You'll do better if you mix interval work with long, steady riding.
The advice about interval training and weight loss is fairly new and possibly controversial, but as interval training is good for your general cycling anyway, I'd include it. You don't have to be manic about it - in my case, I have a very undulating ride near here and by going up and down those hills, I'm given a quasi interval ride. Not the real thing sure, but it's a more interesting ride than staring at a computer and those ruddy hills have to be good for something.
The long, slow ride should be well within your aerobic range and that heart rate depends on you own personal max and your own body. It's been discussed before so we probably don't want to go into it here.
Frankly, the thing against training on your bike is the length of time needed. You talk about various distances, but unless you are unemployed or have no family responsibilities (try being a single Dad for restrictions), you're going to have trouble finding time to do humungous distances.
Now, for me
My trial in the Family Fraud has been put back ... again. That's what's kept me from being too serious up to now (emotional stress isn't conducive to stuffing about with training regimes I'm afraid), but at the moment, I'm in the mood to put put some effort into my own weight loss so I'm going to set myself up into a program.
Looking at my life realistically, I'm not going to be able to commit to more than an hour a day, every day.
So, my base ride will be an hour ride. As these are relatively short, I'll make them 'interval' rides, along my hilly route. I'll work out some mix of how hard I push them - some days a lower effort than others.
On days when I can't ride (usually when I've got the lass with me), I'll do half an hour on the stationary bike, aiming for an hour but I know how the boredom hits. So, realistically, I'll do a minimum of half an hour with a cadence over 100 and a heart rate around 140.
Wednesday nights and friday nights, my son has soccer training. This gives me an hour and a half for a ride. Wednesdays will be a definite though with daylight saving ending, I'll no doubt be reviewing my lighting. The fridays probably won't happen - for one of them, I'll have my daughter with me (and you don't ride at night, in winter, with a 6 year old on the tag along - sitting in the car with a bucket of chips works though) and on the alternate friday, my girlfriend has shown a tendency to want to see me, it being the only evening in a fortnight we get on our own.
Once a fortnight, on the weekend when I'm bratless, I'll do a 'long' ride - 70km +. I'm aiming for 100km - the trick is finding a decent route.
So, I'll aim at an hour a day minimum - hilly terrain ie interval work. I can mix these up with the fixie - that is a far more intense ride than the geared bike so even on a flattish route, I'll get a good workout.
Once a fortnight, a long ride - taken at an aerobic pace (under 140 where practical).
Once a week (wednesday night), an hour and a half up near my lactic threshold (140 - 150).
If I can sneak longer rides in during the week, I'll try to make them in the 'fat burning' range (130-140 for me).
Half hour plus on the trainer any day I hit the streets.
BUT, I'll also have one day a week off the bike to recover.
If I've worked hard the day before, I'll take the next day quietly eg, after the 'long' ride, I'll do a recovery ride - on the flat and low HR.
Diet wise. The red vino will be cut back but not given up - realistic goals are what I'm looking at, not something an olympian will aspire to. I'll serve myself smaller serves even if that means wasting food - at the moment, the lad and I tend to eat everything cooked (with a portion frozen for reheated meals) and that means that sometimes I over eat. My diet isn't bad otherwise and I'm not into lollies and snacks and things to any silly extent. Those first two changes will do for a start and once I've got myself sorted and had a chance to review the results, I'll be having a chat with Mike about other changes to make, but I may not need them. At 50, I won't get skinny in a hurry so all I'm looking at achieving is a decent look in a cycling top.
So that's me. Thoughts and suggestions are welcome. Remember, I'm trying to fit a regime that'll help into my lifestyle and am not in a postition to take up a full on training regime - being a single parent means you can be restricted after school (no-one to look after the shop while you're out), even with a 14 year old. Getting a job will affect things too, some money to spend for starters and a chance to commute (which I reckon is one of the best fitness devices ever invented). I know this post is long (so Tuco hasn't read it), but I reckon that by sharing our thoughts and patterns, we get a better insight into how to fit cycling into our lives and to be honest, that's what it's really all about.