push out the pivot. Now you can take the lever away from the body.


Next, use a 5mm hex key to remove the screw holding on the name plate. Make sure youre holding onto both the name plate and the lever when unscrewing. (Yes this is the pic of the right side, but its the same thing as the left)


Its odd that the spring stayed like this when I pulled it off. It should be like the pic of the right side. Pulled it out, and noticed the spring that was supposed to be bent at a right angle was bent to almost straight again. Rebent to a right angle, and everything was fine again.


Gummy grease!


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Old 04-24-13, 05:49 PM
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Now the left lever has a plastic cover which may get in the way of cleaning. Using a toothbrush, you'd get to most places, but there are places where you cannot get to. This is where I got my airbrush out and filled it up with some fuel. At max air pressure, I sprayed, and blocks of grease flew out. Keep repeating this til theres nothing else coming out.






You can go ahead and grease the pawls.

Final result after a polish of the levers. Would've liked to remove the rashes from the name plate, but preferred to keep the RX100 logo there.






Oh, and I will offer a service to rebuild STI levers. So far I have done the Sora(3300), 105(5500) and the RX100 as above, but I am sure that I can get around to doing the others without too many problems. I will also gladly take in any broken shifters, or ones that do not work anymore. Please PM me if youre interested!
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Old 04-24-13, 08:28 PM
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Great job and photoshoot.

Thanks for posting.

The only thing I would add is to apply a long-lasting oil to the pawl pivots before greasing, in the hope that the pivot is lubed and that any residual grease (which is inaccessible) would be re-hydrated.
The acid test is when cold weather comes, so I'm in the habit of freezing my serviced shifters to verify the pawl pivots are oily and not gummy inside.

These levers aren't so bad to rebuild when the inner mech is kept together, but that castellated nut that attaches the bracket was usually a pain to loosen until I modified a stout Vice-Grip plier for the job.

Again, good work!
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Old 04-24-13, 09:02 PM
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Nice write up! Thanks for the efforts and sharing!
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Old 04-25-13, 04:04 AM
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dddd, totally right! I only have dealt with these from the front, since everything would be accessible from there.

RSX shifters were rebuilt today, and the thread is up now!
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Old 04-25-13, 04:34 AM
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Hey, this is heaps easier than a full overhaul, and should be just as effective in making them work again... all the extra effort of complete disassembly (not to mention reassembly) isn't really worth the better clean and lube it enables.

I'll edit my thread on this to include this method and linkage.

Also, a couple of tips: it's not necessary to completely remove the easily-lost 2mm grub screw; you only need to back it out a mm or two on these levers. On the later plastic-bodied STIs, the grub screw goes past the pivot pin rather than onto it, so you you need to undo those 4 or 5mm. And sometimes it'll be seized; it can happen with ally or plastic ones... and a 2mm allen fitting is piss-easy to strip. So a soak in WD40 or whatever, maybe some tapping, and try this: 2 or 3 layers of aluminium foil tightly wrapped around the allen key. Twist the excess foil off the end. You may need to remove a layer of foil, but try for 3 layers first.

And you shouldn't try to remove the hoods unless you have replacements; they're hard to get off and on, and they get more fragile with age. There's no need for it unless you want to refinish the bodies.

And, you might find it easier to remove the name plate before taking the lever off the body. And I don't see much lube... grease on the pawls is a start, but I think at a minimum you also want a nice thick oil amongst everything else.

These first-generation STIs are one of the most ergonomic brifters yet made*, and if overhauled, they should keep going indefinitely. It's good to see a far more accessible method for reviving them. Come to think of it, this might even be possible when the lever can't be removed from the body because of a seized grub screw.

*I didn't fully appreciate STI until I switched my front brake to the right, and experienced braking to a stop and shifting to a low gear with a single movement... the moving brake levers are a feature, not a bug.

Last edited by Kimmo; 04-25-13 at 04:58 AM.
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Old 04-25-13, 04:39 AM
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Theres a thorough picture guide for the 6400 shifters here:
https://imgur.com/a/0tPBK
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Old 04-25-13, 05:13 AM
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That is an extremely excellent link which I am also adding to my thread.
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Old 07-03-13, 01:31 AM
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600 Guide is up!
https://www.bikeforums.net/showthread...%29-STI-Levers
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