Chain ring weirdness

[griffter]

Hi All, looking for a pointer as to what’s going wrong please. I’m 99% roadie but have a 1x10 mountain bike for when the tarmac isn’t calling.

It’s a Marin Hawk Hill, it’s 3.5 years old and it’s probably done about 150 miles. Hence I am reluctant to believe the chain or chain ring has worn out but here goes:

Today when riding I heard a clicking sound like the mech wasn’t properly aligned. I checked and double checked and all the gears selected positively and correctly. I kept riding and the problem persisted. The lower length of the chain was flapping up and down like a guitar string. Riding looking down at the chain ring (as opposed to where i was going) I noticed that the chain ring was “hanging on to” the chain causing the noise and causing the chain to vibrate. The problem got worse and the chain started to hook up on the rear stay. The following photos show what happened (recreated in my garage hence no mud):



Here’s a close up of the chain ring:



The bike was unridable in anything but first gear as the angle of the chain meant it kept hooking up.

Rinsing home on the road, building up a bit of speed and going up the gears, it got better but still very sticky.

I keep the bike clean and lubricated. It is just that it got caked in mud and water (I was riding down some streams) and the chain/chain ring got “sticky” or is it something to do with the profile of the chain ring? Worn chain? Or known to be problematic? Is Deore.

I did get a stick stuck in the spokes last week and broke a spoke which could have stretched the derailleur spring, although there seems to be plenty of tension, but could that be it?

Any pointers gratefully received - and happy new year!

[gl20]

Not sure if this helps but I had a problem on my road bike Of the chain going slack that I traced to the sprin FB mechanism for the cage (to make it doing rearwards and take up any chain slack) had gotten sticky / bunged up. Stripping and cleaning it sorted it. No replacement parts neeeded. I know you said you keep the overall mechs clean but wondered if you’d missed that? If you take the tension off the cage and pull it forward, does it spring back cleanly?

[ian in lancs]

From your description I’d be looking at the rear derailleur spring too.

[irc]

Believe this is known as "chain suck" so googling that and Shimano 1*10 may get some ideas.

I've had it on a triple tourer. Caused by worn chainring. But that was after thousands of miles not 150.

Possibly a damaged derailleur spring could cause it as well.

[Skyrocket21]

Have you removed the rear wheel? Check it's seated correctly. Check the rear mech hanger to see if it's straight, check they haven't come loose. Check your chainring bolts too and for any movement in the bottom bracket. Buy a chain wear measuring tool. For 150 miles that looks like quite some wear on the teeth, buy some decent lube! Just could need setting up, maybe the chain is too long etc.

[snotrag]

Chain suck.

Is your clutch switch still turned on?

[WestyCarl]

Looking at the teeth on that chain ring I believe it's done more than 150 miles. I'd replace it and also check the chain wear.

[Spitwad]

snotrag said:

Chain suck.

Is your clutch switch still turned on?

My first thought too. If the lower chain is flapping about, I'd be checking the clutch is operating normally/not accidentally locked out. And the chain ring looks ok to me. It's narrow wide so the teeth should be alternately uneven.

[griffter]

gl20 said:

Not sure if this helps but I had a problem on my road bike Of the chain going slack that I traced to the sprin FB mechanism for the cage (to make it doing rearwards and take up any chain slack) had gotten sticky / bunged up. Stripping and cleaning it sorted it. No replacement parts neeeded. I know you said you keep the overall mechs clean but wondered if you’d missed that? If you take the tension off the cage and pull it forward, does it spring back cleanly?

Thanks. I squirt, scrub it and spray it but I haven’t stripped it so I’ll check that. The mech does tension the chain ok but the spring looked a little slack to me (although seemed to work).

[griffter]

Skyrocket21 said:

Have you removed the rear wheel? Check it's seated correctly. Check the rear mech hanger to see if it's straight, check they haven't come loose. Check your chainring bolts too and for any movement in the bottom bracket. Buy a chain wear measuring tool. For 150 miles that looks like quite some wear on the teeth, buy some decent lube! Just could need setting up, maybe the chain is too long etc.

Thanks. Yes, yes and yes! Noted on the chain wear indicator though, thanks. I tend to replace them periodically on the road bikes but have never been very scientific about it!

[griffter]

snotrag said:

Chain suck.

Is your clutch switch still turned on?

I’ve never known what this does! When should I use it? I did check it was “off” and allowing the mech to move freely, but as I say I have no idea when it should be “on”.

[griffter]

Thanks all for replies. All sincerely appreciated. Looks like checking the derailleur spring is prime candidate, and checking the chain. I think the chain ring has always looked like that. Reminds me of gappy teeth .

I’ll Google chain suck later. Again much appreciated thanks

[Spitwad]

griffter said:

I’ve never known what this does! When should I use it? I did check it was “off” and allowing the mech to move freely, but as I say I have no idea when it should be “on”.

The clutch is essentially a tensioning device designed to keep the chain...er, under tension. Shimano drive trains have a plastic bar that pushes backwards & forwards to actuate & Sram use a button. Either is easy to check - just push the mech cage from behind & if the clutch is on, it should spring back to tension the chain.

Sounds windy in the explanation but will be obvious when you check it. Good luck with it.

[jimmy156]

griffter said:

snotrag said:

Chain suck.

Is your clutch switch still turned on?

I’ve never known what this does! When should I use it? I did check it was “off” and allowing the mech to move freely, but as I say I have no idea when it should be “on”.

Surely the clutch should always be on, otherwise why have it! (The clutch helps keep tension in the chain over bumpy ground)

I think only turn it off to remove wheel / service the gears etc

[Spitwad]

jimmy156 said:

Surely the clutch should always be on, otherwise why have it! (The clutch helps keep tension in the chain over bumpy ground)

I think only turn it off to remove wheel / service the gears etc

Spot on Jimny, yet I've had chains go only to find the clutch is off & wondered how that happened. I guess people who've blown mech hangers on tree stumps & ended up doing the walk of shame will say I'm lucky

[CoolHands]

That chain ring looks like it is made out of melted plastic

[gazza285]

CoolHands said:

That chain ring looks like it is made out of melted plastic

Doesn't look very clean either.

[gashart]

Absolutely totally chain suck, need to spend some £££

[griffter]

Re the clutch switch with it on the mech is locked in place. I assumed you might use it for some crazy downhill exploits to stop the mech moving and the chain coming off? With it off the mech tensions the chain under spring tension as with all my other mechs. Maybe I need to understand this more. Is it literally on/off or (like a gearbox clutch) is a range of slip possible?

Re chain suck, this is sounding very likely. Thanks again for the pointer. As I said, yesterday I was riding down paths running with water. The ground was basically sand in places. The following article highlights grit and dirt as a prime cause. Given it started straight after I’d finished the descent, this seems to be more than a coincidence:



I’ll check all the suggestions above (and properly clean the chain, ring and mech) and after painting the rear stay install something like the following:

[gazza285]

The clutch is one way, the spring tensions the chain as normal, and the clutch resists the movement in the opposite direction, preventing unwanted chain bounce.