Major brands out there right now with entry bikes are Felt, Fuji, Giant etc. But what is your budget? If you are looking for a $200-$300 bike, go for a 1990's Trek, Cannondale, or Schwinn. It may be used, but it will have good components and won't break the bank. For under $200 you're looking at an older 1970's or 1980's Schwinn type of bike. These are easily modified and any bike mechanic should know how to work on these. Look on your local Craigslist.com for used bikes. Also, bikesdirect.com isn't a bad site and has bikes for every price range. I've been told the bikes for sale on Walmart.com, Target.com and Amazon.com are a lower quality bike. That means you'll have to do tune ups for frequently, and depending on your training, you may have to replace some of the bearings or crank sooner than a more expensive bike. But first things first. Set a beudget. Then remember if you want clip in pedals and shoes that will cost an extra $100-$200 dollars.