chainring size on Sb66?

[bearyeti]

HI guys, bit of help please if possible.

Just changing crank on 2013 sb66 due to me bending non drive side arm in a crash. Anyway I had to but a full new crankset as I couldn't find a non drive arm.

I've fitted new ones which are shimano xt, same as the old ones. The only difference been the outer chainring is 38 tooth whereas the old one was 34.

The problem I'm having is that even with the limit screw adjust to allow the front mech to move as far outboard as possible thee is still really bad chain rub on the mech causing quite a bit of resistance. Also the e thirteen trs chain device doesn't seem to fit round the larger chainring as well as it did on the 34 tooth.

I suppose I could just put the 34t onto the new cranks but wanted to try the 38. Am I being silly and missing something obvious I wonder. I realise the chain is probably a bit short now so most likely going to need a new one if I find a way of sticking with the 38.

Cheers in advance for any input.

[rocketmagnet]

Do you have the correct number of spacers in the Bottom Bracket?.. With XT I'd guess it will be 1 spacer on the drive side only NOTE:
if your using a BB mounted chain device the it will count as a spacer. If your using the ISCG mount then that doesn't.
With a bigger ring you'll probably need to increase the height of your Front Derail or it will rub on the narrower section at the top of the front derail.

Release the front gear cable and see if you can push the derail out far enough by hand.. if you can then your cable tension was too low... drop it into its lowest gear .. pull the cable tight and tighten on the cable. You'll have to reset your high limit again.

Also with a bigger front chain ring you'll probably need a longer chain, so if you've not changed it then your chain is probably a bit too short. To set the length put the new chain around the biggest front ring and largest back cog missing out the rear derail
then it will be 1 or 2 links overlap (see you rear derail instruction sheets for exactly how many). Cut to length and feed it through.. correctly.

Don't know the exact chain device but generally E13 TRS chain devices have a ring size range.. often 32-36 and 36-40 etc, sounds like
yours is 32-36 so it wont fit a 38T chain ring... you'll obviously need the 36-40 ranged device.

Summary.
1. Bottom Bracket Spacers
2. Derailleur Height (You'll need to release the front derailleur cable then do 3)
3. Release your cable and set tension. Set/check high and low limits
4. You've got an E13 designed for 32-36 sized rings.

edit.. bit blind and missed your last line, yeah your chain is too short .. if your changing your front rings a good idea will be to change your rear cassette and get as new chain.. I would
in fact just converted to 1X10 on my SB66 and did this....

[bearyeti]

Hi thanks for the reply. I just moved the e13 around a bit on the iscg mounts and cleaned it up. I was then able to slide the bottom guide back a bit further. There is some markings on it saying it will take 38t so I seem to have sorted that now. I'm guessing the next thing to try of your suggestions, and makes sense now is to release the cable tension on the front mech.
Thanks man.

[rocketmagnet]

ahh ok mine is also adjustable for my 1X10 but sounds like yours covers your range also.. so saves some money there.