Yes, all bikes have a weight limit on them. Commonly, most bikes will have a weight limit somewhere within 200 to 300 pounds. Of course, there are some of you out there who may disregard this rating and ride the bike anyway. If you are a few pounds over the weight limit it should not be too big of a deal. But, if you are a 300-pounder riding on a bike with a 230-pound weight limit, serious repercussions can follow. For one, you seriously risk damaging both the wheels and the spokes that make up the rim.
What happens is the extra weight adds unnecessary stress to the bike and the first aspect to usually suffer from this will be the wheels. Given you continue to ride the bike after the spokes begin to break, the bike will eventually collapse as the core strength is being compromised.