Mountain Bike Drivetrain Upgrade Problem

[recoiljunky]

i just recently purchased a big-box Mongoose stat 29er for a beginner mountain bike and i had some parts laying around the garage from upgrading other bikes so i thought i'd put them to good use on this bike. from my giant escape i had a SRAM X4 front shifter off of a 3x8, and a shimano triggerfire 7speed shifter for the rear. now the rear derailleur is a shimano tourney tx, and the front derailleur is a no name brand. after installing all of the new components the front derailleur only will shift between first and third gear, even when going from one to two on the indicator. Also the rear derailleur now skips a gear at certain points on the freewheel. I have no idea what is going on now and figured this would be the right place to ask.

any help would be great thank

[droanx]

What shifter brand/model and rear derailleur brand/model on on the bike giving you problems?

[toot334455]

i just recently purchased a big-box Mongoose stat 29er for a beginner mountain bike and i had some parts laying around the garage from upgrading other bikes so i thought i'd put them to good use on this bike. from my giant escape i had a SRAM X4 front shifter off of a 3x8, and a shimano triggerfire 7speed shifter for the rear. now the rear derailleur is a shimano tourney tx, and the front derailleur is a no name brand. after installing all of the new components the front derailleur only will shift between first and third gear, even when going from one to two on the indicator. Also the rear derailleur now skips a gear at certain points on the freewheel. I have no idea what is going on now and figured this would be the right place to ask.

any help would be great thank

Im not sure what parts you put where: but its one of two problems
1.) different speed parts are not compatable with each other
2.) your parts are setup incorrectly.

My guess is there not compatable.
Different brands shift the rear derleiur different amounts between each shift,
and different speeds have different change widths and tooth widths.

heres a good place to start, print these off and follow them step by step:

Park Tool Co. » ParkTool Blog » Rear Derailler Adjustments (derailleur)

Park Tool Co. » ParkTool Blog » Front Derailleur Adjustments

Park Tool Co. » ParkTool Blog

if it doesnt work after this its a compatability issue

[recoiljunky]

I finally gave up and took it to the bike shop and they looked it over saying that all of the parts are compatible but they would have to look into why it is so far out of adjustment. Hopefully i will hear from them today or tomorrow about the problems with the bike