Originally Posted by Andrew R Stewart

Sorry to hear that you have more then one incompetent dealer in your area, maybe if we knew where you live one of us might have a recommendation for an experienced and motivated shop.

Crank arm tightening has quite a history here on this (and other) forum. Some searching in the archives should give you vastly more opinion. My opinion is to install the crank arms with correct torque and to revisit the tightness after an initial few rides. It is this second step that, IME, is not done and leads to the left arm (nearly always just the left) coming loose. Once the arm is ridden when loose the damage is usually done and the arm is likely to never stay tight even with periodic checking. I explain it as this. The arm is generally made of aluminum, which is softer then the steel BB axle. (And every Alivio crank set I have worked on/touched is aluminum, not steel). So when the arm is allowed to wiggle on the axle the axle acts as a auger and opens up the arm's hole (that the axle fits within). Once the hole is distorted the slightest amount the arm will most likely continue to wiggle on the axle. IIRC the torque level for the retaining bolts is between 30 and 36 ft lbs. Most consider this to be a pretty high amount of force when using a "L" hex wrench, especially if it's only 6" long.

One way to set a crank arm retaining bolt to the right range of tightness is to use a shop with a torque wrench for only checking/tightening your cranks. Many will do this for free (if you bought the crank from them) or very little cost. It's in the shop's best interest to be good to you, someone who in time might very well want a nicer bike. Andy