Bicycle Mechanics - rear derailler spring tension
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Hi, I've been reading and posting some here lately, and I need to know if the small screw on the back of a Deore rear derailler adjusts the spring tension. I turned it in pretty far and I'm not sure what it does, but it looks like it moves the whole derailler backwards. What I want to do is get less chain slap on the chain stay and I thought this might tighten up and put more tension on the chain. :confused:
06-17-03, 12:11 AM
That one adjusts the tension of the upper pivot spring, and counterbalances the spring that tensions the lower arm (the lower arm has the derailleur pulleys on it). Boosting its tension should increase the chain tension slightly, but its primary function is to rotate the derailleur back far enough to keep the top derailleur pulley from reaching through the chain links and going "bump-bump-bump" against the teeth of your largest cog.
06-17-03, 09:01 AM
You can increase the tension on the cage, but as mentioned above, the lower spring opposes the upper spring. See Derailleur Overhaul (http://www.parktool.com/repair_help/howfix_deroh.shtml)
After changing spring holes in the lower cage, you will need to tighten the upper screw (B-screw). If the upper pulley rubs, you will need to go back to the original set up.
thanks Calvin and mechBgon. I changed the spring hole tonite and got it all put back together, also shortened my chain by a couple of links. The pulley clears OK so I think it will work. It feels stiffer, but I won't know till tomorrow when I get a chance to do my local trails. Ain't working on bikes fun!
You could always add a chain tensioner there are many to choose from, The Kore chain reactor is the least expensive of all of them and looks less of a DH mod than the rest.
Its quiet a bit quieter now, actually noise free going off curbs and small stuff. Thanks again.
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