Answered Chain coming off chainring

[pgrbff]

My son complains that the chain regularly comes off the chainring, it's an 11 speed allmtn Haibike, and this has happened from new.
Two questions combined. The first is "what does the arrowed item do and how is it adjusted?
The second is could the chain be coming off simply because of bad practise, cadence etc, or could there be another reason, ie item above not adjusted correctly? Or both?

 

[Jackware]

That's called the chainguide and it looks to be set correctly - ie at 38 for use with a 38 tooth chain wheel. Some bikes don't even use a chainguide so it's not always critical.

It maybe your son changing gear badly but it could be a part of the rear derailleur not set correctly. Some have a clutch mechanism to help keep the chain tensioned. If you can take a picture of the derailleur from the side we should be able to check that for you.

 

[pgrbff]

I thought it was the chain guide but didn't understand the relevance of the numbers. I never understood the need for a clutch on the derailleur until now either.
Side view of the derailleur.

 

[pgrbff]

Knowing nothing about modern bikes I thought the cassette was worn but I was told it looked OK on here. I didn't realise all of the radiused points were to help gear changes, I thought they were wear.
Despite all the scratches, the bike is only a few months old, just under 1000km, Tom is 12 and despite paying for it himself still not mature enough to have respect for money.
He's a bit gung-ho.

 

[Zimmerframe]

I thought it was the chain guide but didn't understand the relevance of the numbers. I never understood the need for a clutch on the derailleur until now either.
Side view of the derailleur.

View attachment 69245

View attachment 69246

Yup, your clutch is off, which makes it easier to change the chain and things. But should be on for riding to keep the chain tight - or it comes off the chainring ..

With it on, you should feel it's harder to move the cage forwards, with it off, it's quite easy.

 

[RustyMTB]

What Zim said. ^^^

The clutch is essentially a spring loaded device that keeps the jockey wheel cage tensioned rearwards & in turn, tensions the chain, so as to aid keeping it tight & on the chainring when riding. On for riding, off for maintenance, chain removal etc.

 

[Jackware]

Yup, your clutch is off, which makes it easier to change the chain and things. But should be on for riding to keep the chain tight - or it comes off the chainring ..

With it on, you should feel it's harder to move the cage forwards, with it off, it's quite easy.

So how does the OP move it to put it in the 'On' position?

 

[pgrbff]

So how does the OP move it to put it in the 'On' position?

Done it thanks.

 

[pgrbff]

Thank you all for your help. Hopefully no more questions for a while.

 

[andyb2]

it's worth noting that the position of the chain is important on a 'Narrow Wide' chainring. The outer chain plates should sit over the wide teeth on the chain ring. Looking at the photos, you seem to have that correct

 

[Zimmerframe]

So how does the OP move it to put it in the 'On' position?

For anyone else ... from the first picture, you just grab the "lever" and push it/lift it, backwards and it hinges just behind the "O" in off. It then rotates back and click into place. Turning it off, you just pull it forwards again.

 

[Jackware]

Thank you all for your help. Hopefully no more questions for a while.

No worries, keep asking and tell Tom to clean the grass out of jockey wheel

 

[RustyMTB]

Good groupset too, Deore. Can't go wrong with it.

 

[pgrbff]

This bike cost four times what I paid for my first car, back in 1979.

 

[aviserated]

The slightest bend of chain ring will cause chain to fall off. Check chain ring for bent wobble or loose chain ring nut.