Mountain Biking - Upgrading Shock..

Hi, I want to upgrade the shock on my Trek 6500ZX. I am not sure what year it is, but it is red with a white shock. I'll post a picture to show you. How do I know which shock will work? I am not sure if my shock is threaded or threadless, is there anyway to tell without disassembling it? I am new to mountain biking, so I would appreciate your help. Thanks!

From your photo, it's definitely threadless and looks like the popular 1 1/8" steer-tube diameter.

Since you have cantilever brakes instead of V-brakes, you also should make sure that your new fork has a brake-cable hanger like your present one, or else budget for a conversion to V-brakes. If your shifters are attached to your brake levers now, that would mean new shifters too.

As far as a fork, a single-crown 80mm-stroke fork with oil damping and fatter stanchions gets my vote. Marzocchi makes quite a range of worthwhile oil-damped forks, you might look for one of them. Like I mentioned, do make positively sure that you either get one with a cable hanger, or else budget for V-brakes (well, or discs...).

mechBgon covered it pretty well. You're good for any fork on the market seeing that it's threaded and is probably a 1 1/8" headtube. Cost will realy set your limits on what you can get. The more you spend the better it gets with forks, and brakes is a whole other issue that needs to be addressed. How much are you looking to spend?

Well.. I just want to get a decent shock off of ebay. I am getting $360 soon, but don't want to spend that much on just a shock. How much would it be to convert the whole thing to v-brakes not including new shifters? Thanks!

It doesn't look like the shifters are attached to the brake levers. Heres a pic:

In that case, you could move up to some V-brakes at the same time. When I worked in a bike shop last, there were some pretty nice brake/lever/cable kits coming from Tektro for really reasonable prices, so you might consider that option.

Well I already have to pay $50 to get new gears, so do you know approx. how much the whole kit will be? Can I buy it anywhere online? Thanks a lot

I see a kit that contains Alivio calipers and LX brake levers here (http://cambriabike.com/SALE/brakes/index.htm) for $29. They don't say if that includes the cables and housings or not. But once you add in the cables & housings and shipping, you might as well just buy a complete Tektro kit from the LBS. If you get it along with your gears, you may even get free installation, since I suspect they were planning on working on your brakes already.

if i were you i'd go ahead and get these:http://www.jensonusa.com/store/product.asp?number=05735 since they're cheaper, but from word of mouth these:http://www.jensonusa.com/store/product.asp?number=05068 are the best V's on the market

the arch rivals are cheap and can easily the Flak Jacket cables and you'd be good to go http://www.jensonusa.com/store/product.asp?number=06300

Look at the Avid SD 5 or 7 brakes, their very powerful and cheap.