I'm a plus sized female (about 135 kg, 295lb, 5'7") from NYC and I'm looking to get into bike riding again. I haven't ridden a bike since I was about 12 years old and I loved it. I'm looking to purchase a bike I can ride in central park or just about any park here in the city. I don't know where to start. All I know is I don't want to pay 700 dollars(531.68 pounds) for a bicycle at this time. What should I do? Is it possible for a supportive bike, I'm concerned about tires and flats. I don't know much about bikes since its been so long but I'd appreciate all the advice you ppl can give me. Thanks a lot.
Since you are getting back into cycling, and have a lot of questions, you may want to find a good bike shop close to you. You can try out different bikes, and they can help fit the bike to you, which will make a huge difference in comfort. Even if you buy a used bike from craigslist, you would likely want to take it to a shop for a proper fitting and maybe a tune up.
As to the type of bike, I would suggest hybrid / city bikes. They allow you to site upright, and are easy to ride. You may also want to consider mountain bikes, since they are widely available used and are inexpensive. Here is a similar question: I am about to buy a new bicycle - what should I check before I do so?
As to your concern about flats, it shouldn't be too big of a problem for you. If you keep the tires inflated to the recommended level (a floor pump is well worth the money), and ride on the surfaces you describe, you should not have any problems. You will still get the occasional flat (it's just a fact of cycling), so be prepared to either patch it or walk home / to a bike shop.
You really seem to have two questions:
1) As a heavier person, what should I look for when buying a bike? This has been handled a couple of times here, but the core answer is to stick with middle of the market components. If you buy low end, the components are poorly made and will break easily. If you buy high end, they will likely be ultralight, and designed for lighter riders and will break easily.
Most bikes you will find in a reputable bike shop will be sufficient. In particular, I would look for wheelsets with traditional 3-cross spoke pattern - radial laced wheels will likely have more problems under heavy load. Something like a "hybrid" or a flat-bar road bike would work, as would a hard-tail mountain bike with slick tires if you are sticking primarily to roads a paved paths.
For more information look at these questions
2) As a heavier person, how can I get a decent bike for under $700? We generally don't give recommendations for specific bikes and brands because that information goes out of date quickly. That said, I would second the comment by Daniel and recommend that you look for a used bike. You should be able to find an excellent used bike that would meet your needs as a beginner for around $500 and likely less.
Take a look at this previous question:
If you decide you really don't want to bother with finding a used bike, I would strongly suggest you go to your local bike shop, tell them the kind of riding you want to do, and tell them your budget. Take a couple test rides, and ride a bike a step or two above your budget to get a sense of what the trade-off in price will be.
Concerning bike saddles :
Sit on the edge of something hard like a public bench. You will notice there are two bones in your butt carrying your weight. Those are your sit bones and are meant to carry your weight. On a saddle you want these two sit bones to rest on the two bumps at the rear. Girls have sit bones spaced more than guys so you should select a girl saddle.
If the saddle is too narrow, it will press on your crotch, and wedge between your sit bones, and that's not comfortable. You will feel this very quickly. If it is too wide, it will rub inside your thighs and they will get sore. Wear cycling underwear, it works.
If your butt is not used to cycling, all saddles will hurt a little at first after 10-20 minutes. So, at first, do not ride for too long. After getting used to it, a saddle that is well suited to you will not hurt at all, however a saddle that is not suited to you will always be a pain in the ass no matter what you do.
Do not choose a saddle that is too soft or plushy. This may seem like more comfortable at first, but your sit bones will sink too much into the plushy foam, allowing the center part of the saddle to dig into your crotch. This is a beginner mistake : it skips the "getting used to it" part (you have immediate comfort) but after say, 30 minutes it's hell.
Also, adjustment is key, if the front part is too high the saddle nose will hurt you, if it is too low you will slide on it and your arms will get tired quickly.
About the riding position :
In the city I don't like race bikes, position is too low to look at traffic.
Dutch-style bikes appear more comfortable, however being too "upright" is not good. First, you have less leg power. Second, when you ride over a bump, your back and your butt get compressed by the shock. With a slightly "bent forward" position, on bumps your back will just bend a little more, absorbing the bump without harm.
About bike geometry :
Test ride at walking pace, some bikes balance much better than others. This is useful in parks with pedestrians.
Normally you'd need to test ride at a very fast speed too, but I don't know if you'll be able to do that.
About the bike itself :
I won't mention specific brands of bikes etc.
If you intend to really use the bike and get some mileage, get some quality components especially in the transmission, all brands (shimano, sram...) have many product lines from "breaks down completely after 1000km" to "lasts more than 10.000 km if properly maintained". The cheap crap actually costs more if you consider you need to change everything pretty often. In Shimano, get Alivio/Deore range, for example.
Since you're heavy, get a rear wheel hub with a cassette, not a freewheel. Freewheel hubs are cheap junk, break axles, and usually have crap bearings.
NYC is pretty flat but maybe you'll want to cross some bridges or go out of the city for a ride.
You are probably out of shape so your power to weight ratio is going to be pretty bad.
So, if you intend to do any kind of climb, you will need some decent granny gears. This is important, since walking to push the bike will kill your motivation.
If you don't want flats, put some schwalbe marathon plus tires, those are not cheap but last forever.
If you want to go shopping with the bike, you'll need a rack and panniers, and a good lock !!!
Anyway. Last year after a long break I resumed cycling. I got a fitness/city bike with a decent granny gear (28T front/32T back), good for climbs.
Result : before -> after weight 110kg -> 100kg and lots of new muscles (still lots of fat to burn though) tired after climbing 150m -> i'm now at 1500 and 150km in a day feel much better now too !
If you do the cardio training part right (get a cheap heart rate monitor) cycling is an excellent way to lose weight and (more important) get in shape and feel great...
I'd generally recommend a "hybrid" or "city" bike. The "hybrid" looks like a mountain bike but isn't really. It may have front suspension (which is NOT a particularly good idea for you) but will not have rear suspension. The "city" bike may be similar to the hybrid or may be a "retro" style like you rode as a kid (though note the latter is often referred to as a "comfort bike"). (The meanings of these terms change over time, and are pretty vague to begin with.)
I'd suggest you not get a single-speed bike (IIRC there are some hills in Central Park) but rather a bike with at least five speeds -- either a geared rear hub or a derailleur style bike. You don't need 30 speeds, though.
Likely the bike you find will be have "26-inch" wheels, which is a slight problem, since you often cannot easily interchange tire widths on a 26-inch wheel. (You can interchange widths on a "700c" wheel, which is the slightly larger diameter wheel commonly used on "road" bikes.) So you should make sure that you get a bike with tires of 1-1/4" to maybe 1-3/4" width (32mm to 45mm). If the tires are in poor shape (on a used bike) or have heavy lugs in the tread you should change them out right away for tires with a relatively smooth tread (rides much smoother and with less effort). And keep the tires inflated to the maximum pressure listed on the side, which will be 50-80 PSI.
(Note that wheel size depends to a degree on how tall you are and how long your legs are. If you're taller than 5-10 or so you may want to consider a bike with 700c wheels, as that gives you a better selection of tires, and often a better fit to a tall body. But "hybrids" with 700c wheels are not as common as ones with 26-inch wheels.)
You will very likely want to replace the seat ("saddle", to the purists), even if you buy a new bike. You should get a woman's seat -- wide, but not the absolute widest you can find. Gel or foam padding is probably good, but don't look for the softest seat you can find -- a mushy seat makes for a poor ride.
And as I said elsewhere, invest about $50 in a good floor pump, with built-in pressure gauge.