Need some help with a drivetrain issue

on my mountain bike, when I am on the small chain ring up front, occasionally it will lock up the chain, I have to pedal backwards then forwards again to straighten it out. it will get more frequent the longer I ride in the woods, presumably from any diDr buildup. if I run the 2nd ring I won’t get any issues. what could be some possible causes?

how clean is your chain? and lubed.

chain is good and freshly lubed

sounds like a classic case of chain suck, it can be a real pain to correct. Mostly it tends to happen when things get real muddy but if that is not the case I’d probably start by checking the teeth on your chainring to see if any are damaged, bent or worn. It may be time to replace the ring.

I took a look, they don’t look too bad, but I’m going to get a crank puller so I can take them off to take a better look, and clean them up

You might want to read up on chain suck here http://fagan.co.za/Bikes/Csuck/ and see if anything applies to your situation.

If any doubt at all, and the chain is known to be good/measures good, than just replace the granny ring. Steel is better, as well, specially stainless. It wears better to start with, and doesn’t seem to hold the chain as bad either. If you are going to be pulling the crank, I’d spend the extra 25 bucks and get a ring. Be warned, though. If the chain is not great after all, you may need to replace that as well. And at that point, it would be a safe bet to say the cassette should be done as well.

I had this issue with the Concorde racing at Gore in the Provincials last year. No use of granny ring when it got mucky, so I was stuck with a 36 tooth middle ring and a 12-28 cassette. Makes you climb faster, but burns more matches when the clock is ticking!