Chainline on 1 x system.

[Eugene]

I am busy building up a bike. I used an Alivio 3 x Crankset and converted it to 1x. 

The problem is that the chainline is completely out. In a straight line, it sits somewhere on the 9th gear of a 10 speed cassette. The result is that the chain simply derails off the front chain ring as it moves up the cassette. 

I cannot think of anyway to fix it, other than replacing the crank. 

Before spending the money, are there any ideas to fix this? 

[NC_lurker]

Which chainring are you using, outer or middle? With a 3x you should have some options.

[ChrisF]

Also check your crank installation.  On the Mongoose it had shims that we could move to adjust the chain line

[Sid the Sloth]

Are you using a narrow-wide chainring? It helps with chain retention, other than that chain length and derailleur spring tension are pretty important - I am running 1x on my road and gravel and have noticed it’s exceptionally responsive to these things. Hope you come right. 

[RobertWhitehead]

Please ignore stupid or obvious comments and use the better ones 

1) Are you using a NW ring? This may explain why it drops (can be a stupid comment) 

2) Is the chain the correct length (again, this can be idiotic) 

3) As per NC you can use the middle or outer ring position but if the chain drops then moving the ring won't help much, you'll still get some grinding closer to the top. 

4) Are the crank arms straight or do they have a natural bend in the arms around the middle. If straight you won't have much to play with in point 5

5) What's the width of the BB you have installed? You will notice that the BB is most likely a 118 or longer to accommodate the 3x. It is possible for you to get a shorter BB which will eliminate the issue. But, you may need to play with some options or post some kiekies and I can assist. 

If all else fails it is time to get a new bike 

 

Edited October 28, 2023 by RobertWhitehead
Skarramoesh

[Eugene]

It's the outer. The single ring cannot be mounted anywhere else on the crank (104 BCD) 

[Eugene]

44 minutes ago, NC_lurker said:

Which chainring are you using, outer or middle? With a 3x you should have some options.

It's a NW 1x chain ring and therefore it can only be mounted on the outside (I put it on the inner part of the plate) 

[NC_lurker]

(Going for most unhelpful suggestion podium)

Mmm, ok then perhaps your easiest option is just converting to single speed...

Sorry, your issue is beyond my pay grade. 😆

[Eugene]

13 minutes ago, RobertWhitehead said:

Please ignore stupid or obvious comments and use the better ones 

1) Are you using a NW ring? This may explain why it drops (can be a stupid comment) 

2) Is the chain the correct length (again, this can be idiotic) 

3) As per NC you can use the middle or outer ring position but if the chain drops then moving the ring won't help much, you'll still get some grinding closer to the top. 

4) Are the crank arms straight or do they have a natural bend in the arms around the middle. If straight you won't have much to play with in point 5

5) What's the width of the BB you have installed? You will notice that the BB is most likely a 118 or longer to accommodate the 3x. It is possible for you to get a shorter BB which will eliminate the issue. But, you may need to check play with some options or post some kiekies 

 

1. Yes, narrow wide

2. The chain is on the smaller side. I should probably get a longer one as it is on the cusp of being too small

3. It can only be mounted on the outer plate. 

4. There is a slight bend. 

5. Not sure of the bb width. It is a square taper. 

I think I should just swallow my pride, accept defeat and take it to a bike shop. 

[Koos Likkewaan 2]

15 minutes ago, Eugene said:

It's a NW 1x chain ring and therefore it can only be mounted on the outside (I put it on the inner part of the plate) 

I guess this is what you mean already, but it should go where your middle ring used to be.

If it is only in line whe  in 9th gear, even more important that this is the case.

Secondly, as mentioned already, spacers on drive side of the BB can be moved to non drive side, effectively moving the chainring closer to the frame, ensuring better allignment.

Lastly, look at the offset of NW chainring. 6mm offset should also help here.

[RobertWhitehead]

If you're in Gauteng I will be able to help in getting it sorted. My guess is that the BB is too long and will be quite simple to swop and bring into alignment. Those square tapered BBs are very cheap. 

[Barry]

You could also look at an XT  derailleur that has a clutch. Alivio 1x10 will still jump off when going gets tough even with a NW chainring.

[Eugene]

10 hours ago, RobertWhitehead said:

If you're in Gauteng I will be able to help in getting it sorted. My guess is that the BB is too long and will be quite simple to swop and bring into alignment. Those square tapered BBs are very cheap. 

Thanks for the offer, but I am in PE

[Eugene]

8 hours ago, Barry said:

You could also look at an XT  derailleur that has a clutch. Alivio 1x10 will still jump off when going gets tough even with a NW chainring.

It's the crank that is Alivio not the derailleur. 

[Barry]

7 hours ago, Eugene said:

It's the crank that is Alivio not the derailleur. 

Ok so NW chainring on the outside and maybe a few mm shorter BB axle. If the rear derailleur is a non clutch on a 1x10 then you will get chan whip and the chain jumping off infront. 

[dasilvarsa]

Post some pictures