Derailleur Question
 

I have a low end Claris front Derailleur that goes out of adj. about every six month The LBS says it's because the Chain Rings aren't angled at the top and that's why the shifting is off. (And not the derailleur cable.) BTW, they are trying to sell me "better" chain rings that are super $$$. Are they pulling my leg? Is there a good way correct this without costing a arm and a leg?

Just consider that mechanical things need occasional maintenance. Adjusting a derailleur every six months is a minor sort of maintenance. The best way to "correct this" is to learn how to adjust that front derailleur. Then, you're not depending on what someone else thinks, or worrying about their motives.

find a different lbs. doesnt add up.

How much out of adjustment? A quarter turn of the barrel?

As an ex bike store owner I can say that unfortunately that there are bike stores that have employees who act like vultures, preying on the people who enter their store. When you say out of adjustment, their are three four facets to derailleur adjustment. There is correct height, Angle, Cable tension and then there are the limit screws, I do not know which facet yours has issues, I do not see new chainrings as a F.D. ? necessary solution. If somehow the chainrings do not have low spots at the top and bottom, you can easily file them 1/16 th of an inch Even if the large chainring does not have shift ramps, it will shift fine. I have read on this forums before about cyclists that their chainrings are warn out I'll sell you new ones. Because on a 50 tooth chainring the chain is always riding on 25 teeth, it would take some awfully high mileage years to wear one out. I have had some 10,000 mile plus years, and my chainrings don't show any appreciable wear.

Poor chain rings could be the cause of shifting that is NEVER right, but if you can get the derailer adjusted correctly, and it shifts well for a while, but eventually falls out of adjustment, that shouldn't be caused my the chain rings (as good or as bad as they may be). I think you have something else going on with your setup...are they replacing cable housings and ferrules every time they fix the adjustment, or are they just using a barrel adjuster to adjust the derailer?

i'd have the cable & housing replaced by a different shop.

When my FD acts up, it's always the spring. It gets balky. I need to use WD40 and work it back forth until it comes back to life. Is this what your FD does?

Does not seem like excessive adjustment frequency to me; I would only be concerned if the derailleur suddenly needs more frequent adjustment, due to possible cable fraying.

Only time I've replaced a front c.ring is to appease aesthetics for my own personal sake. Was also cheaper to replace it then to address the original one to make it mediocre at best.