[DeoreDX]

Converting a old Stumpjumper from 3x9 Sram X.7/X.9 w/ Shimano M542 cranks to a 1x10 Advent X setup. My current chainline is in the "good" range I measured around 47-48mm. If we count the cogs on the cassette as #1 being the 48t and #10 the 11t the chain lines up with the #6 cog biased towards the smallest cogs. I have two spacers on the drive side of the BB. Since I'm a old plodder on the trails and use my big cogs more than the little cogs I'm debating if I should try removing the spacers and line the chainring up with the #5 cog. The reasoning is better chainline for the big cogs I tend to use more. Any reason not to make this change? I can pedal backwards in all of the gears with no issues right now. Will I start dropping the chain in the 11 tooth if I move the chainline in further?

 

[Reaperactual]

The standard chainline for a non Boost frame using a 2/3x set up is 44mm. Adding a 1x10 set up requires moving the chainline out by a further 2mm (recommended offset for 1x10) to 46mm for optimum chainline.

I assume you are using a Hollowtech II bb, if so those Shimano bb's should be set as one 2.5mm spacer on each side of a 68mm wide hub shell and only one 2.5mm driveside spacer for a 73mm wide hub shell. Maybe the spacers aren't in the correct placement now and the whole crankset could be slightly driveside offset bias already?🤔

Moving the chainline in won't make the chain fall off the 11t cog. The consequences of the chainline being in too far is the chain rubbing slightly on the next biggest cog up from the 11t one and the obvious chainring/chainstay and chain/tyre clearance in first gear.

 

[J_Westy]

Converting a old Stumpjumper from 3x9 Sram X.7/X.9 w/ Shimano M542 cranks to a 1x10 Advent X setup. My current chainline is in the "good" range I measured around 47-48mm. If we count the cogs on the cassette as #1 being the 48t and #10 the 11t the chain lines up with the #6 cog biased towards the smallest cogs. I have two spacers on the drive side of the BB. Since I'm a old plodder on the trails and use my big cogs more than the little cogs I'm debating if I should try removing the spacers and line the chainring up with the #5 cog. The reasoning is better chainline for the big cogs I tend to use more. Any reason not to make this change? I can pedal backwards in all of the gears with no issues right now. Will I start dropping the chain in the 11 tooth if I move the chainline in further?

Are you having any issues with your set up? It sounds bang on to me?

I always recommend referring to this article that says 47mm for non-boost 10-speed.

Boost Chainline and 1x Boost Chainring Selection

Boost Chainrings, Chainline and 1x Boost Chainring - science, explanation, and selection.

www.wolftoothcomponents.com

 

[Reaperactual]

Are you having any issues with your set up? It sounds bang on to me?

I always recommend referring to this article that says 47mm for non-boost 10-speed.

Boost Chainline and 1x Boost Chainring Selection

Boost Chainrings, Chainline and 1x Boost Chainring - science, explanation, and selection.

www.wolftoothcomponents.com

Same Wolftooth article that I'm quoting from and I swear by it too that says at least 2mm at 46-47 for an optimum chainline.

I went 46mm you went 47mm. 😎👌

The chainline sounds good but the two spacers on driveside doesn't seem right and if changed it's gonna be 45-46 so is it worth adding 1mm crank bolt spacers or leave it where it will end up?

 

[DeoreDX]

Are you having any issues with your set up? It sounds bang on to me?

I always recommend referring to this article that says 47mm for non-boost 10-speed.

Nope but I just installed it and haven't given it a proper run in the dirt yet. Once you start bouncing around and get things dirty sometimes the drivetrain can act a bit different when when it's on the work stand.

 

[DeoreDX]

Same Wolftooth article that I'm quoting from and I swear by it too that says at least 2mm at 46-47 for an optimum chainline.

I went 46mm you went 47mm. ??

The chainline sounds good but the two spacers on driveside doesn't seem right?

I just realized I forgot to add the chainring thickness into calculating my chainline. I had measured to the inside surface of the chainring at 47.5mm. The chainring is ~4mm thick. So to the middle of the chainring is 49.5mm. Looks like I need to move at least one of the spacers over for proper chainline.

When you look at the bike with the 3x chainrings the big ring was incredibly close to the chainstays. I'm guessing they spaced it out to one side to help with the big rung rubbing on the chainstay.

 

[Reaperactual]

That makes sense, wow and that's still a bit too close for comfort Pal!😬

I reckon 1x was a good move before that chainring ate your frame.🤣

 

[J_Westy]

I went 46mm you went 47mm. 😎👌

plus more if you have fat tires or big chainrings that are too close to the chainstays... which is where the "standard" 49mm comes from.

I dig what Garbaruk does on their direct-mount chainrings by putting more offset the smaller the chainring.

 

[Reaperactual]

So glad I've got 2.4 tyres and loads of chainring clearance to fit a new 32t chainring, 49mm crank chainline instead of the 30t at 51mm my bike came factory fitted with? Wolftooth know about chainlines, sounds like Garbaruk do too at least. 😎👍

#gettingitsorted

 

[DeoreDX]

My bike had two spacers but they were the thin spacers not the 2.5mm spacers and they totaled 2.5mm.

I used the googles and looked up my cranks (M542) and read up the shimano installation guide for the cranks. Amazing what information you get when you RTFM.

With my 73mm bottom bracket they recommend a single 2.5mm spacer on the drive side and that will give you a 50mm chainline. That fits since I measured 49.5mm and had 2.5mm of spacers on the drive side.

Since I need at least one spacer to fit the BB I'm going to put a single 2.5mm spacer on the non-drive side which should give me a nice ~47mm chain line. Using a straight edge it looks like that puts me somewhere near the middle of the cassette instead of slightly biased towards the small ring.