Mongoose tactic mountain bike / loose crank on chain side. How to tighten.Chain ring moves with it. Makes clicking noise.

Loosen rear axle nuts.
Pull back on the rear wheel until the chain is tight, then move forward just a bit and tighten both sides with your hands at the same time. Try to keep the wheel centered.
Tighten the right axle nut, center the wheel and then tighten the rear.
Turn the crank slowly. The chain should have slight play at the tightest point in the crank rotation.
If the chain is too tight or too loose loosen the right nut and move the axle forward or back, tighten and retest.
When tension seems OK loosen left nut and center the wheel, then retest.

I’m happy to help further over the phone at https://www.6ya.com/expert/donald_f2ed37026a3ac881

Its usually a bad freewheel. Its a complex operation to replace, contact local bike shop for assistance

Loosen the nut that holds the back wheel and pull it back until the chain is tight and then retighten the nut. If when the chain is tight, the wheel is not on the rear frame, you need to take a link out of the chain.

this is the side with out the chain ring, it should use a Allen wrench or socket wrench. if this is a mountain bike or road bike a crank arm it usually takes a crank breaker tool to remove arms so if it is loose it sounds like it should be replaced. anyway if it does come off, clean it with any cleaning solution and put grease on the bottom bracket<if you don't have grease you can use Crisco or petroleum jelly> put crank arm back on and then tighten bolt back. this is for a three peace crank, if it is a one peace then its a matter of tightening bolts.

Mongoose didn't make the chainring. They're generic (like most bike parts) and have many substitutes. Determine the parameters and then go looking for one that fits.

http://www.sheldonbrown.com/gloss_bo-z.html

Other parts may also be worn, like the chain.

http://www.sheldonbrown.com/chains.html

there is a spring tesioner but probally need to take a link or two out of chain

That would depend on the style of bearings (loose ball or caged balls vs sealed bearings) and possible bottom bracket damage.

Either way, a Bike Shop mechanic would probably need to assess it for you. Special tools are usually involved.

http://parktool.com/repair/byregion.asp?catid=61

Check the splines on the handle bar. Just loosen the "clamp" and slide the bar over to one side enough so you can tell if the are stripped or not. If they are then replace the bar, if not then reassemble and try to put a littlle extra torque on the bolt.

I have noticed with the 2 of these bikes that I have that the bars do not like to stay tight for long, they tend to work thier way loose about every other time we use them. I just keep tightening them untill the splines strip, then pick up a new bar.

Contact Mongoose for parts info at: www.Mongoose.com under "about" click ask mongoose.

Good luck.

The only way to adjust the "tension" of the chain is to remove links. You will need a chain breaker tool. Shift the bike into the biggest chain ring and the biggest cog of the cassette, then break the chain, leaving the pin partially in the link but far enough out that the chain separates. Now, pull the chain together so that the rear derailleur's arm is as horizontal as possible and aiming toward the crank. Break the appropriate link to connect the chain so the derailleur stays in that position and reattach the chain using the pin you left partially engaged.

i hope this helps
-matthew

I think I can help. Place one end of the chain over the rear gear (doesn't matter which one, the biggest) and adjust the lever or twist ring on the handlebar so the derailleur lines up in a straight line with it. Pull the chain from the rear sprocket down and over the pivot wheel and back over the bottom wheel so it looks just like this S and the end comes forward. Join the chain links. Place the chain over a couple front teeth and turn the pedal carefully until the chain seats on the front sprocket.