Bike problem?

My bike makes a clicking sound and it feels like it's grinding or changing gears every 4 pedal revolutions. If I pedal 3.5 revolutions and just coast, when the fourth revolution is finished it makes a much smaller clicking noise and the grinding isn't so bad. What causes this and how can I fix it?

It sounds like a bad spot in the chain to me. Look for a kink or sticking links in your chain. This would be most noticeable after the chain passes through the sharp bend of the derailleur pulley.

have you tried tightening your crank?
mine did that and when i tightened it, the sound was gone

As another respondent pointed out, it sounds like a stiff or perhaps a bad link in your chain. Best to have someone hold your rear wheel up. Then pedal very slowly while carefully watching the chain as it passes through your rear derailleur. More than likely you will see it hop as it goes through the derailleur and around the gear cog on the cassette.

If the link is coming apart, the chain will need to be "cut" and the bad link removed. This will require a chain tool to accomplish.

If the link is merely stiff, you need to get it loosened up. To tell if it is stiff, try moving the link up and down. If it does not move freely like the others, then you have a "stiff" link. You can try gently flexing the link sideways a few times to see if it will loosen. If this doesn't help, try very slightly pressing the pin back and forth using a chain tool to get it loosened.

If you are uncomfortable with this or unable to find the cause of the problem, take it to a bike shop. This should be pretty cheap and easy to take care of.

Hope this helps.