When peddling bike seems to try to shift gears

It means its an 18 speed bike. The shifting is easy. Start with the left side, begin riding, keep pedaling, don't stop pedaling in ther middle of a shift, it will throw the chain. As you ride, twist the shift grip, up and back. Still pedaling? Now after you have tried that one, try the other side, its the rear with 6 gears. Up and back, keep pedaling. After you have tried each individually, try them together. And now you're shifting. Looking good
. KEEP Pedaling

the saber zike is a elliptical bicycle. All answers above think you have a motorcycle or they have no clue. Is the chain on the sprocket, It seems to be off the gear. Zike recomends switching 1 gear at a time. Do not go from 7th to first gear in one shift or chain will come off the gear .It happened to me .Chain id not easy to put back on as a bike, that you can turn upside down and have it support itself on the seat and handlebars. The saber you must hold the back wheel off the ground and try somehow to turn the peddle backwards. I am not sure how to make an elliptical chain go backwards like a bike does without resistance.

Matthew, The item giving you trouble is the rear derailler. It works by moving the chain in (closer to the spokes) and out (further away from the spokes) so that the chain can climb onto the next larger or smaller gear. Yours is apparently going too far in when you try to shift to the largest gear. There are a pair of adjusting screws that limit how far in and out the derailler will go. Use this link to find some great repair help. Just click on the derailer on the bike in the picture. Good luck.
http://www.parktool.com/blog/repair-help

Ok, we need to determine whether you have a transmission problem or a clutch problem. Ride the bike until it will no longer shift into third gear. Then stop the bike and turn the engine off. While rocking the bike backwards and forwards, try to shift the transmission though all the gears. If it shifts through the gears there, you have a clutch problem if it will not shift though all the gears, you have a transmission problem.

Please try this and repost with me. I need to know whether your transmission is a five speed or four speed. I seem to remember that those bikes had a four speed that year.

Let me know what you find.

Good luck
Steve

Assuming the drive chain and sprockets are in good condition.(check these first)
This sounds like and internal gearbox problem, a bearing has collapsed or a tooth has broken of a gear.
Riding it like this will cause more damage. The gear box will likely need to be stripped

OK, for a beginner in the world of 18 speed bikes, put the chain on the big sprocket up front, it should be about 46 teeth, make sure it is center and doesn't make noise, if it does, adjust it just a hair either way, now, the rear, put the chain on the big sprocket in the rear, make sure the front didn't start making noise, if it did, adjust it again. You are now ready to take off, in low gear, as you start out, it is easy to pedal, soon you will be peddling air, shift into second gear in the rear only, don't touch the front. Just a little push with the thumb will make it shift, now were going faster, easy peddling, shift into 3rd, then 4th, etc, coming to a stop, down shift the back sprocket back into low gear (big sprocket) and be ready to take off again. Soon you will be shifting that thing like a Ferrari! The front sprocket, will be used for moderate terrain, wheelies, and mountain climbing, that will come later, learn how to shift the rear first. As each gear climaxes, hit the shifter, it will get smoother as you go, and keep the chain quiet, no climbing on the next sprocket or falling out of gear. Hope this helps.

Try this: shift into the highest gear and release the derailleur cable at the derailleur. Pull it taut and retighten the pinch bolt. Give it a thorough washing and degreasing, too. A clean drivetrain is a happy drivetrain. Remember to use bike chain oil, not anything else, on the chain and ONLY on the chain.

Either the shift cable is out of adjustment, the system may need lubrication, or the chain may be worn out. Try some light oil on the chain and shift mechanism pivot points. If it is the cable, try to determine if the bike shifts more easily to a higher or lower gear. Try turning the little barrel adjuster where the cable enters the shift mechanism a half turn counter-clockwise. If that makes it better, keep doing that until it seems good. If that makes it worse, go the other way.

If your chain is still on the rear gears and the front gears on the crank and pedals to easily you have to switch gears into a combination that gives you more resistance. If you are unable to do this while riding, have someone hold the rear of the bike off the ground while you turn the crank and change the gear. You will generally want something in the middle of the rear gears and the second largest on the front to start.

To shift gear properly, while riding the bike you be sure you are turning the paddles, and shift the gear.
Try to avoid shifting gears while riding standing up, this stress the gear system.