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Help with rear derailleur adjustment
Hello all,
Question with rear derailleurs. I know I shouldn't really be using this gearing combination but when I have the chain on the smallest front chainring and smallest rear cog, there is no tension on the chain. This is causing the chain to jump off the bottom jockey wheel. It started to happen after I changed the bottom jockey wheel.
Is there any way that I can adjust the rear derailleur to increase tension on the chain with this gear combo? How do I go about doing this? My derailleur is a shimano SLX. The rest of the gears changes fine.
Thanks
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Did you get the correct jockey wheel? You didn't replace an 11 tooth with a smaller 10 tooth which would give the chain more slack? You could take a couple of links out of the chain.
Screw in the screw near the hanger.
long shot - have you had the deraileur off the bike? If you re a numpty like me, i managed to get the deraileur on the hanger wrong, secondly, i also managed to have the chain run the wrong side of the steel bit between the jockey wheels - caused no end of trying to figure out why it wasnt working smoothly. sometimes its the real obvious stuff.....
You sure you got correct jockey wheel? If no probs before the change then likely to be the changed item. So check you got the correct one.
You may also want to check the derailleur is straight.
Assuming it is a 3*10(or 9) then granny and small rear cog (small small) is usually 'out of bounds'. If 2*10 then it should be usable. There are a number of things you can do but depends on total system components.
so do you have:
2*10; 3*10, 3*9?
what are the front ring sizes 22x33x44 (stock) or different?
what is smallest and largest rear cog, 11 and 32 or 36?
is chain standard length (and how old)?
Long or medium cage rear?
How is the chain tension on small x 2nd small?
Does chain still have bend in it around the Der. in Large large (if you use that combo)?
You can adjust the B screw to put on more chain tension, but if you also use large x large then you may damage your rear derailleur if tension it for small small combo, so check you can use the large large combo.
Assuming you have a stock 3x9 or 10 system and chain is correct length and not too worn, then adjust B screw so chain slack is reduced to minimum. But check that gear changing doesn't deteriorate too much as the more B screw the less accurate the change. The B screw moves the top jockey wheel in the derailleur arm away from the the rear cassette and tensions the chain.
HTH
PS: what was reason for changing the jockey wheel?
I replaced the bottom jockey wheel cos the teeth of the old one had worn out. I am wondering if the float of the original is what's making the difference. The new one is an alloy one off eBay. It's 11 tooth, same as before.
The system is 3 x 9, 22,33,44 with 11-34 cassette. Chain is coming to about 2 years old. Long cage dérailleur. Chain tension on granny chainring and 2nd smallest cog seems ok. I'll have a go at changing the B screw. if I physically rotate the derailleur clockwise it tensions up the chain.
Any other ideas?
replace the chain.
and replace the cassette.
and front rings