Dropping Chain on single chain ring

[celeste boy]

Hoping someone can be of help here.
I have a 40 tooth single chainring on the front and a 10 speed Shimano cassette on a 29erMTB. The bike is a year old and I dropped the chain 3 times this afternoon- coming off the front chainring and going 'out'.
It happened under identical circumstances, going downhill fast in a fast gear and hitting road bumps.
Too many teeth in the chain or chain stretched? or do I need a plastic type cover that fits outside the chainring to hold the chain there? You see, with no front derailleur, there are no limiting screws.
Thanks in advance,

CB

[softy]

Stuff happens,
My chain drops once a weak, it is a certain combo of gears and the chain gets a whip, off it comes. No biggy.
Sounds like you have had a pretty good run. Just get a small stick off the side of the road, hook the chain and guide it back on the ring. A minutes work and done.

[Nobody]

...or do I need a plastic type cover that fits outside the chainring to hold the chain there?

I have one of these on my road bike. Good insurance IMO.

[KGB]

1. Make sure you are running the shortest possible chain length.
2. Get a narrow-wide chainring.
3. Get a clutched rear derailleur.
4. Do none of the above and fit a chain guide that goes over the inside and outside of the ring.

A "fast" gear means you're down in the small cogs on the cassette so the chain tension is at its lowest and the chain is bouncing around everywhere. The chain line this gear creates will mean it almost always drops off the outside of the chainring.
Chain guides are good but can get clogged up in nasty conditions - this may or may not be a problem for the riding you do.
Riding style (selecting lines, when and when not to pedal) may play a part as well.

As to why its happening now and not before. ..? No idea.

[celeste boy]

Thank you for the quick replies. I did a search and maybe a 'bashguard' is the answer?

When 'softy' says this happens each week and it is no biggie - well I just don't think that is the right thing to be happening. Surely these modern drives can handle the bumps? And I am sure the racers would be really p'd off if it happened in a comp event.
BTW rear derailleur has a clutch.

CB

[elfoam]

Thank you for the quick replies. I did a search and maybe a 'bashguard' is the answer?

When 'softy' says this happens each week and it is no biggie - well I just don't think that is the right thing to be happening. Surely these modern drives can handle the bumps? And I am sure the racers would be really p'd off if it happened in a comp event.
BTW rear derailleur has a clutch.

CB

It happens even on the the smooth roads of the Tour on the best road bikes the world has to offer. Dont feel too bad.

[eeksll]

when i had a single chainring setup, mine dropped multiple times a commute. Sometimes due to bumps, other times for no reason that i could see. It did have a long cage RD on it (it didn't need a long cage RD but thats what I had).

Ended up putting the FD back on and used the limit screws to place it where it needed to go.

[Nobody]

Ended up putting the FD back on and used the limit screws to place it where it needed to go.

Did that on my other road going bike.

[RyanA]

Just to add my experiences to the mix:
On my commuter I was running a deore 9 spd with a single ring up front (not a narrow wide ring) I never dropped a chain. Then I switched to an 11spd 105 setup, retaining the same front ring. I would drop a chain every 50 or so km's, in varying circumstances (sometimes shifting, sometimes pedaling through rougher stuff). I have now put on a narrow wide ring (around 120km's ago) and so far haven't had any drops (and I have been trying to drop it, just to test it).

[Nate]

I run a single speed with 1/8th on a very hard commute & never had a drop.
I'd look at chain tension, also cog alignment - maybe they're ever so slightly mis-aligned.

what about the pitch of the cogs? are they all the same? chain the same?

[Mugglechops]

You need a narrow wide chainring. Been running one for 5400kms on my hardtail and never dropped a chain.

Last 2000kms have been fully rigid on some pretty rough tracks at times.

[celeste boy]

You need a narrow wide chainring. Been running one for 5400kms on my hardtail and never dropped a chain.

Last 2000kms have been fully rigid on some pretty rough tracks at times.

Now that the experts are on the case, I have just realised I have a narrow wide chainring on the ss and do not have the problem of losing chains.
Should I still go for the bashguard?

CB

[Mugglechops]

It shouldn't matter on your singlespeed if everything is tensioned properly.

Never lost a chain on my singlespeeds before and that was from years before N/W chainrings came out.

[find_bruce]

Now that the experts are on the case, I have just realised I have a narrow wide chainring on the ss and do not have the problem of losing chains.

It shouldn't matter on your singlespeed if everything is tensioned properly.

Never lost a chain on my singlespeeds before and that was from years before N/W chainrings came out.

So if your singlespeed has a 40 tooth chainring - swap it to the MTB & problem solved Sod's law suggests however that your ss doesn't have 40 teeth

[celeste boy]

Thank you for all the replies and advice.
I am now in a position to tell you the 'answer' to my chain dropping.
I tried using a bashguard but the chain continued to jump and got caught between the chainring and the bashguard.
When the narrow/ wide chainring arrived, I put that on and have had no problems since despite a long, bumpy, gravelly ride.
Narrow/ wide seem to be the way to go. (But they only go up to 38t!)

CB

[Duck!]

N/W ring on a single-speed is pretty pointless, 'cos if the chain is tensioned properly it should be impossible to drop. So take the N/W off the SS & chuck it on the single-ring multi-gear where it will actually work, and throw the normal ring on the SS.