Bicycles Stack Exchange is a question and answer site for people who build and repair bicycles, people who train cycling, or commute on bicycles. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

The Simplex SX410 rear derailleur on my bike was dirty, so I got it off to clean it.

Yet, now I can't quite seem to get it on again in a correct way.

Specifically, I can't get the spring to be wound up correctly (the derailleur hangs quite loose).

Is there anyone here who has got the same derailleur and actually knows how to put it on correctly?

share|improve this question
Try Campag instead! Ha Ha! Much better quality! – user4782 Aug 15 '12 at 13:14
Also,NEVER take this old stuff apart! Just clean it up in situ if possible. I have many bikes fom the 60's 70's and 80's. Their equipment does not like to be disturbed!! – user4782 Aug 15 '12 at 13:18

These are the alloy versions of the 'Sachs Huret' steel efforts of that period and I am familiar with the tension problems that can happen if you take them apart and put them back together again.

You undid the lower Allen key bolt, didn't you?

You need to take the little bolt on the side of the cage off, then undo the lower Allen bolt, swing the cage around approximately 180 degrees, tighten up the Allen bolt making sure the spring goes in, then pull the cage round approximately 180 degree, then pop the lower cage bolt back in.

Got it?

It can be done, don't go out an buy a new one, persevere.

share|improve this answer
The tension of the lower one is good. It's the upper Allan key bolt I'm worried about, the one that anchors the derailleur to the frame. The derailleur does snap up like it should, but with too little power. I'm confused about how to wind this spring (there is this little steel bit that goes in between the frame anchor point and the derailleur, that acts as a limit for the upper position, yet I don't know how to us that). – romeovs Jun 19 '11 at 6:44

Based on your comments in Mathew's answer, it may be that either the spring in the area has fatigued beyond useful recovery, or that it has been replaced with the spring windings turning the wrong direction.

Try reversing the spring in its housing, and if not that, then replace the spring.

share|improve this answer
If my edits aren't pointing to the answer with the comments you meant, please revery my edit! – Neil Fein Jun 27 '11 at 15:29
I tried this many times, all to no avail. Took the bike to a shop and got it fixed now! I still don't know what was wrong though – romeovs Jun 27 '11 at 19:46

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.