hi all. i'm very new to the forum and have a problem. i bought a mongoose from a department store and the front disc dosent stop me it just slows me down, even if i sqeeze all the way. also, i'm hearing a slight rubbing noise from the disc when not on the brake. do i need a tune up or is something wrong, it's 2 days old? thanks mike.

sorry to hear about your bike
disc brakes on low end bikes generally suck, but I have a plan for you;

1. take it back to the department store
2. get a cash refund
3. Go to several local bikeshops
4. testride some bikes
5. Buy a similarly priced new bike if you can
6. If number 5 is impossible, buy a similarly priced used bike.

7. When your new bike has brake or other problems, bring it back to bike shop to fix for free.

Good tips. We don't want to be mean, I'm sure you like your bike but as unsuspended suggested, a bike for around the same price bought from a real bikeshop will be much better along with free tuneups.

Trade it in before the rubbing causes a rash.

Take it back to the store. You'll just end up trying to fix the problem by yourself by throwing more money at it. Visit a few reputable bike shops and see who answers your questions honestly without any hesitation. Make sure you tell them what your budget is and pick up even an entry level bike that suits your purpose. 1 year free maintenance is usualy included, build a good relationship with that shop and come back in a year or so and get a better bike. They will be thankful for the business and you will enjoy not being a full-time mechanic with the dept store bike. Good Luck and Ride Hard!

https://www.bikesrnottoys.com/

That is exactly why your disc brake is rubbing.

What kind of calipers does it have?

wow dept store bikes are coming with disc brakes now lol... they sure are trying to disguise thieir street bikes as mountain bikes more and more.