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Fixing a front derailleur with a broken spring retention tab (MacGuyver)

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Fixing a front derailleur with a broken spring retention tab (MacGuyver)

Old 10-20-17, 08:09 AM
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SouthFLpix
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Fixing a front derailleur with a broken spring retention tab (MacGuyver)

I have read that this is a common problem in Sora front derailleurs, but it can also occur in the higher tier derailleurs. What happens is the tab that retains the spring breaks off and there is typically no fix other than buying a new derailleur. This happened to me and I wanted to attempt a “MacGuyver fix” if possible, and to post it here so that if anyone else has this problem in the future it will show up in a search.

Basically what I did was drill into the portion of the derailleur where the tab broke off using a 1/16” drill bit. From there I cut down a finishing nail with bolt cutters, filled the newly drilled hole with epoxy, and hammered in the nail. I let the epoxy set for 24 hours and then filed it down to the proper length using trial and error. It works! (see photos)





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Old 10-20-17, 08:49 AM
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kevindsingleton 
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Well done. If there aren't any cracks or stress risers left from the tab breaking off, this should hold for a very long time.
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Old 10-20-17, 11:28 AM
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Much more elegant than my solution of using stretched sections of inner tube to pull the derailleur into its resting position. Still, the shifting worked at least as well as it did before the spring-retaining tab broke.
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Old 10-20-17, 06:36 PM
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Nice Job. I love it when people use some ingenuity to fix things. Send that photo to Shimano so maybe they'll redesign their derailleurs and possibly send you a new groupset (well, not likely but they should).
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Old 11-05-19, 12:11 AM
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This is exactly the solution and inspiration I'm seeking to repair two broken Sora and Tiagra derailleurs. But, why are the images showing-up so blurry that they're unreadable. I'm new to the site -- does it require a premium membership to clearly view the pics? Would love to see your handiwork. Please advise. Thank you!
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Old 11-05-19, 08:04 AM
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Originally Posted by dsrtdady View Post
This is exactly the solution and inspiration I'm seeking to repair two broken Sora and Tiagra derailleurs. But, why are the images showing-up so blurry that they're unreadable. I'm new to the site -- does it require a premium membership to clearly view the pics? Would love to see your handiwork. Please advise. Thank you!
The pictures are blurry because Photobucket is a subscription site and either they only display photos for a specified time or if the OP hasn't maintained his subscription, they no longer display the pictures properly. It has nothing to do with your time on this site.

BTW, I wonder about the OP's use of a finishing nail as they are pretty soft steel. Perhaps the shank of a 1/16" or 3/32" drill bit cut off using a dremel and cut-off wheel would be stronger and more durable.
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Old 03-28-20, 05:21 PM
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Attempting your fix

So... I was able to drill a similar hole and trim a nail - it fits
My problem is that I’m struggling reloading the spring tension behind where I need to insert the nail
how did you move the spring to the right position before you put the nail in the hole?
Thanks in advance!
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Old 12-13-20, 07:30 PM
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front derailer fix

So... I was able to drill a similar hole and trim a nail - it fits
My problem is that I’m struggling reloading the spring tension behind where I need to insert the nail
how did you move the spring to the right position before you put the nail in the hole?
Thanks in advance!
I used a small piece of brass tubing over the tab of the spring to leverage the spring past the drilled hole, inserted a drill bit as the nail I initially tried immediately bent
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Old 12-13-20, 08:27 PM
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Originally Posted by rocknoidl View Post
So... I was able to drill a similar hole and trim a nail - it fits
My problem is that I’m struggling reloading the spring tension behind where I need to insert the nail
how did you move the spring to the right position before you put the nail in the hole?
Thanks in advance!
I used a small piece of brass tubing over the tab of the spring to leverage the spring past the drilled hole, inserted a drill bit as the nail I initially tried immediately bent
rocknoid — I just did this same procedure about 2-3 weeks ago. I think I may have come across this same thread. A couple of comments. First — Don’t use a finishing nail. I did, initially, and had to redo the whole thing over again. That spring is so strong that after cycling the derailleur just a couple of times it simply bent the nail over and the spring came off. As luck would have it...I broke the 1/16th drill bit just as I got the hole drilled. SO...after redoing it all because of the bent nail...this time I just used the butt end of the broken drill bit. Drill bits are hardened and won’t bend. So...IMO...it might be worth it to sacrifice a drill bit just for this. But, don’t use glue to hold it in place, and don’t put it all the way through yet. The first time...with the nail...it literally took me about a hundred tries to get the spring contained behind the nail. Then, when the nail bent, I was pi$$ed!!! I can’t remember exactly what I did the second time. But it only took me about 5-10 attempts to capture the spring. I was using needle nose pliers, channel locks, all kinds of things. It was just very difficult to keep the spring compressed. I think in the end I kept it clamped down with channel locks and was able to get the drill bit through the hole. Success! I ended up not using any glue to hold it in place. That spring is so tight there’s no way it’ll move. But you can if you want. Won’t hurt. I kept thinking that it would have been nice to have a second set of hands (another person) to insert the drill bit pin while I held the spring. Hopefully it won’t take you as many attempts. Good luck.

Dan
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Old 12-14-20, 08:07 AM
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Same thing happened to me on my '06 Tiagra derailleur. Replaced it, but still have it. May have to dig it out to see if I want to try the fix. Seems like if this is a problem that the spring tab could be made a bit more robust to start with. Wasn't 14 yrs ago that it happened-was only 2-3 yrs after the bike was purchased.
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Old 12-14-20, 11:14 AM
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Yeah...the one I did mentioned above was a Tiagra also.

Dan
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Old 12-14-20, 07:05 PM
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BTW here’s a pic of my recent repair mentioned above.


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Old 12-17-20, 08:15 PM
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Why not keep it “pure” and use a piece of a spoke instead of a nail?
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Old 12-18-20, 03:24 PM
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Originally Posted by reconnaissance View Post
Why not keep it “pure” and use a piece of a spoke instead of a nail?
The 1/16 inch hole is 0.0625”...just about all there’s room for. Spokes are 1.8 and 2.0mm. That’s 0.0709” and 0.0787”

Dan
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Old 12-18-20, 07:14 PM
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Originally Posted by reconnaissance View Post
Why not keep it “pure” and use a piece of a spoke instead of a nail?
A spoke would probably not be strong enough and bend against the spring tension.
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Old 12-19-20, 08:32 AM
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Spoke would probably be stronger than the nail. But the nail definitely was too weak for that spring. The particular derailleur I did this on really only have enough space to drill a 1/16th hole. But other brands/styles might have more room, and allow a piece of spoke to be used.

Dan
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