Chainline issue, hub or BB?

Hi,

I have been having some chainline noise issues with my Mash. I have replaced the rear cog, which sorted allot of noise out and have just replaced the chainring as the old one was worn. I have also put on a new chain.
However the drivetrain is still super noisy, and the chain it seems it not lining up in the centre as it hits the chainring, causing allot of chain vibration. The rear cog sounds fine.

Is this an issue of adjusting the chainline with a different size bottom bracket, or do I need to look at replacing the crankset as a whole? I do not have the correct tools at the minute for checking what size BB is currently on the bike. Is it also possible that the rear hub (Novatec) is not suited for a fixed gear application and sits to close to the centre of the dropouts?

Thanks

You don't have a ruler? To estimate offset from the centerline of the bike.

Can you take a picture, looking from the back of the bike towards the chainring?

How tight is your chain? There should be a little slack in it.

Sorry forgot to add the measurement, I got roughly 4mm off centre, which doesn't seems huge. The chain is also got a bit of slack in, all cleaned and well lubed. Ive attached a picture

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Are you saying the chain ring is approx 4mm off set from the sprocket? You can also estimate the distance of each from the centreline of the bike (i.e rear hub centre to sprocket centreline and seattube centre to chainring centre). Presumably these will differ by about 4mm and that is what you are finding. Once you have these centreline measurements you can use look at your options for achieving a better chainline.

If you try the picture again with the camera facing down a line parallel to the centreline of the bike it will be easier to see what is going on.

Hi Alex, thanks for your message, yes thats it, just measured again to double check and chainring centerline is 46mm and sprocket is 42. Taken another picture from the centre as much as possible, however from that it looks like the sprocket is further out than the chainring, which isnt what the measurements are saying so little confused. Let me know your thoughts, thanks

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I suspect that's because of perspective and/or distortion from the camera lens.
It doesn't matter too much though, the measurements you've taken are good enough.

You must either move the sprocket outwards or the chainring inwards by a few mm. For example, if the chainring is on the outside of the spider, you might get fairly close by moving it to the inside. Other solutions would be a shorter bb axle, different crankset, dished sprocket, spacers, &tc. https://www.lfgss.com/conversations/130300/newest/