I just upgraded my 1998 Cannondale hardtail with a 2006 Kona Kikapu Deluxe. Talk about a world of difference. But, I have some very basic questions regarding the suspension:

1) Why is it called a 4-inch travel bike? Looking at my rear shock (Fox Float) and at rear shocks online, the dimensions are (example) 7.875" x 2". Wouldn't this mean the rear shock only travels 2"? I initially thought that it might be 4" total travel (front and rear), but I get about 3" out of the front fork (Marzocchi MZ3).

2) I plan to upgrade front and rear suspension eventually. Could I go with a slightly longer travel shock in the rear, such as 7.875" x 2.25"? I get some bob on the Float, so in a year or two I'll upgrade to something more efficient.

3) Front fork. What ranges of front fork travel should I look at, not wanting to change the geometry too much? What has worked for others? The MZ3 is advertised as 100mm, which I certainly don't get, and I'd eventually want something with air.

This thing is just so much fun to ride that I've already been out riding every day since I got it! Thanks in advance for the advice.

The travel on the shock refers to how much the rear wheel moves trough the shocks stroke.

The rear suspension linkage is probably in the neighborhood of 2:1 or a bit more. So for every inch that your shock moves, the rear tire will move 2. So you rear shock has a 2" stroke thus your rear end will compress around 2x that or: 4" travel frame. The fork doesn't make the bike. The frame is the foundation of the bike, so even though the fork has 3" travel...it's a 4" bike. You could get technical and call it a 4x3...or you could just buy a new fork with 4" of travel and balance it out and call it a 4" bike. Either way it doesn't matter as long as you like the way it feels.

No. You frame may be put under stress that it wasn't designed for. Tubes may bottom out on each other etc...
A Fox RP23 would be a good upgrade, but you could save some money and buy a Manitou Swinger 3 way for $99 right now from Santacruz Bikes online store. It has a pretty efficient pedaling platform that would suit your frame. Just remember to get the 7.875x2. You can order the bushings from Manitou or Universalcycles.com

If the MZ3 is adv. as 100mm then it's 4", not 3" as you stated earlier. The last inch may be much harder to achieve if you're just standing over it/compressing it b/c it could be like a bottom-out MCU or something for the "G-out" big hits. I don't know much about the MZ3. A good fork for a blue collar price would be a Rockshox Recon if you don't want to break the bank. The Revelation would be good as well, but more expensive. Both could be purchased with adjustable travel.

My fork of choice would be the Fox 32 Talas RLC. It's light and has adjustable travel as well. The Adj. travel function is nice b/c you can put it at 3" for tame/tight/twisty singletrack and have a snappier handling and more efficient bike. You can bump it up to 5" which will slacken your head angle making it steer slower for the high speed trails with bigger hits. Don't get crazy though. It's not an All Mountain bike.
The RLC version is nice b/c you will have a low speed compression adjustment which is similar to pedaling platform on the Manitou swinger or Fox RP23. Efficiency!

For now, just ride it and enjoy it.

The MZ3 comes in 100 mm or 120mm. What do you weight?

I'm 150 lbs.

honestly, you might not weigh enough to compress that fork all the way. I believe that's a coil fork and it might have higher rated coils for a bigger rider.

No worries unless you are really wanting all the travel.

I ran into that problem in both directions. On most bikes, they are rated for lighter riders and I'll bottom them out. On some (like Marzocchi, they might be rated for a bigger rider).

You take a big enough hit and it will give you more travel. At 190 lbs, I've got a marzocchi fork that I can't get all 80mm out of it when it was coil and after converting one side to air, I STILL can't get all the travel. It's setup right but that coil is dang strong. Didn't have the problem with their air forks.

I disagree about the "no worries" part. (no I'm not a stalker)

An over sprung fork will give you crappy small bump compliance. You will lose traction on stutter bumps and small trail chatter. Your fork should be properly sprung no matter your weight. They make lighter springs.

I'll agree with you on that part. I guess it just depends on how that fork actually rides. Honestly, for the price of new coils vs a new fork....

It's not like that one is high end or anything.

I don't think you're a stalker. Your post wasn't abrasive.

We stalker's appear that way at first

was that you in my garbage this morning?