Chainline with XT M8000 11 speed

[JXV]

Having said that I am tempted to order a new ring from Kalbo and just get the spacers included. Would my LBS have the correct length chainring bolts to accomodate the spacers?

Nico

 

On my 2x10 Shimano XT crank the standard chainring bolts were too short when the spacer washers were added. Only a few threads engaged and I was pretty sure they would break under load.

 

I bought aftermarket chainring bolts for a 3x crank which are longer. Remember, on a 3x crank the bolts are longer to accomodate middle and outer chainrings so they work nicely for the 1x chainring plus spacer.

[Captain Fastbastard Mayhem]

Hi Lance

 

I got spacer washers in the kit from Kalbo.

 

That 32t chainring pic you posted shows that it is threaded to receive the chainring bolt and has a raised 'collar'. Never seen this before.

 

What are the outer diameters of the two raised bits? For comparison the outside diameter of the female threaded collar of a normal chainring bolt is 9.85mm. So a spacer washer with i.d. of 10 mm fits over them.

 

Also....that 32t should be mounted with the raised collars facing the spider and not facing the BB. Presume you fitted it this way?

Often happens with 30t and some 32t rings to remove them slightly from the crank, cos the chain fouls with the spider if there's no spacer and the spacing is 104bcd. Threaded inserts also make it far easier to mount.

 

Doesn't happen with DM rings, of course.

[Captain Fastbastard Mayhem]

Nico

 

On my 2x10 Shimano XT crank the standard chainring bolts were too short when the spacer washers were added. Only a few threads engaged and I was pretty sure they would break under load.

 

I bought aftermarket chainring bolts for a 3x crank which are longer. Remember, on a 3x crank the bolts are longer to accomodate middle and outer chainrings so they work nicely for the 1x chainring plus spacer.

Dremel

 

If they're too long, that is

[NicoBoshoff]

Nico

 

On my 2x10 Shimano XT crank the standard chainring bolts were too short when the spacer washers were added. Only a few threads engaged and I was pretty sure they would break under load.

 

I bought aftermarket chainring bolts for a 3x crank which are longer. Remember, on a 3x crank the bolts are longer to accomodate middle and outer chainrings so they work nicely for the 1x chainring plus spacer.

Cheers.  I'm waiting to hear from Kalbo and Rapide which of them could offer the full kit (ring, spacers and bolts) since it appears they each only have two of the three available.

[Lance Roberts]

Hi Lance

 

I got spacer washers in the kit from Kalbo.

 

That 32t chainring pic you posted shows that it is threaded to receive the chainring bolt and has a raised 'collar'. Never seen this before.

 

What are the outer diameters of the two raised bits? For comparison the outside diameter of the female threaded collar of a normal chainring bolt is 9.85mm. So a spacer washer with i.d. of 10 mm fits over them.

 

The problem with fitting the spacers on my setup is that the bolt will then have nothing to centre itself within the spider. I've been looking at all the options and the spacers wont work for me. I think the 32t that I've got was done in this way to prevent the chain from touching the spider, because it's such a small diameter, which means it's already a bit further away from the spider, it's just not enough it seems.

 

Like a lot of the guys are saying, it might be because everything is new and has to wear in still, but I just think I need a little bit less angle towards the 42t.

[Captain Fastbastard Mayhem]

The problem with fitting the spacers on my setup is that the bolt will then have nothing to centre itself within the spider. I've been looking at all the options and the spacers wont work for me. I think the 32t that I've got was done in this way to prevent the chain from touching the spider, because it's such a small diameter, which means it's already a bit further away from the spider, it's just not enough it seems.

 

Like a lot of the guys are saying, it might be because everything is new and has to wear in still, but I just think I need a little bit less angle towards the 42t.

It's a bit of a hack job, but what you can do is take one of the female chainring bolts (nut, if you prefer) and cut that down to act as your spacer. Just remember to allow enough extra to fit inside the bolt hole on your crank.

[NicoBoshoff]

Just got some feedback from a supplier.  Reckons on a 2x10 crank you should be ok without spacers because spider already more inboard than 3x10.

As I said, the chainline hasn't been an obvious issue for me on my 1x10 setup and I'm not increasing the angle between ring and cog given same width casettes.

[NicoBoshoff]

P.S. My XT shifter and Zee RD (short cage qith 11-36t range) will be for sale soon

[Lance Roberts]

It's a bit of a hack job, but what you can do is take one of the female chainring bolts (nut, if you prefer) and cut that down to act as your spacer. Just remember to allow enough extra to fit inside the bolt hole on your crank.

Good idea, could just Dremel off the heads on the female nuts and screw them on to the bolt before put it through the spider. Will need some seriously long bolts then.

 

Only reason I don't like doing things like that is it will weaken the pressure points on each bolt. I'm pretty sure these things are made according to where the most pressure goes onto the mounting points and if you push it further away it might cause hassles, especially if the bolts will also have to be longer.

 

Just the way I see it, could be wrong.

[Captain Fastbastard Mayhem]

Just got some feedback from a supplier. Reckons on a 2x10 crank you should be ok without spacers because spider already more inboard than 3x10.

As I said, the chainline hasn't been an obvious issue for me on my 1x10 setup and I'm not increasing the angle between ring and cog given same width casettes.

Also haven't had chain line trouble on my 1x10 using slx 2x crank.

[richardkzn]

Hi, had the same problem with a 2 x XT crank, needed to install spacers between the spider and chain gear. Replaced the crank with a 2 x XTR and the distance between the spider and the BB is about 4mm less. Now I can use the chain gear without using spacers and the chain line is good.

[Captain Fastbastard Mayhem]

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.jpg

[NotSoBigBen]

Struggling to get my head around the problem of chain line ..... I mean normally the inner blade on a 2*1x is intended to be used on the 'upper' part of the cassette not so?

 

Hence if the single blade is mounted in that position one should not have a problem ... If there is a problem I would have rather imagined on the lower part of the cassette?

 

Of course if the blade is fitted on the outer part of the 2x crank I would imagine the opposite is true. On a 3x crank the middle should be ideal .... And is so as I have found anyway.

 

Of praat ek bollie?

[Captain Fastbastard Mayhem]

Struggling to get my head around the problem of chain line ..... I mean normally the inner blade on a 2*1x is intended to be used on the 'upper' part of the cassette not so?

 

Hence if the single blade is mounted in that position one should not have a problem ... If there is a problem I would have rather imagined on the lower part of the cassette?

 

Of course if the blade is fitted on the outer part of the 2x crank I would imagine the opposite is true. On a 3x crank the middle should be ideal .... And is so as I have found anyway.

 

Of praat ek bollie?

No, you don't praat bollie.

 

2x crank - big ring is generally outside, but going 1x you move it inside the crank arms to give you a better overall chainline (mirroring a more central position as if it were left on the outer edge, you'd have problems in 1st 2nd & 3rd from chain distortion)

 

I think it's due to what I explained above - the concavity of the new 11sp cassettes is pushing the granny (42t) closer to the spokes than a 10sp 11-42 would be. Hence more distortion on the chain. Even though the cassettes are the same width at the freehub, they're not the same width when you actually measure cog to cog. 

 

At least, that's my theory, given that I haven't actually physically measured it myself. Just thought about it and looked at the pictures. 

[richardkzn]

I think on a 2 x the biggest gear would be a 36t, on a 1 x a 42t or 40t this is the problem if I am not mistaken. The length of chain between the two sprockets (42t-front chain gear) is shorter so the angle is more.

[Captain Fastbastard Mayhem]

I think on a 2 x the biggest gear would be a 36t, on a 1 x a 42t or 40t this is the problem if I am not mistaken. The length of chain between the two sprockets (42t-front chain gear) is shorter so the angle is more.

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.