Originally Posted by JamesAA .....So what's a good HR zone to stay in and for how long should I be cycling? ...Also, what's a good recommended plan per week? ...
I'd turn those questions around and it should all make sense. IOW, pick a training plan that fits your lifestyle and addresses your cycling goals, start there. The plan should give you training goals for different days of the week with some harder and or longer rides and some easier rides or complete rest days. When you've figured out hard you want to go on the harder days then set HR or RPE targets that are sufficiently hard but don't totally fry you and on the days you plan to go easy just glance at the HR monitor to make sure you're not turning easy days into hard days or even easier just tune into RPE and make sure easy really is easy on those days.
If you have particular cycling goals like long organized day tours or particular types of races then craft your overall plan to target those goals. If your goals are more general as in better overall cycling and life fitness and the ability to go longer or climb some bigger hills at a good pace when the opportunity arises then it can be simpler.
Regardless, try to ride most days as in four, five or six days per week. Try to make cycling part of your normal lifestyle if it isn't already so think about things like bike commuting or running easy errands around town on the bike. Make some days harder and longer and some days easier and pay attention to your body in terms of rest, recovery, excessive soreness and things like unexpected bad moods and back it down if you've been going after the training a bit too hard or a bit too frequently.
Many weekly plans arouund the internet targeting century rides, road racing, triathlons, time trials, cylocross, crits, you name it but they're mostly going to come down to ride a lot, ride most days and focus your harder efforts into two or three days per week, ride a longer day or two per week at more moderate paces and take a verry easy day or two and perhaps one day completely off the bike.
If you're not clear on the demands of specific events then focus on sustainable power or FTP in power terms. You don't need a power meter to focus on that just do the training. For more on that and for someone with a 9-5 job search SST (Sweet Spot Training), FTP training, 2x20s and other related terms on these boards and on the internet. And read the first hundred pages or so of the classic 'It's Killing Me....' thread to get an idea of how to proceed with focused SST/Threshold training.
The HR you held that you could only sustain for about 45 minutes sounds like classic SST or low Threshold pacing. It's not easy and you can't do it all day and wouldn't want to try it every day but it is very effective in terms of improving fitness and raising your FTP and overall sustainable power when done on appropriate days in blocks of 20 to 60 sustained minutes.
Good luck,
-Dave
