Having problems with the derailleur in an old Panasonic 10 speed.

When I shift the bike all the way up to 5th gear ( smallest in the back) the spring on the hanger of the derailleur has no tension at all causing the bottom of derailleur to ride the chain.

I don't know if I have the right chain or not because I found the bike abandoned on the street. Any advice would be appreciated.

  • 1
    Pretty hard to say, without being able to examine the bike. Could be the derailer just needs a good cleaning, could be the chain is stretched, could simply be that the wheel is not all the way back in the dropout slots. Oct 8, 2017 at 22:34
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    If you found the bike on the street then it likely needs a full service.
    – paparazzo
    Oct 8, 2017 at 23:03
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    If there's no spring tension on the rear derailleur when in the smallest cog, its probably weak with age. Standard fix would replace the rear mech with something newer. There's little point trying to fix the spring.
    – Criggie
    Oct 9, 2017 at 4:15
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    Be sure to check BikeIndex.org or another serial number / stolen bike registry. Often "bikes found on the street" were stolen and then abandoned. You'll get karma points if you can return it to the rightful owner.
    – RoboKaren
    Nov 8, 2017 at 20:37

1 Answer 1


This can be down to a few things, and without inspecting it, can only speculate.

First thing is to set the gears to the largest on the back and the largest on the front. If the chain is too tight and the rear derailleur is pulled right down, then it is bad selection of parts. Mismatched parts is a cheep or bad design.

If tension is okay, then you can try removing a few links from the chain. It might be that the chain was not correctly fitted if it was a replacement part.

Might be the wrong derailleur for the bike and a smaller one would be better suited.

But all is just speculation. If you let us know, we might be able to narrow it down.

  • I will be going out later to get a newer derailleur and hope that will correct it but I have a feeling the chain may need to be replaced or shortened, Oct 9, 2017 at 8:02

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