Altering what you eat will enable you to lose weight. Exercise is fantastic for building muscle, lowering LDL and raising HDL. Great for your brain and many other health benefits as well as helping to maintain weightloss. I exercise on the treadmill and elliptical for 2 hours a day and lift weights for upper body every other day.
When I don't stuff myself, my workout also helps me lose. The trick is to be consistent with your exercise and healthy eating and the weightloss will happen unless there is medical reason you're not losing. But whether you lose or not-exercise is very good for your health.

Your body is a wonderful machine. It will adjust to most things. You build new muscles, your body gets used to them. The greatest energy goes into building new muscles and maintaining the growth, if you don't vary your exercise your muscle growth will plateau. That is what they are talking about. You plateau because you aren't changing things up, and your body doesn't need to change. But Exercise no matter what burns more calories, eating a lower calorie diet will give you a deficit and a result in weightloss.
If you are worried you are plateauing in your exercise then do intervals on your bike, as fast as you can for 1 minute then your normal speed for 2, and repeat for your 30 minutes.
But if you have noticed no loses in weight and think you are plateauing there, then i think you need to address your diet, because if you eating at a deficit you will Always lost weight.

Can i ask how much you want to lose? Because it seems like you expect change to happen very quickly. Your body isn't meant to lose more than 2 lbs a week. Your goal, ideally for lasting change should be 1 lb per week. I know this may be hard to come to terms with, but you may have to work on this for a long time, a year, or two. So make changes you are willing to keep up, and aim for slow steady loss. Eat healthy, exercise regularly, and no matter what Never give up. It took your years to get to the weight you are at now, don't expect to undo that in a matter of weeks.

i weigh 250 right now and would like to be around the 225-220 range

I've also heard that the body gets used to our exercise system and does better when we change things up now and then. Although I think it's always good to do the cardio - we just need to do other things as well. I think Chris Powell sheds light on that in his episodes (can find him on youtube).

Also spiking is supposed to be helpful. I haven't measured results since I started spiking a few days ago but I'm going to weigh in Monday. I warm up for a few minutes, usually 5 and then turn up the speed for 90 seconds and then back down again. I do that a few times during a work out - makes me feel really good. Hopefully, the results will pay off too.

Sounds like altering the diet and the exercise are key. Good luck!! Hope you get some great results. Steady as she goes!

i do interval training 5 minutes regular speed and then 1 minute as fast as i can go, then 4 minutes and then 1 fast, etc etc until the 30 is complete. i have changed my diet considerably, but when i measure my food i am always starving to death and it drives me nuts.

I've read articles about weight training that say there are 3 basic types:

Strength building comes from heavy weights and low repetitions, sets of 5 to 7.

Muscle building comes from medium weights and medium repetitions, sets of 12 to 15.

Endurance building comes from lower weights and large repetitions, sets of 20 and up.

The argument goes that we should be mixing these 3 phases. Some argue changing from one to the other ever week or two is best, but all I've read is opinions and not scientific studies.