raria

I have this cassette https://www.microshift.com/en/product/mtb-cs-h100-2/

on a 11 speed Shimano RS10 hub

with the 1.85mm spacer that came wit
the wheelset.

Everything shifts great but on the smallest cog when under load the chain falls of the $outside$ when on the largest chain ring! Edit, it stays on the Cog but the chain falls off the crankset!. It 1 x so no FD

GrainBrain

You need to adjust your rear derailleur's high limit screw.

Edit: Oh falls off the front. Well nevermind, I need to stop responding until Andrew "voice of reason" Stewart has!

Andrew R Stewart 

"Falls to the outside" in the rear or the front? This reference is usually for the front. Andy

raria

It stays on the rear Cog but falls off the chain rings on the outside Towards the pedals

Bill Kapaun

You need to adjust the FRONT DER.
That's obviously where the problem is!

Elvo

Chain might be too long, FD high limit screw might need adjustment, FD angle might need adjustment

raria

Also the chain doesnt fall off the front ring when i change gears.

It falls off only after I pedal underload.

zacster

I would try it without the 1.8 spacer or replace it with a smaller one so that the cassette moves in by that amount. Adjust your limit screws and cable accordingly. Apparently the smallest cog is so far out of alignment with your chainring that it just pulls off. 1.85 is the spec, but that is what would work with a double in front.

raria

The mlx 7000 RD is meant for 1 x

but

dsaul

More info is needed. If it is falling off the front, the cassette is not the problem. What crankset are you using?(so we can determine what the chainline is) If it is a 2x crankset with a single ring, what position is the ring? What chainring? (needs to be a narrow/wide ring designed for 1x)

Andrew R Stewart 

dsaul makes the same points that I was thinking of. Additionally this is why many 1x systems have a chain guide on the top of the ring. Sometimes the grass on that other side of the fence is just a different type and not greener. Andy

Bill Kapaun

Did you happen to swap the crank without changing the BB?

raria

I'm not sure the cassette has nothing to do with the problem. The bike ride fines when in everything *but* the smallest cog. It only slips of the crankset when: i) On the smallest cog and ii) Pedaling under load

The crankset is a 2 x here https://www.chainreactioncycles.com/.../rp-prod129442 Both rings are on the crankset and I'm talking only of when its on the largest chain ring.

According to this the chainline is 46.5mm https://shop.fullspeedahead.com/en/f...1ef946daba161/

I'm installing it on an RXC Pro Cyclocross bike

dsaul

That crankset has chainrings that were designed to be used with a front derailleur. The teeth are shaped to allow the chain to fall off for the purpose of smooth shifting and they are shorter than the teeth on a dedicated 1x chainring. It is not surprising that the chain does not stay on the chainring when you are at the extreme end of the cassette. The front derailleur not only shifts the chain between the chainrings, it also keeps it from falling off the chainring.

You need to use a narrow/wide chainring that was designed for 1x use or use a chain guide.

Andrew R Stewart 

Thanks for the better detail. Till now we thought that the bike had just one ring and no ft der. But now you're talking about a different bike? "I'm installing it on an RXC Pro Cyclocross bike" Or have you just installed it on this bike. This has been a fairly confusing thread to understand what's really happening to which sprocket on what bike Andy (who will now sit back and see what else comes up)

raria

Thanks for all your help. You are all great!

So its an unusual frameset (Cyclocross but with 130mm rear hub spacing)

I purchased a Cyclocross crankset to go with the bike and the fine print of the documentation says its designed for 135mm rear hub spacings and for 130mm hub spacing use a traditional road crank!

So is there anything I can do to fix this?

To make it every more crazy: the bike has a PF30 and the crankset is BB386 Evo.

So I have these spacers directly placed against the BB (as required by FSA).
And the crankset requires two additional smaller spacers and a wavy compression ring on the NDS!

Should I try removing the small spacers on the DS?

dsaul

The "culprit" is that you are using a double crankset without a derailleur. You can't just stick the chain on one of the chainrings and call it a 1x. You need to take off those chainrings and put on a chainring that was designed for 1x use.

raria

Unfortunately, it's not that simple. I tried putting on a FD and it didn't solve the problem and now the chain gets jammed between the outer of the chainring and the front derailleur when in the lowest gear under load.

I also notice that the chain runs quite noisy rough through the RD lower jockey particularly lower gears.

it's hard to believe but would 5 millimeters make such a big difference?

trailangel

Time for pictures

dsaul

The 5mm is actually only 2.5mm, because you are only concerned with the drive side of the hub. In any case, the narrower rear end would help the issue you are seeing. Your issue(aside from what I've already pointed out) seems to stem from the smallest cog being too far from the centerline of the bike and the 130mm rear wheel brings it 2.5mm closer to the centerline than it would be on a 135mm rear wheel.

I'm currently running a road double crankset with a 135mm rear wheel on my gravel bike with no issues and have mixed and matched various road and MTB components on several other gravel frames I've built. I know from experience that the chainline difference between road and MTB components should not cause the problems you are having.

We are going to need photos or you need to take the bike to a professional mechanic to sort out the problem.

raria

Here we go. Thanks in advance.

This is the spacers on the crankset. I need them all according to the installation instructions, but recall its for a 135mm hub size and my hub is 130mm






Here is the chain line with on the big ring and larger gear the RD is noisy here.



Here is the chain line on the big ring and a smaller gear. The RD is quiet but the chain falls on the outside of the cranks.


Here is the RD. The chain path is correct as far as I know (i.e. no simple errors like threading it over the tab)

trailangel

Can you post pics with Big/Big and Small/Small?
Big ring in front with big cog in rear, small ring in front with small cog in rear.

raria

Okay. Will do this when I get home. I'll also post a link to a video to show you what I mean by the RD running noisy.

raria

Video link of running Big back Big front and how noisy it is at https://www.dropbox.com/s/aek60vw83q...62229.mp4?dl=0 the grinding sound is from the RD the creaking sound is from the clamp for the stand I'm using.

Picture of big back and big front here



and small to small here

trailangel

What is that noise??
Is your chain bend?
new chain?
10 sp chain?