Before each ride I do a quick safety check:
- Brakes adjusted correctly
- Handlebars correct, wheel in line, headset tight
- Saddle/seatpost tight
- Pedals and crank look good
- Chain looks good
- Wheels true (maybe not perfect, but quick spin shouldn't show huge
wobble or brake rub)
- Quick Release Tight/Hub Nuts Tight [thanks Kibbee]
- Tires inflated
With the exception of the "tires inflated" this takes me about 30 seconds. The "Wheels true" I do by just spinning the wheel and looking at distance to brake pad. After first revolution I can stop wheel where I need to align stem for easy pump.
"Tires inflated" I do by hooking up the pump and topping them off. If I had a flat on the last ride, I let out the CO2 and replace with air, otherwise I just take them back up to whatever pressure I use for the particular bike and conditions.
This list is also the list of things to NOT wait to find out before fixing.
On a new bike, you will also want to adjust for cable stretch on the derailleurs during the initial period. Many bikes have barrel adjusters that make this simple, but looking at the close up pics of the GMC Denali, it looks like this bike does not. Simply put, the lower priced bikes are able to be lower priced in large part by making assembly cheaper and using parts that are cheaper to make. This is NOT to say that it's not a very serviceable bike. Most of the tradeoffs just make it a little bit harder to maintain. The two that affect adjusting cable tension are the lack of barrel adjuster and the use of a regular nut rather than a hex bolt to hold the cable.
You can make the same adjustment, you just have to use a different tool. First, don't worry about this until your shifting starts to get a little bit sketchy. Once/If it does, you will want to shift to the smallest cog ( rear gear) for the rear derailleur. Then loosen the nut holding the rear derailleur cable and just pull it "strong finger tight" and retighten the nut. If this doesn't help there are easy ways to work through it, but come back and post another question so we can make sure we talk you through it.
The front derailleur generally isn't quite as affected by stretch, but if it becomes harder to get into the bigger chain ring (front gear), do the same thing...shift to smallest chainring and loosen nut, tighten cable, tighten nut.