What is a decent replacement rear derailleur for a Mongoose 26" Ledge 2.1 Mountain Bike?

I had a look at the Mongoose website.
They have manual for download.

https://int.mongoose.com/pages/product-manuals

Enter the model of your bike, or look for a picture of it.
Follow the instructions....

REgards
Geoff

A replacement can be purchased on ebay or amazon or your nearest bike shop. They can also help you install the new part

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

Any Shimano rear derailleur that is specific to the amount of cogs you have in the rear will work. Alivio is the entry into the nicer derailleurs. The more money you spend, the nicer they get: lighter, more machining, a more precise fit of parts.

Change the spring to your load.

Adjust Mozo M30 Fork Suspension - Beckman Du-70 Forum

efratoium.xyz/Adjust-Mozo-m30-fork-suspension/

Results 1 - 15 of 15 - Mongoose XR 150 mozo m30 front forks rebuild. A quick ...Mongoose mozo m30 forks are sponggy on my XR150 mongoose mountain bike.

mozo??- Mtbr.com

forums.mtbr.com/shocks-suspension/mozo-167281.html

Feb 20, 2006 - 15 posts - ‎6 authors
... of a mozo m30? is it the junk im assuming came on my mongoose? ... into a halfway decent bike. and all i can get off the fork is mozo m30 ...

Mongoose XR250 Suspension Upgrades ' Bicycling Magazine Forums

forums.bicycling.com/topic/54635607127666779

You have a 21 spd and you have two derailleurs, one front and one rear. To shift you must always be pedalling forward, not backwards or you can chip teeth on your chainrings and cog. To shift, remember left hand controls front, brake and derailleur, the front derailleur is what gives you the ranges, gears closest to the bike are the easiest, so, small ring it the front are your easiest range, middle, mid range, large hardest but fastest. It is best to remember that it is the number of teeth that are hitting the chain to give you the speed you want. Rear Derailleur is your fine tuner the largest is the easiest, same as above. NOW DO NOT KITTY CORNER YOUR CHAIN, SUCH AS LARGE COG IN REAR TO LARGE IN FRONT CHAIN WHEEL, AND DO NOT USE SMALL IN REAR TO SMALL IN FRONT CHAINWHEEL. The reason you do not do that is: you can stretch your chain, yes you can stretch your chain and it serves no purpose, if you are pedalling to easy change your range(front). I hope this helps you understand how to shift now. You may contact me for any further questions, I have been in business for 38+ years

You mean rear derailleur? It all depends on what needs fixin'.

Browse these:

http://www.sheldonbrown.com/derailer-adjustment.html

http://parktool.com/repair/byregion.asp?catid=53

and then decide if it's within your range of abilities and tools.

http://www.amazon.com/gp/product/images/B000B8IDS2/ref=dp_image_text_0?ie=UTF8&n=3375251&s=sporting-goods If it has a Shimano Altus rear derailleur, you can look here:http://bicycletutor.com/adjust-rear-derailleur/comment-page-3/ or here:http://www.parktool.com/repair/readhowto.asp?id=76

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.

A special sprocket removal tool is required usually only $20 to $30 bucks at a decent bike shop.