[RPtheFP]

I run a 1x9 set up and just bought some used Noir 3.3 cranks that I took the large ring and granny gear off. I also bought a MRP 1.x to replace my front derailleur as a chain guide. The issue comes when I went to install the guide with the cranks. I cannot get the chain to not rub on the inside of the guide when in the large gear in the back.

Is this a compatibility issue (the MRP site says it works with the Noir cranks with a 68 mm BB) or does the Noir crank have an unusual chain line? The chain seems to want to jump down a gear because of the angle of it.

I have been frustrated with this and am tempted to just get a Paul Chain Keeper. The MRP does not have much adjustment laterally short of grinding it down.

 

[tate6969]

do you have any spacers on the drive side of the bottom bracket?

 

[RPtheFP]

do you have any spacers on the drive side of the bottom bracket?

No I do not. If I did the chain line would be way too far off. If anything I need to get it towards the inside of the bike more.

 

[rockyuphill]

Noir cranks have a 51mm chainline rather than Shimano's already wide 50mm, so there's the rub. I get a trace of rub on the inside using the MRP with a 32T front and a 34T rear with XTR cranks.

 

[tate6969]

im the same with XT cranks, a trace a rub when in the big cog.
no spacers.

 

[SOLOMON's]

I just installed mine, got bit of rubbing, but my mechanic told me is inevitable.

 

[standard3x]

Place a 1mm or 1.5mm spacer on the non-drive side (NDS) to pull the drive side (DS) crank inboard by that amount to eliminate the rubbing and to prevent the chain from dropping down to a smaller sprocket from the 34t sprocket when you back pedal.

As some may be aware, the NDS cup has an internal reducer "bushing" ring that locks the tapered GXP spindle into place leaving a gap between the DS cup and the DS crank ie the crank does not sit flush onto the surface of the bearing cup. This gap is approx 2.5mm wide. This is why you are able to pull the DS crank inboard by adding spacers onto the NDS.

The OP actually requires a different solution: shim the cassette outboard by about 1mm to 1.5mm (don't worry there will be enough thread on the cassette lockring and probably enough chainstay clearance for you to do this).

Edit: I forgot to mention that you can get the spacers from K series (chaincase compatible) square tapered BBs (I have loads of these spare so know that they work) OR you can make them from a length of steel wire (a big paperclip also works).

 

[SOLOMON's]

Just sharing what I've learned today, after installation, shift to middle cog (E.g. if you are using 9 speed, it will be 5th cog) of the cassette.

Check whether the chain is aligned to the center (where the 2 pcs of plastic meet).

Play around with spacers/washers.



NOTE: DON'T OVER TIGHTEN THE HEX BOLT, MINE BECOMES A ROUND BOLT NOW. THE MATERIAL IS VERY SOFT!

 

[scrublover]

Or, the easy solution: tweak the 1.x mount arm just a touch, to get no rubbing.

Or add a bit of washer between the plastic bits, at the rear bolt holding things together, to spread the back end of the guide apart a bit.

 

[SOLOMON's]

Or add a bit of washer between the plastic bits, at the rear bolt holding things together, to spread the back end of the guide apart a bit.

True! But just keep in mind too much clearance the chain got higher chance of JUMPING OUT!

I did some shifting and I pedal backwards (Hell knows what I'm doing!), my chain get into the BB side, it's heart wrenching and balls squeezing too see the plastic being bent when putting the chain back!

 

[RPtheFP]

I got is solved but I had to do some custom work on the guide. I may post pics in the 29er forum.

 

[RPtheFP]

Custom MRP 1.X

Problem Solved

 

[Dan Gerous]

Nice setup! I'm waiting for the clamp-on version of the 1.X but it's not out yet, might be tempted to DIY myself something...

 

[half_squid]

Is that a braze on front derailer adapter? I know nothing about roadie anything. I've thought rigging up a clamp on mount since MRP is dragging their feet on 1.X Clamp On production and you can get the G2 Mini Upper Plastic part as a spare for about $20. Details man!

 

[RPtheFP]

Yeah that is a braze-on adapter. Sorry for the delay in the post. Just measure the diameter of your seat tube and BAM, problem solved.

 

[Trent R.]

sorry to bump this so late.... does everyone running a bottom bracket mount chainguide, like the 1.x, have an extrenal bearing bottom bracket? or can it be run with a regular bottom bracket like the shimano es-25?