On Thursday, May 26, 2022 at 9:52:27 AM UTC-4, William Crowell wrote:
> (1) a longer, harder ride every few days; or
>
> (2) a shorter, hard ride done every day; or
>
> (3) some other regimen?
It depends on your goals, "getting into shape" is a bit nebulous. Much of it depends on your specific physiology as well. Some people respond well to shorter interval-style work, whereas others respond better to long steady* distance (aka LSD) rides.
If it's simple weight loss and/or overall health, A balance of long steady rides with some intensity works for most people, thought there is a great deal of research that shows focusing on intensity (HIIT, Tabita, etc) gives nearly the same benefits without the time commitment, especially for a 'recreational' athlete. However, interval-style workouts do require a couple of things: you need to have a healthy heart, and you should have some level of decent base fitness since intense workouts like Tabitas can result in muscle injury if there isn't already some strength involved. IOW, a 60+ couch potato shouldn't be doing hill repeats until they have a decent amount of aerobic base in their legs.
If the point of the regimen is to become competitive, or even just to keep up with a weekend warrior ride, consider using what's knows as a "polarized" approach, which involves ~ 80-90% of ride time in the low aerobic range (~70% LT) with the balance being interval training (over LT). There's also a lot of data showing a "pyramidal" plan works just as well, which throws in some LT work, though the vast majority is still done well below LT.
https://www.trainingpeaks.com/blog/does-polarized-training-really-work/
The point of polarized or pyramidal training is to coerce the metabolic pathways to burn fat at higher intensities instead of glycogen. The typical human has generally 60-90 minutes worth of glycogen but many many hours of fat (even really skinny people). While concentrating on intensity may get you fitter quicker, it will also plateau quicker. The aerobic base work is critical for getting past that hump. Bear in mind that the intensity will burn your glycogen stores faster which leads to exhaustion quicker, therefore if you haven't trained the fat-burning pathway to provide energy for higher intensity levels, you won't last nearly as long on those group rides (If that is your goal).
Given the age demographic of this forum, it would be remiss to overlook the importance of rest and recovery. Your point 2) above might not be achievable given the recovery requirements as we age. I used to be able to commute to and from work everyday. As I've gotten older, I've taken to leaving my car at work and riding home, then riding in the next day. Rest and recovery are _just_ as critical to developing fitness as a regular training regimen.
However, the biggest point of all here is to enjoy the activity. If long steady distance bores the shit out of you, it probably wouldn't be very beneficial and would see more gains in both fitness and attitude by concentrating on intensity. To the extreme, if cycling in general isn't very motivating and you'd rather play Raquetball, then play Raquetball instead. Not only will your fitness improve, but you'll have a better attitude about getting on the bike when the mood strikes you.
*Notice I wrote 'steady' and not 'slow'. "slow" is a relative term, meaning slow for _you_, but it's more important that you maintain a steady pace for these long endurance rides.