Mountain Biking - Tourney 21 spd upgrade - newbie help pls

I have a Saracen Traverse, bought recently second hand, like this
http://www.bikemagic.com/review/reviewproduct/mps/RPN/1381/v/1/sp/v/2
but the shifting is poor.

I have read that deore kit (or similar?) would be a good upgrade
Can I go up to an 8 cog set (9 is overkill for me i think) , or use a new rd (& fd?) with the existing cogs?
What is most important to upgrade - the rear cogs, front cogs & cranks or derailers?

Thanks in advance.

Jon

You will need to get a new cog-set (cassette or freewheel style). You will most likely need a new rear hub, because if they even make 7 speed cassette stuff is a mystery, and even if so, the freehub body will be too narrow to accept an 8 speed cassette. So, you need to tell us if you have a cassette freehub or a freewheel. To tell, look here.

www.sheldonbrown.com , clikck on the bicycle glossary and look up "cassettes"

Report back with your findings

To go 8 speed you would have to have shifters for one a rear derailleur a wheel that is 8 speed compatible a cassette and more than likely a chain. However 7 speed stuff is still made,like casettes der's freewheels, wheels and hubs. You can get STX RC pods in seven speed some shops still have 7 speed Grip Shift around. Some have Deore or XT thumbies lying around. Some even some Suntour stuff like me for example. For a wheel you could use a 8 speed hub and place a 4.5mm spacer behind the cassette and run 7 speed on it.
I could go on but that is enough.

When you say the shifting is poor, what do you mean? Is the actual shift mechanism not very smooth? Are the gears skipping? Does it not shift when you want it to?

Tourney may not be high end stuff, but you can make it shift reasonably well when it's properly adjusted. Deore will be smoother, but the costs of a complete upgrade is likely close to the cost of a new bike. Make sure the Tourney is properly adjusted and performing as well as it can before you replace it.

Guys, thanks for your help.

Trekkie820 - I will report back with whether it is a cassette freehub or a freewheel.

Hunter - I think there is much more to upgrade than I thought in going to 8speed, whell/hub, shifters (obvious when you think about it:-), fd so I will almost certainly stick with 7.

Stubacca - rd sometimes changes on its own, sometimes doesn't change when I ask. I think I have adjusted it OK but will revisit that. fd is a bit clunky but basically ok.

If readjusting does not improve things, then from reading the Shimano compatibility pdf's, I think I can just upgrade the rear mech to a Alivio or Deore, staying with the same chain/cogs/fd.

If I want to take it further I can up the chain to an IG31 or 51 and the crankset to a Alivio MC20 or Acera M340, still sticking with my rear 7 cogs and shifters. I'm not sure If this will be worthwhile for me.

If I have got this all wrong, I would appreciate you guys telling me.

Thanks again for your help.

Stubacca - rd sometimes changes on its own, sometimes doesn't change when I ask. I think I have adjusted it OK but will revisit that. fd is a bit clunky but basically ok.
Sounds like a derailleur adjustment problem to me. Could be a cable tension problem, could be a problem with the limit screws on the derailleur, could be the cable and housing itself being worn/damaged. Tourney really can shift fine when adjusted properly (which is the same for any system - XT will be hopeless if the settings aren't right!). I set a Tourney system up for a friend last year, and there was no problem with it.

Look at www.parktool.com in the repair section for great instructions on setting derailleur limits and cable tension.