can't get chain to low gear

[NRSracer]

I have a 21 speed bike, and i can get the chain to get in high and middle gears in the front, but i can't get it to go into low gear.

[spag52]

nm

[muddywolf]

please bear with me as I have been nursing the fat tires this evening...

it could be your low gear stop screw in to far, shift into low on the back and front, put the chain on your small gear in front since its not dropping. I usually start by setting the inside cage plate about 1/8 inch from the chain and adjust in or out from there depending on how the chain falls
also check the allignment of the deraileur, the cage plates should be parallel with the chain rings, and about 1/8inch above.
and cable tension, with the chain on the low gear in the back and middle on the front, the inside cage plate should be allmost rubbing the chain.
hope this makes sense and helps, if not I can get more detailed