MTB trubles

Look at the small sprocket closest to the axle of the two sprockets on the rear shifter mechanism. See if it lines up exactly with the sprockets on the wheel. If it doesn't, then that might explain you hesitation of gear changing. To line up the sprocket even with the ones on the wheel, you can turn a knob at the gearchanging thing on the handle bars where the cable goes out or where the cable sheath ends at the gear shift in the rear. You have to experiment to see which way the gear shifter will move when you turn each knob to make sure the sprockets line up.
Now, for your no 1st or 7th. There should be two skinny, long bolts on the rear gear shifter, they control when the gear shifter should stop so that the chain doesn't fall off 1st or 7th. Maybe they are too far screwed in and stop the gear shifter early. So try to study them and see if this is the case, if so, then just loosen the bolt until the gear shifter can get into 1st or 7th, whichever it wont go onto.
Best of luck, they are a pain in the arse.

ok...now I don't know jack about these MX bikes, but in this field of MTB I can help..haha.
Glitch is right on track with telling you what to do! I'll just give a few more pointers..... Has anything ever hit the "actuator" (real name deraillure)? If so the part of the frame that it (deraillure) hangs off of (deraillure hanger) could be a little bent, which is not a big deal, but if it is you're kinda fighting a loosing battle. Local bike shops should have the tool to make sure it's alighned properly. Or you might even have an replaceble deraillure hanger, which may be loose and just needs to be tightend up, or replaced.

1>If it's straight then start here to readjust it from a fresh start, first shift the deraillure into the smallest size gear on the cassette (the cassette is what all the gears together are called)

2.Now that you are there you can disconnect the cable from the deraillure.

3.Once that is done do not change the shift lever on the bar! Make sure it stays in that gear.

4.Now that you have done that take a look at how the deraillure pulleys lines up with the smallest gear. it should be just about inline with the smallest gear, could even be a mm past it towards the outside and it would be fine. You just dont want it to be a few mm towards the next gear.

5.If it doesn't line up. There are those screws as Glitch stated, you need the one labled "H" for high. Turn it in to make the deraillure move in, or turn it out to make the deraillure move out.

6.Now if that is all lined up you can then go and re attatch the cable to the deraillure. Do this by taking the barrell adjuster ( the plastic nob on the shifter and deraillure) turn those all the way in. Then turn them out about 1-2 turns. This allows you adjustments to either tighten the cable or loosen the cable without tools.

7.Pull the cable tight and then tighten it down to the deraillure.

8.Shift it up one gear, if it's to slow, then turn the barrell adjuster out to tighten the cable. Keep that process up until it shifts into the next gear.

9.Once that is done, shift it through each gear, but only one gear at a time, so that you can see how it shifts to each gear. If it's still slow turn the barrell adjuster slightly more until it shifts up to each properly.

10.Now finally if all the gears shift fine, and then you get to the biggest gear in the back and it doesn't want to shift into it you need to adjust the "L" screw on the deraillure turn it out so that the deraillure can move out enough to get into that gear. If the chain falls off, then turn the screw in to stop it from over shifting.

I hope all this helps you out a bit, if you need more help just ask!

Where exactly does it hesitate? Like when you shift to an "easier"/bigger size gear or when you shift to "harder"/smaller size gear? Have you ever chainged your chain lenght?

There is also a small screw on the deraillure that adjusts how much tension it puts on the chain itself. This can slightly adjust how it shifts, because as you move the pulley's away from the gears the easier it is to shift, but then you may run into other problems as in there isn't enough chain rapping around the gear...or other small things.

If you turn the screw in it will pull the deraillure away from the gears, turn it out and it lets the deraillure move in for less tension and gets it closer to the gears. This screw is on the bottom of the deraillure almost right where it bolts to the frame.

If there is hesitation it could also be that if you have a replaceble deraillure hanger it's loose and just flexs under the extra torque/power in those gears.

Honestly the hesitation is a bit harder to diagnose without having my hands on the bike and looking at it. There is a cool forum for mountain bikers, but I don't know if anyone will get mad if I put it up here...dont' want people to think I'm spamming in here.

So check out those few other things and see what happens. I'm more than happy to try and help you out as much as I can. And maybe someday I'll have some questions that I can't figure out on my MX bike and you'll have the answers....haha. Man these things with motors....crazy I tell ya!

Man to bad I didn't talk to you 5 days ago, I coulda hooked you up with a smokin deal on a mountain bike. I work at a shop, and we have a few bikes from last year I coulda sold you at pretty much our cost. And it woulda worked right, cause I would have worked on it...hahaha! Good luck with it. And if it still doesn't work right I can try and help ya some more, even get pics to help you out if need be.

if you're still looking for a mtb i got a few in my shop (brand new) I could sell ya cheap! Ya BMX bikes are a blast I got two I ride, street and dirt. I like MTB's more though....especialy DH rigs, DH is a completely different world! But I live where there are no hills so I guess I wont be ridding DH anytime soon....haha.

Well even if you need some pointers on some good bikes let me know I can help ya out too. Good luck!

No offense, but the bikes you buy a walmart and Dicks are kind of cheap. Go to a real bike shop and buy something that suits the type of riding you actually want to do. Not only will the bike be better but the mechanics working on them will be much more qualified and fix it Right.

Ok, a little inside info for you. Yes mongoose does make a pretty good bike. But there is a difference between the mongoose you find at a "big box" store (a non bikeshop store) and one that you would find in a local bike shop. You have mongoose and mongoose pro, two different bikes. The pro is the better of the two. So don't get fooled by the name you see in the big box stores, it doesn't mean it's the same bike that's in your local shop. You can still get a bike in a shop for about 200 bucks. Look for a last years model, or they do have base models at the price range you are looking at.

Most MTBs under $500 won't handle much hard use. I know alot of people can't afford what would really be considered an entry level MTB. The componantry on the $500 and up bikes are much better quality and much more durable. The first two MTBs I owned were sub-$500 bikes and something was always messed up. I finally saved enough to get about a $750 bike and most of those problems were a thing of the past. The componants stayed in adjustment longer and lasted longer. When it comes to MTBs you basicaly get what you pay for.

 

Steve