Chain rub

[Two-Wheels]

Sorry if in wrong forum. Wasn't sure if should post here or the general forum.

Basically I'm having a bit of chain rub & wondering how you sort it?
Only really noticed it after a bad gear change which was a little jammy/crunchy & since that it's only really noticeable in 2&7. Not sure what you guys call it but to me that's gear num 2 up front & 7 on the rear. Might happen in other gears but not noticeable like it is when set on 2&7.



See how that's fairly close.

Pedal on a bit and a gap opens up....



Which is in line with what can be heard - in that it's like a grasshopper sound every so often.


Now as I have a funny feeling any adjustment advice is going to include lingo that will have me posting back saying what's that, I come equipped with more photos ....







That's anything I can see in & about that area that may be linked to adjustment.


Just not sure how to alter it so that the chain rotates smooth/straight instead of going in & out as it must in order to be hitting off that (guard?).

 

[Oldhippy]

Loads of easy do videos on Internet and a good cycle repair book will explain how. However, if you go smallest chain ring to smallest cassette cog it will rub due to large off set and vice versa largest to largest.

 

[Cycleops]

Sounds like you're not too happy doing the adjustment. If you haven't got a bike stand you'll struggle anyway. Best to drop it in to your LBS , shouldn't charge you much to do it.

 

[Two-Wheels]

if you go smallest chain ring to smallest cassette cog it will rub due to large off set and vice versa largest to largest.

Yeah my point was this is fresh. It's never rubbed in this setting before.

Middle front cog, 2nd smallest at the rear.

Sounds like you're not too happy doing the adjustment.

It's not that I'm not happy, just that I don't know how.

I do have a stand. Got one to make cleaning the bike easier.

 

[Two-Wheels]

Ok YouTubing leads me to limit screws & barrel adjusters.

First video I watched said to get in at the limit screws.


View: https://www.youtube.com/watch?v=mj8HnAlPO1Y


That one says limit screws should be set & forget & I should be at the barrel adjuster.

Love it when you get conflicting info.

 

[Ian H]

If the chain moves in and out in one of the chainrings, then you've bent the ring. You might be able to straighten it sufficiently to make it work silently. Some ingenuity required if you don't want to or can't remove the rings.

 

[Two-Wheels]

If the chain moves in and out in one of the chainrings, then you've bent the ring. You might be able to straighten it sufficiently to make it work silently. Some ingenuity required if you don't want to or can't remove the rings.

That's what I was wondering.

With what they were talking about in the videos, I would imagine that there's a constant rub and no just at various points along the line.

Would a dodgy gear change bend the ring? To be honest I'm not 100% on what lead up to it. At the point I started noticing rubbing I tried thinking if anything wrong had happened recent. I think I was in too high a gear for what I was doing & started changing down but it wasn't smooth.


And while I'm at it - I may as well ask worst case scneario of just continuing as it is and how likely this worst case will be?

I appreciate any answer to that isn't 100% nailed on & it's just speculation based on something some random guy on the internet said.

Still thought i'd ask all the same.

 

[Ian H]

It can only be slightly out of true. An alternative explanation is that it was always out of true and that you have slightly bent the cage of the front mech. Check whether the outer plate is parallel with the big chain. If it's not, it's usually possible to bend them back by hand.

 

[Two-Wheels]

Well I went out & had a look.

Everything looks straight to me. Though to be fair, with as much as it's coming in & then going back out, it's only a little bit, so anything that isn't right is only going to be a little bit not right & therefore to the know-nothing - difficult to spot.

As I don't have a clue what I'm looking at I'm just going to see the local bike shop tomorrow. Will probably be a 2 week wait at best as they're always busy but I'll see what's said. Better leaving it with someone who has half a clue at least.

 

[Ajax Bay]

1) This is front derailleur stuff (don't worry about rear/sprockets).
2) If your chain is oscillating laterally as the cranks are turned then either you have a bent chain ring as @Ian H has said, or one or more chain ring bolts (of five or four) are loose, or (v unlikely) spindle is off. Needs sorting.
3) This is occurring middle ring of triple. Not a 'limit screw issue'. Need to get the cable tension right (see videos above) In the inner ring and largest sprocket max 1mm gap to inner cage plate and zero cable slack (even v slight tension) (with shifter in '1').
It's a brave person who says they've mastered FD adjustment and with no screw adjustment (unless installed as an 'extra') tweaking is not as 'easy' as RD fettling.

 

[roubaixtuesday]

2) If your chain is oscillating laterally as the cranks are turned then either you have a bent chain ring as @Ian H has said, or one or more chain ring bolts (of five or four) are loose, or (v unlikely) spindle is off.

Would failing BB bearings with play in them also have this effect?

 

[Ian H]

Would failing BB bearings with play in them also have this effect?

The OP says it happened suddenly after a bad gear-change.

 

[Two-Wheels]

Plus if BB stands for bottom bracket then I had that changed out at the back end of last year.

Nothing premium. Some square thing from memory.

Anyway, I'm to take it in tomorrow which was better than I thought. They mentioned something to do with noise & these square bottom brackets. I know I'm not helping you guys out any being so vague, apologies. My memory is awful & it was only yesterday morning.

I said that it had been fine & just started to make the noise, plus it was visibly coming in & going out. Not majorly so, but you could still see it.

Anyway, chap said bring it down Wednesday so hopefully it's sorted by this time tomorrow & doesn't cost too much.

 

[Ajax Bay]

Decent cartridge square taper bottom brackets typically have considerable longevity (15,000km+). But if there's lateral movement the one the O/P had installed seems defective.