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I have a chain suck problem on my KTM Lycan. I maintain my bikes properly and replace chains when worn etc but this bike has always been a bit troublesome when changing from small to medium or from medium to small. I’m used to it and back right off and so it’s only an issue when the drivetrain is really dirty. However my girl friend is now riding it and her gear changing is a bit more brutal so this has become a real problem as the chain is pulled up past the chainstay which seems impossible since the only way to get it back down is to pull the chainset out.
The chain was at 0.75 on the chain wear indicator so I’ve changed that and also replaced the small and medium chainrings despite them showing few signs of wear. It still chain sucks if there’s any load on while changing.
Any suggestions on what else to try, apart from getting a new gf? 🙂
jockey wheels and/or hanger alignment
I'll try another rear mech but I can't see how this could be the problem.
The first thing I'd suggest is to get the BB shell checked. Sounds like its not square to the rest of the bike. It could also be mech hanger and / or mech.
I've run drivetrains until they're completely dead on lots of bikes and chainsuck hasn't been something that gets worse with wear (for me anyway).
I just had a squizz on bikeradar and found this:
There’s reasonable tyre space, clean cable routing and conventional bottle placement. [b]The dropped driveside chainstay can cause chainsuck though, so keep the chain lubed and loved.[/b]
Hmm. I wonder if adding tension at the rear mech via the B-screw would help? Worth a go before alignment fettling as it's so easy to do, just keep track of how many turns you add!
also check for buuuurrs on the chainrings, it doesn't take much..
I always get chainsuck on new drives for the first few weeks (if its really muddy) - then it goes away
Have you checked your chainline? For some bizarre reason, I've found that replacing crankset's and BB can alter the chainline by a couple of mm and spacer arrangement rectifies.
This isn't a cure, but you can reduce the impact of chainsuck... My Hemlock's not got a chainsuck problem but it used to be that on the occasions that it did suck, the chain got horribly jammed against the swingarm, like you decribe. Solution was a blackspire stinger backplate- I've since removed the roller but the plate's still on there as it stops the chain from getting into the gap where it used to stick.
[i]the chain is pulled up past the chainstay which seems impossible since the only way to get it back down is to pull the chainset out[/i]
I'm guessing it may appear impossible when the bike is unloaded and rear suspension is at rest - like it normally would be when you're trying to fix it. When the rear suspension is compressed - even just at normal riding sag levels - you may find that it's a perfectly possible place for the chain to end up.
Thanks for all the suggestions.
Looking at the chainline, the chainset needs to move towards the frame to better align itself with the rear cassette. I think taking a BB spacer out would bring the chain rings and crank too close to the swing arm though. I'll maybe have to go with a used Stinger backplate option as I was going to try tie wraps but there's a swingarm cross bar in the way.
You need to measure the chainline. If you're running a triple chainset, the measurement from the middle of the seat tube to the inside edge of the middle ring needs to be 47.5 - 50mm.
I can't remember the dim for double or single chain ring set up's, sorry. Shelton Brown has it if you do a search on his site.
The Lycan is a nice bike too. 26 or 27.5?
Shadow + mech as a cure for chainsuck?
in the same vibe as the post above, take off the outer 40+tooth chainring (run it as a double), and shorten the chain so it's tight - tension from the rear mech may help...
Use it as a excuse for you to have your bike back and she can buy herself a new one. Everyone's a winner. 
slackalice, thanks, I'll check that measurement.
It's a 26" wheel Lycan. It's the actual test bike used by WMB magazine. I bought it from the importer at that time. I've never seen another one in the uk but apparently they get rave reviews in europe. It's not a light bike but it feels very solid and is great fun to ride. The rear suspension, a proper Horst link set up, is the best I've ever ridden.