Single speed using rear derailleur?

jimbog

Senior Retro Guru
Can you use a rear derailleur as a chain tensioner on a single speed build? Anybody done it before and did you get any problems? What about alignment?

Would rather buy and fit a DX item if possible, that way if me and ss don't get on I can use the derailleur to convert to geared
 
Sure, dont see why not. Use limit screws to set alignment. Some tensioners are just 'tone down' mechs anyway.
 
The other neat trick to align it is to fit a stub of gear cable - you need about 50mm. Thread it into the adjuster with the nipple through a small washer, then clamp. Turning the adjuster will allow you to tweak the mech.
 
hamster":2dnlx3bj said:
The other neat trick to align it is to fit a stub of gear cable - you need about 50mm. Thread it into the adjuster with the nipple through a small washer, then clamp. Turning the adjuster will allow you to tweak the mech.

nice tip :)
 
only trouble doing that is the tension is only one way (when your pedaling) so when you freewheel over bumps ect you will have some slack going on as the mech comes off load. think of how a mech works, you will have to have the jockey wheels pointed almost parallel to the chainstay for any effective tension which isnt ideal
crc sells tensioners from 12 quid that do the job properly
http://www.chainreactioncycles.com/SearchResults.aspx?Search=chain guides&CategoryIDs=62
 
I ran a short cage mech as a tensioner for a while. It was a sucess. Then I took it off and now it has no tensioner.

The china does not get chance to jump of if you keep pedaling and the chainline if perfect.
 
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