Chain off mid trail.

Hi there.
My chain keeps coming off the chainring mid trail. I keep it in the middle ring and it seems to always happen just as I’m trying to peddle hard to a feature. It’ll slip off them come back again.
Any advice? Had a little look online and in some books but can’t seem to find a cure.

Worn chainring? Knackered chain?

Chain too long?

Loose mech bolt?

Chain might be too long. What gear are you in at the back? Are you cranking fast downhill when this happens? For the top (faster) half of the cassette when going downhill, use the big ring to get less chain slack n slap. Just remember to get back to middle ring when you need easier gears.

It happens when I’m really cranking it up hill. The Bike is only 6 months old. Guess I’ll try an ultra clean and then check everything is tight. And if it still happens shorten the chain a bit.
Thanks for all your input.

Uphill. Hmm. Any damaged teeth on the middle ring?

Hang on – it comes off and then back on again? Doesn’t sound like it is slipping off the chainring. More like gears skipping at the back. Readjust. Or might be new chain and cassette time?

Loose chain ring bolt?

Front derailliuer not quite spot on?
When you say its skipping off then coming back on, is it going up or down?
You might be able to loosen or slacken the cable barrel adjuster accordingly.

It’s slipping down. The front derailliuer seems to be set ok when I’m in the middle ring. It always seems to happen just as I’m trying to really pust on a bit of up hill on a rooty bit of single track. Very enoying.