Mountain Biking - New to actual biking Help please

Currently have 2 bikes 1) Toys R US Equator with mountain tires (1st actual bike bought wayyyyyy back when bout 10 years ago) 2) Kmart bike with road tires (bought few years back)

Well times have changed and sick of tired of dealing with crappy gears and that (especially on the K-mart bike) also sick sick and tired of putting money into these bikes when something goes out (rim was like 30 bucks)

But so my riding will be several different types (basically need an all purpose):
a) Rural Road (some gravel/ so paved [generally flat]) Northwest Indiana (NWI)
b) Some paved trails (slight hills) NWI
c) Looking at doing a bit more off-the-beaten-path NWI
d) Just got a job in Yellowstone National Park for the summer, want a general get-me-around plus some off-the-beaten-path

My budget is 150 and under (I'm collage aged and working fast food till I go out to Yellowstone this summer :) ) so its defiantly a used bike for me

So i'm 6' 1" (165 lbs) and when i went to the bike shop they were like i think a 19" frame but could do a 21" also (looking at Trek)

Trying to look around it looks like a hard-tail should be fine for what I want to do, correct any other thoughts?

Also needs to be quick release for easy transportation (just bought yakima q-tower rack to put on my station wagon on the way out to Yellowstone)

Any thoughts on things to avoid or to get?

Found this

Trek 4900 21" bike $150.00 OBO

This bike is in good working order. It is missing a bolt on front tire (lost during move), and front tire is flat (don't know if leaking) I have not had time to repair the bike so I have to sell it

Thoughts and what would cost be to get a decent quick for this?


Thanks

A new front quick-release "skewer" should be around $10. That's a good idea to look at a quality used mountain bike. However, I've seen quite a few people bring in their prize only to find that it's a Franken-bike cobbled together from random stuff, or has frame/fork damage, or has major issues they didn't know to look for. So if possible, get a knowlegeable bike mechanic to eyeball it before you commit.

Okay thank you does anyone else have any thoughts on it?

what speed would be recommended?

Okay thank you does anyone else have any thoughts on it?

what speed would be recommended?

You can still get drivetrain parts for 7-speed or 8-speed rear ends, as well as 9, so any of those is OK. Make sure to get a decent lock for it. For college campuses, I'd go with a Kryptonite Evolution Series 4 u-lock and make sure to use it effectively (http://www.mechbgon.com/lock).

Given a choice, I'd go with a bike that has a rigid fork (not a shock fork) and regular rim brakes (not disc brakes). That'll reduce the attractiveness to thieves, and may simplify maintenance.

So 7,8, 0r 9 nothing more? and how do you hook all wheels w/ the u-lock? since front is detachable and rear is not?

Personally, I usually lock the rear wheel and the frame with the U-lock, and then use a medium-sized cable to lasoo the front wheel to the U-lock.

About the number of gears, I meant 7, 8 or 9 in the rear. That gets multiplied by the number of gear ranges on the pedal crank (aka "crankset"), so it could end up being anything from 7-speed (1 front x 7 rear) to 27-speed (3 x 9). The chains and rear gear clusters for 7 and 8 are more affordable than 9-speed are.