richardkzn Posted November 11, 2015 Share Erm, no. It'd be the same. Your chain's point of engagement (just slightly rearwards of top dead centre on the chainring and slightly forwards of TDC on the cog) doesn't change when you change chainring & cassette sizes. Nor do your chainstays miraculously shorten as soon as you go to a 1x setup... so - your distance between the top of the cassette and the top of the chainring is static. It's the chainline that determines just how kinked the chain becomes at each extreme - not your chainring & cassette sizes.Yes I agree, but when you have a 34t chain gear and 42t rear your chain stays longer on the 42t making the angle bigger to your chain gear. Not making the chain shorter. If you are looking at the chain from the top. Maybe i' m not explaining properly what i'm trying to say. Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted November 11, 2015 Share Yes I agree, but when you have a 34t chain gear and 42t rear your chain stays longer on the 42t making the angle bigger to your chain gear. Not making the chain shorter. If you are looking at the chain from the top. Maybe i' m not explaining properly what i'm trying to say.Maybe for like an extra 5mm, but that wouldn't make a substantial difference to the angle at which the chain sets off. Link to comment Share on other sites More sharing options...
NicoBoshoff Posted November 11, 2015 Share Just remember that an 11sp cassette is slightly wider at the cogs than a 10sp (measured 11t to 42t on the outside) It's the same width on the free body area (where it mounts to the freehub) but the 10sp 36t granny is "flat" whereas the Shimano 42t is mounted inboard on the spider, and the SRAM 42t is concave, so that may be creating the chainline issue - the 11sp granny gear is closer to the spokes than the 10sp granny. This is also why you need to either mod a 10sp road freehub, r get a new road freehub, to allow a road bike to have an 11sp cassette - the granny just can't get enough concavity and still stay clear of the spokes. Will try to find a picture when I'm at my desk Here you go - back of a PG1080 cassette. 36t mounts to the freehub body (42t range extender fills the same spot) and is flat. http://cdn.media.cyclingnews.com/2010/06/14/1/sram_xg_1080_alloy_600.jpg Shimano 11sp XT showing 42t mounted to the spider, not extending to the freehub. Also marginally concave. http://flowmountainbike.com/wp-content/uploads/2015/04/XT-11-speed-5.jpg XX1 cassette showing 42t concavity http://twentynineinches.com/wp-content/uploads/2013/12/5-SRAM-X01-cog.jpgOk, I'm getting spacers. Shot. Link to comment Share on other sites More sharing options...
richardkzn Posted November 11, 2015 Share I wonder if this 1 x 11 is a good idea, poor chain must take a lot of strain. Link to comment Share on other sites More sharing options...
Captain Fastbastard Mayhem Posted November 11, 2015 Share I wonder if this 1 x 11 is a good idea, poor chain must take a lot of strain.Chain is a consumable item... And, it's showing the same general KM tally as other systems, with proper maintenance. Link to comment Share on other sites More sharing options...
JXV Posted November 11, 2015 Share Yes I agree, but when you have a 34t chain gear and 42t rear your chain stays longer on the 42t making the angle bigger to your chain gear. Not making the chain shorter. If you are looking at the chain from the top. Maybe i' m not explaining properly what i'm trying to say.Yes but at the same time your 34 chainring is smaller than the 38t or 40t that was there before and it is mounted inboard on the spider. There are so many combinations possible, what with gear size choices, different BBs, cranks, chainstay lengths and now even some bikes designed with different chainlines. OP ( Lance) ..... what cranks do you have. This might help. Exact model if you can. Tks......or some pics. Link to comment Share on other sites More sharing options...
Kiwi Posted November 11, 2015 Share One other thing you could check is the distance between the top jockey wheel of the rear derailleur and the 42. You may need to move them further apart by adjusting the B screw. Link to comment Share on other sites More sharing options...
Lance Roberts Posted November 11, 2015 Share Yes but at the same time your 34 chainring is smaller than the 38t or 40t that was there before and it is mounted inboard on the spider. There are so many combinations possible, what with gear size choices, different BBs, cranks, chainstay lengths and now even some bikes designed with different chainlines. OP ( Lance) ..... what cranks do you have. This might help. Exact model if you can. Tks......or some pics. The bike is a 2015 Scott Spark 910, crank is a previous model XT 2x (Think its M875), chainring is a Absolute Black 32t oval, cassette is a 11 - 42. Unfortunately I don't have any pics, I changed everything back to my previous setup so that I can get some training in for the weekends race. Link to comment Share on other sites More sharing options...
Lance Roberts Posted November 11, 2015 Share One other thing you could check is the distance between the top jockey wheel of the rear derailleur and the 42. You may need to move them further apart by adjusting the B screw. Thanks, that's the first thing I did and it looks pretty good, approximately 5mm away, as mentioned in the manual :-) Link to comment Share on other sites More sharing options...
raptor-22 Posted November 11, 2015 Share chain wrap on the sprockets is a big problem. With a 1x system the reduced chain wrapon the driver ring (crankset) is important to chain retention. Its the reason why 1x systems have a different tooth profile. I tried a majat 1x system as well. Had problems with chain retenion in extreme gears when back pedalling. Chain just seems to hook the recedeing tooth badly and derails. Having gone proper 1 x the problem is gone, mostly because of the different tooth profiles relieving the chain pressure on the teeth Link to comment Share on other sites More sharing options...
Lance Roberts Posted November 11, 2015 Share chain wrap on the sprockets is a big problem. With a 1x system the reduced chain wrapon the driver ring (crankset) is important to chain retention. Its the reason why 1x systems have a different tooth profile. I tried a majat 1x system as well. Had problems with chain retenion in extreme gears when back pedalling. Chain just seems to hook the recedeing tooth badly and derails. Having gone proper 1 x the problem is gone, mostly because of the different tooth profiles relieving the chain pressure on the teethSorry but when you say "proper 1x" what do you mean? Link to comment Share on other sites More sharing options...
raptor-22 Posted November 11, 2015 Share Drivetrain with a single chain ring designe to work as a single chain ring. Higher tooth profile, wide narrow wide teeth, zero shift ramps Link to comment Share on other sites More sharing options...
JXV Posted November 11, 2015 Share The bike is a 2015 Scott Spark 910, crank is a previous model XT 2x (Think its M875), chainring is a Absolute Black 32t oval, cassette is a 11 - 42. Unfortunately I don't have any pics, I changed everything back to my previous setup so that I can get some training in for the weekends race.Ok M785 XT 2x crank. Exact same as mine. (M875 dne) So there should not be any funny offsets or anything. I will check Shimano website to see if that crank is made with different offsets. I can only think, as Myles said, that the big cog on that 11spd cassette is causing the issue 'cos its mounted further inboard than the 10spd version. With your pressfit bb you sure there are no spacers at all between bb and frame or between bb and crank arm? Link to comment Share on other sites More sharing options...
bergy Posted November 11, 2015 Share go to a hardware store,buy 10mm spring washers,+/- R 10.00 a pack and fit them between the spider and chainring,and then re check your chain line,if it looks better than buy the spacers,or just leave the spring washers in place,they also keep tension and stop the chainring bolts from coming loose.the washers are generally 2mm thick Link to comment Share on other sites More sharing options...
Lance Roberts Posted November 11, 2015 Share Ok M785 XT 2x crank. Exact same as mine. (M875 dne) So there should not be any funny offsets or anything. I will check Shimano website to see if that crank is made with different offsets.I can only think, as Myles said, that the big cog on that 11spd cassette is causing the issue 'cos its mounted further inboard than the 10spd version.With your pressfit bb you sure there are no spacers at all between bb and frame or between bb and crank arm?I'll have to double check, but I did not see one. And even if there is one, I wouldn't want to take it out, don't want to stuff around with the original setup of the bike in that way. I'll check for spacers. On the 1x crank side of things, there are none available in the country as far as I can see. Been on the phone to almost all of the online stores and some LBSs.. Gonna have to stick to my 2x crank setup for now, with 10sp in the back. Thanks for all the positive feedback guys, really appreciate it! Does anyone know the chain line figures for a 2x crank? Is the 1x crank an "in between" measurement? Link to comment Share on other sites More sharing options...
Attie Lourens Posted November 11, 2015 Share I had the same problem so decided to make my own chainrings with integrated spacers and thread. Works like a bomb. I have since made up a couple more that is being anodized at the moment. Pls pm me should you be interested. Link to comment Share on other sites More sharing options...
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