Recently bought a Duo chainset and Royce bottom bracket.Set it up with XT front mech.Shifting very tempermental.Dropped the height of the mech and played around and all was well.Went to ride a local race last night and disaster! Severe chainsuck,so much so the chain had double wrapped round the top of the chainring and jammed in front mech.Managed to get it running and it didn’t feel right.Pulled out of race.Rode home and perfect shifting! What’s your set ups with these cranks.Mech’s,bottom brackets,chains? Give me hope as i think i’am going back to my XT Hollowtech!
Thanx Max

are you running 29:42 ?

i had this issue with XTR mech and the duo. First thing i did was run the mech “slightly” higher than you would with a standard 44 tooth ring as in 1/2mm

then i gave the mech a slight bend to match the curvature of the ring (youll notice the mech tracks the curvature of a 44tooth ring)

this solved all my issues

is the chain/rings new ? its rare for a mech to cause suck :s

113mm UN73 But I ended up switching to a Sram front mech to sort my shifting. Chain suck shouldn’t happen with the right chain line new chain/chainrings(?)

The Sram mech has a much ‘shallower’ inner plate so clears the 29 ring better than an XTR – I thought about cutting the XTR plate down – but I’ve been conditioned its sacred.

I had endless chainsuck problems with my ‘burn triple setup on the granny ring, using standard Middleburn rings. The chainsuck problems only stopped when I turned the granny ring round and ran it ‘back to front’.

Does this mean that there will soon be some cheap Middleburns on eBay? 🙂

Never had a problem while I was usuing a Duo set up, 29/42. I was using an XTR front mech and had the chainset from new, with new rings.

Now using the same mech with a Middleburn Triple set up, 24,32 44 and still having no problems with Chainsuck.

Was the chain you fitted new ? Maybe an old chain could have been a contributory factor ?

29-42 here, same problem. Every now and then when dropping from top to middle, the chain will snag and drag itself round, only way to remedy it is to backpedal and try again, but usually end up stopping and sorting it.

Chain suck is nothing to do with the mech. Usually it’s caused by a worn chain on newer chainrings or by a very worn and hooked chainring. How used is your chain?

I had trouble recently. Brand new slickshift hardcaot rings, new chain, new cassette (new shifters and rear mech not that they make any difference) and an old Raceface crank and XTR front mech. It was unridable due to chainsuck. In fact, it was worse than the worn Blackspire kit that was coming off the bike.

Hi,
Yeah, chainset is brand new and chain is only 2 or 3 rides in.Its running the 42/29 double with a 103 mm bottom bracket(reccommended by Royce).Thinking the rapidfire may not help,a friction shift either thumbie or gripshift might be the answer? Ran a Middleburn triple a few years back with an XT thumbie with no trouble.
Thanx Max

How can the shifter be the issue? Chain suck is caused by the chain not releasing the chainring. The mech could conceivably be to blame if it somehow interfered with the chain but what could the shifter do?

I just thought the shifter being indexed doesn’t help.With a friction shift your not reliant on the indexing.A botched shift can cause chainsuck,like changing gears under pressure.I used a variety of rings on an old crosser and used an old bar end shifter.Perfect shifting! But that could be cause i was lucky that time!
Thanx Max

Last duo cranks I ran were some Coda Experts. **** brill but only if used with TA Specialite rings (29,42). I think I was also running a Ringle antisuck plate as well.

What are the chainrings and the chain? There’s a problem with compatability here. Middleburn rings tend to be on the wide, chunky side, so prone to not “letting go” of the chain. Rings should all work 8 or 9 speed (guess you’re running 9 speed?), so 9 speed chain should be fine; double check you’ve not got a 10 speed chain by mistake! My first action would be to try a different brand of chain,and if that fails, go for some different rings, TA, as someone else mentioned, are very good. Cheaper option would be BBB, not a well known name, but great product for the money. Give it a few more rides first though, it may settle down. New CNCd rings can have very sharp square edges which take a while to mellow out. Good luck!

what bike is it? I’ve always run my duo with a 113 bb on every frame its been on (2 konas, a cove handjob, a 456 and a cotic soul) and its only ever sucked when the chainring is worn out.