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Ok tried everything and no joy. Here is what I have. Sorry for the long post.
Mondraker Foxy 2016 2x10 shimano setup. Front mech is deore, shifters are SLX. SRAM crank with truvativ rings. Mech is a top pull, mounts to a bracket that mounts onto back of seat tube.
In smallest chain ring and biggest sprocket mech set till it just touches chain then barrel backed off half a turn so no rubbing.
When shifted into big chain ring and smallest sprocket the mech cage rubs a lot on chain pushing it quite a way back into frame. It doesn't stop rubbing until the rear is on the third biggest sprocket.
Limit screws aren't stopping the mech and if I push and hold the shifter the mech moves clear.
It seems that the shifter simply doesn't pull enough cable through. Cables are new enough and all pull smoothly and mech is clean and no movement issues there. Can it be the crank/spacing between the rings?
Final point, the bike came with SRAM shifters and rear mech but I didn't like them and felt the front SRAM shifter didn't work well with shimano mech. Prefer shimano so swapped rear mech and shifters to shimano. Still no joy. Although much happier with rear mech performance!
Any help or thoughts or experience greatly appreciated.
Cheers
Cam
I've had this problem on a lot of 2x Mondrakers, especially the Sram shiftered versions, as they don't seem to pull quite enough cable. The best i've come up with is to run the shifter as a 3x as the first shift seems to pull a touch more cable than the second, and do final setting up whilst test riding, rather than on a workstand, as sag makes a difference to where the chain sits in relation to the mech cage (edit- seem to remember that you can run a bit more lower limit, and thus a bit less cable slack once sag comes into play) . Sorry I can't be more helpful re positioning of the mech, and cable tensioning, but it's been a couple of months since I had the joy of setting one up.
You say you've backed off the barrel adjuster in the smaller chainring to stop it rubbing - you shouldn't be needing to alter the cable tension there.
Disconnect the shifter cable and set the small chainring/large sprocket position using only the limit screw. Wind the shifter barrel adjuster all the way in, then a turn or so out. Reattach the cable to the mech, with only light hand tension. Shift into the bigger chainring and run through the cassette, adjusting the barrel adjuster for the front mech so as to obtain the least rub at either end of the cassette. Finally, set the other limit screw to prevent over-shifting. Job done.
Set originally as you say. Used lower limit screw attached cable and it barely shifts into big chain ring. Any slack in cable needs taking in first, so I took up slack with barrel adjuster so it shiifts into big ring.
As I said it is though the shifter doesn't pull enough cable through therefore if there is any slack in cable at all it makes it worse, hence using the barrel adjuster to take up the slack first then backing off so it doesn't rub. Leaving it in the position the lower limit screw would effectively hold it in without the cable tension.
Coatesy do you use 1st and 2nd on the shifter or 2nd and 3rd? I was hoping shimano shifter and mech would sort issue.
Annoyingly I don't have any mates who run 2x to look how their mechs run etc.
Please excuse the question - but are you sure you've run the cable correctly around the front mech?
I seem to remember having a similar issue with a front mech & it turned out there was a little notch on the mech that the cable was supposed to go over that meant it passed over a raised 'cam' type feature; this gave it the correct amount of cable pull. When it was routed incorrectly, it didn't look obviously wrong & pulled a fair amount of cable; just not quite enough.
Worth double checking anyway...
^^^^^^
Forgot about that - been so long since I looked at a front mech!
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Use 1st to 2nd shift (setting it as 2x removes this shift option, only allowing 2nd to 3rd), high limit screw should prevent it going into 3rd.
Main reason I went 1x was I hated front mech faff. 2x especially.
Just a thought but the entry angle/height of the chain changes with sag and compression doesn't it.
The mech cage is wider in some parts than others (iirc the tail/rear end of the cage is narrower particularly on the inside edge).
If the chain enters the mech higher / further forward when sagged then it may cure the rub.
It's been a while since I set up a mech from the box on an fs bike but I recall my ancient 2003 Enduro was prone to rubbing at standstill.
^^ Pretty much as I pointed out earlier, you'll struggle to get it right without riding it too.
Well! Coatesy you sir are a genius!
Had a fiddle tonight flicked to 3x mode on shifter doubled checked limit screws reset cable and it's sweet as a nut. Went for a quick spin and it's perfect!
Cheers for the advice everyone.
Also I will go 1x at some point but I'm unfit and broke so current setup works better!