Derailleur Problems: Help

Quoted post said:

Originally posted by Felipe512
Okay well I got a new MTB about 3 weeks ago, its a Fisher Tassajara, almost all deore components... here's my question: When shifting with the front derailleur I seem to loose my chain way to often. I mean it comes of like 1/2 the time im downshifting. I dont know if possibly im shifting wrong, or if the derailleur is messed up, but it just doesnt seem right. Can somebody help?

Make sure the derailer isn't bent and that the height, angle, and stops are properly adjusted.
Visit Sheldon Brown's site at URLs:
http://sheldonbrown.com/derailer-adjustment.html
http://sheldonbrown.com/cables.html
If after making sure the cable, housing, and derailer are all OK you still have a problem there is a device that will help if you are losing the chain while shifting down: Jump Stop by N-Gear. See URL:
http://www.gvtc.com/~ngear/

The derrailleur is almost certainly just out of alignment and adjustment. Try adjusting it following the instructions from the site listed above or if you bought the bike new from a shop take it to them. They should be responsible for tuning the bike they sold you.

ok well ill take it back to the shop where i bought it. Thanks for the advice.

Quoted post said:

Originally posted by Felipe512
ok well ill take it back to the shop where i bought it. Thanks for the advice.

...and keep taking it back to the shop that sold ut to you until you happy with the gear shifting!

It sounds like the set screws were not adjusted properly. Those are the phillips screws on top of the front derailluer. These screws limit the distance the derailleur moves. If you are losing the chain off of the granny gear, the low screw is out of whack. Throwing the chain off the big rings means the high screw is screwed. Also, it is very very important that the derailleur is parallel to the chainrings. This is adjusted by the clamp that holds the darn thing to the frame. Even a degree or 3 of misalignment will cause poor shifting. Also, very important that the derailleur is the correct height in relation to the chainrings. When bikes are assembled from the factory, they are typically not built well at all. When I worked at the shop, we took a brand new bike and readjusted the wheel bearings, headset, adjusted both deraillerus, trued the wheels, ect.. Amazing how all mass produced bikes are adjusted poorly. Good luck. Best thing is to read and learn how to adjust the componets yourself. In no time you will do better than the shop.