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Recently bought a used tandem.
Got old at 9speed mtb gears.
Recently got new dropouts welded in as the old one was cracked. This made the chainstay 5mm shorter they said. So maybe something to do with slack in the chain now?
Since putting the rear mech back on the jockey wheel is touching the chain/cassette.
Turning the b screw doesn't seem to be doing anything.
I've tried screwing it in or out with the mech disconnected too.
If I screw all the way in it doesn't catch on all but the 2 lowest gears.
Any ideas?
Sounds like they've changed the angle the stop on the gear hanger sits at.
If I screw all the way in it doesn’t catch on all but the 2 lowest gears.
Would a [url= https://www.sigmasports.com/item/Wolf-Tooth-Components/25-mm-B-screw/I9ZD?utm_source=google&utm_medium=base&utm_campaign=base&co=GBR&cu=GBP&glCountry=GB&id=852745&gclid=CjwKCAiAqaTjBRAdEiwAOdx9xtwcgfgPsFPh6MAHnEr8mORkvdd0Bq_WqY8isyHSsJHNLQrqIoXCwBoC_L0QAvD_BwE&gclsrc=aw.ds ]longer B screw[/url] work (it sounds like it's pushing against something)?
I think it could be chain slight to big now.
Did you check the chain length with the new shorter chainstays?
The B tension adjustment is not for taking up chain slack, it is for setting the correct gap between the upper jockey wheel and the cassette.
No not checked it, only remembered about it now having a shorter chainstay while posting on here.
To be honest I only ever noticed the B Screw really having an impact on gear set up once i went 11 speed.
Length looks ok. With the limit screw all the way in it's ok apart from the lowest gear.
Puzzled
The mech is a old deore xt. M737
I've flipped the screw which has put more tension on it and it now (just) doesn't make contact with the 32 sprocket.
Doesn't seem ideal though.
Maybe the tension spring is just getting a little old?
Random picture of dropout spec from google, you could check what the requirements for your mech are. Most normally work fine, but if you are at an extreme of mech capacity and a dropout at one end of the scale you can get issues.
RD-M737
https://si.shimano.com/pdfs/si/SI-R330C-000-00-ENG.pdf
8 speed
32t max cassette
22t max front chainring difference (20t in 2nd docs)
total capacity 38t
chain length big-big + 2links
We had a brief go on it before it's new drop outs and I can't recall any noise in the 32.
Sounds like it's the new drop outs.
They had to put Ritchey dropouts in as they couldn't source the original dropouts.
Any negatives of having the screw flipped.
Could buy a longer screw. (Any negatives to putting so much tension through it)
If you pull down manually on the mech. manually, is there enough movement in it to clear the big cog? If there is I still wonder whether a longer B screw would nudge it down enough to clear the cassette.
One the screw is too long it can end up going past the tab on the mech hanger (depends on the mech hanger), fitting the screw upside down can help it catch the mech hanger tab if you just need to squeeze a bit more out.
Other random thought, the outer cable length is not pushing or pulling the mech excessively?
Have you tried spraying it with GT85?
Good one.haha