Chain keeps coming off

[BrumJim]

Just looking for a few thoughts.

My son's chain keeps coming off his chainring. Did it 4 times yesterday during cyclo-cross lesson. He keeps asking for a chain catcher.

Bike is running 11 speed Shimano 105 with double chainring.

A few ideas. Please feel free to add.

1. Get a chain catcher.
2. Convert to 1x for cross season, and run a chain guide and high/low chainring.
3. Adjust the front derailleur so that it only just moves the chain onto the small front chainring. That should help.
4. Clutched rear derailleur. Whatever that it.
5. New rear derailleur. Spring has lost its strength, and allowing too much chain slap, increasing the risk of dropping the chain.
6. I've just fitted a new chain. Old one was a bit worn, and although the gears don't jump, he needs a new chainring and/or rear cassette as they aren't snug enough.

 

[T4tomo]

if its coming off the inside of the small ring when he's changing down then

3. Adjust the front derailleur so that it only just moves the chain onto the small front chainring.

should be first port of call, you be able to see how the cage sits relative to the chain quite easily and tiddle the limit screw to adjust

if its just falling off as he's ring along then maybe

4. Clutched rear derailleur.

although that could still be above if FD is properly badly adjusted on limit screws -

 

[Paulus]

I'd go with adjusting the limit screws first of all. Give the FD a good clean before adjusting the screws.

 

[alicat]

7. Get him hooked on gaming instead - it will save you heaps of bike fettling.

You're welcome. I'll get me coat.

 

[Sharky]

Chain too long?

Is the freehub running smoothly? If this is sticking, every time you freewheel, the chain will keep moving and then come off the chain ring.

 

[figbat]

5. New rear derailleur. Spring has lost its strength, and allowing too much chain slap, increasing the risk of dropping the chain.

Is this what you've done or a suggested failure mechanism? If the RD is not tensioning the chain well then this could easily cause the chain drops.

Under what circumstances is the chain dropping? Riding over rough ground? Changing gear? Back-pedalling?

 

[si_c]

7. Get him hooked on gaming instead - it will save you heaps of bike fettling.

You're welcome. I'll get me coat.

Have you seen how much PC gaming hardware is these days?

 

[wiggydiggy]

1. Get a chain catcher.
2. Convert to 1x for cross season, and run a chain guide and high/low chainring.

I didn't think a chain catcher/guide was compatable with a double? I though they were for single chainrings?

I've just had the same issue on my (none Cyclocross) 1x8. Turned out the original chainring fitted was not a high/low (my LBS called them thick/thin so I'm assuming same thing), and though I tried a chain guide it didn't work, and luckily a high/low (or thick/thin) chainring has solved it.

 

[Sharky]

I didn't think a chain catcher/guide was compatable with a double? I though they were for single chainrings?

I've just had the same issue on my (none Cyclocross) 1x8. Turned out the original chainring fitted was not a high/low (my LBS called them thick/thin so I'm assuming same thing), and though I tried a chain guide it didn't work, and luckily a high/low (or thick/thin) chainring has solved it.

I think the terminology is a "narrow/wide" chainring.

 

[Dogtrousers]

I didn't think a chain catcher/guide was compatable with a double? I though they were for single chainngs?

I've never owned or used a chain catcher so I'm not expert but I am a great browser of bike bits online shops and I've definitely seen them advertised as being for a double. Eg this was the first that came up when I did a search.
https://www.i-ride.co.uk/products/c...ar-spares/chain-drop-catcher-for-road-double/

 

[presta]

I didn't think a chain catcher/guide was compatable with a double? I though they were for single chainrings?

I'm using one with a triple.

 

[geocycle]

Dog fang chain catcher has worked well for me. Despite my best efforts at setting limits I managed to throw the chain off about once a ride when changing down. Some of this I’m sure is technique and it usually occurred when changing quickly. Since I fitted it the problem has gone. This was with a Spa subcompact double and 11 speed 105.

The grx kit on another bike comes with a clutch and I’ve never had a problem with the chain coming off without a catcher whether I’m riding with clutch on or off. I think this might simply be better kit that has been well set up.

 

[wiggydiggy]

I've never owned or used a chain catcher so I'm not expert but I am a great browser of bike bits online shops and I've definitely seen them advertised as being for a double. Eg this was the first that came up when I did a search.
https://www.i-ride.co.uk/products/c...ar-spares/chain-drop-catcher-for-road-double/

I'm using one with a triple.

I think I've confused a chain guide with a chain catcher. I'm talking about something like this which sits above your chainring in lieu of a front derailler and is supposed to keep the chain on.

 

[sevenfourate]

Firstly - good luck to the OP and Son with the issue. That must be bloody annoying to say the least….

On a side note (It is mentioned here though) I’ve just bought a Trek Hybrid (Will only ever be used on dry tarmac) - and a Trek MTB….to be used off-road in Winter. Both have identical Deore clutched rear derailleur(s).

How should I be setting / using these for each use ?

 

[BrumJim]

Is this what you've done or a suggested failure mechanism? If the RD is not tensioning the chain well then this could easily cause the chain drops.

Under what circumstances is the chain dropping? Riding over rough ground? Changing gear? Back-pedalling?

Riding over rough ground.

Tried adjusting the FD, but it seemed to be spot on already.

Rear derailleur appears to be loose, though, with a fair bit of lateral play.