If the cycling commute is flat, it has to be long to get decent exercise, because you have to apply a flat-out effort and you cover a lot of ground. If my bike commute were flat, I'd prefer to be some 14 miles from work rather than the current 7. Or else I would have to run it (more often).
To me, what would make an area ideal for cycling (if it has good roads and such) is: dry climate. No rain, no snow.
I'm Dutch. The Netherlands is one of the most bicycle-dense countries in the world, and we have a, well, less than ideal climate to say the least. Rain, wind or snow really isn't that much of an issue when you have the right outfit.
But cycling commute isn't about exercising, it's about commute. I live in Stockholm, it's cold, it's wet and not as flat as Berlin, Copenhagen, Amsterdam, etc., even then I bike to work even during winter because it's fun and a good way to get around the city, the exercise is just a bonus for me after biking 30+ km in a day because I had to go places.
I'd say that cycling is an ideal way of burning fat. With a bit of training you can easily spend a whole day on a bike without risk of overuse injuries.
Most people exercise at a relatively high intensity which mostly burns carbs. Great if you want a cardio workout. Not good if you need to burn fat.
As someone who gets repetitive strain injuries from running and isn't a great swimmer cycling is a God send. I can go biking 7 days a week. If i need a blow out then i push a harder gear without dropping cadence... Or i do tabata.
You can burn 700-800 calories riding for 20 miles or about 1 1/2 hours.
I wouldn't walk that much (hours of walking) or run that much (a lot harder on the body), so to me it's really great exercise.
That's also why I find kazinator's post a bit exaggerated. That dude's burning through a lot of calories every week. You can eat a lot of ice cream (personal experience) and still lose weight if you're doing 14 miles every day.
Not denying that moving limbs is good for you! I also love cycling, which is a very important factor. I'm just saying that minute for minute, you spend more calories on inefficient modes of transport such as running or swimming or rowing or lifting heavy junk, so if your primary concern is maximising exercise in as little time as possible, that's the first place to look.
My bike commute is only 5km one way, but it helped me a lot losing 10kgs of weight and developing good overall fitness and even some visible leg muscles. I try to go at a fast pace though, i agree that when you drive normally there is not a lot of effort involved on a 20 minute commute.
7 miles isn't much on a bike, but anyone riding 14 miles 5 days a week should be in great shape.
14 mph is a decent clip, whereas 20 mph is constant exertion. I'd hate my commute to be a hour long both ways and at 14 miles, that's what the average person is going to hit.
Do you mean 10lbs of fat? If that's the case, watch your diet, 10lbs in 12 weeks you are eating something averaging 370kcal above your needs per day, with biking (and assuming you are a man and don't do any other kind of workout) it means you are eating between 3300-3800kcal/day, that's a lot if you don't do hours of sports or heavy weightlifting.
Not sure, but I was mostly joking. I mean, it was true, and my diet had not changed from when I was more sedentary, but I've ratcheted things down quite a bit since then with careful meal tracking and even more exercise (130mi/week on the bike, 18 mi/week running, plus strength training and core training).
ride a heavy fat steel bike with both front and back suspension and low tyre pressure and tyre treading for slowing the speed. Sit upright and keep the seat position low for inefficient pedalling.
To me, what would make an area ideal for cycling (if it has good roads and such) is: dry climate. No rain, no snow.