So a few months back I brought my custom single speed in to my LBS because of a popping noise coming from the bottom bracket area during the downstroke on the left side. When I picked it up they said the bb was a little loose so they tightened up and all is well. Well, I haven't really ridden the bike much since then and when i took it out this weekend on a real ride it started popping again after about 5 miles. It's the left side only and if i only pedal with my right foot, no popping. So it has something to do with the pedal force on that side. Any ideas what it could be? Bad bb? Problem with threading in the frame? Is it just loose again and I need to apply some thread lock or something?
My other issue I'm trying to figure out is some mad creaking from the handlebar area when mashing up a hill. Headset seams tight. What else should i look for?