Esio - to put it into perspective i did regular 15 hour weeks for my first IM with bigger weeks towards the end.
However i had been running for about 3-4years, swimmimg badly for 1-2but biking for 15 years..... i was reasonably fit so coped with the volume ok. I struggled in the last 10 weeks as i started buolding fromn november . Its a long time until the end of june so build into it
If you are a fish/swimmer then do the competitive swim. Otherwise thw beginner program may be more than enough. I found swimming an hour really tiring at first and the fink swims start at 2k++
Start at 2-3 30 min swims and build one of them to an hour. Then feel free to inc another
Feel free to do the competetive bike program. Its tje safest place to add volume of rraining. Just dont get divorced. Also remember thers 28 weeks to go and you want to be puring 10 weeks out not bored/burnt out.
Running. Depends on your background. If you are a novice runner go easy. If you are an ex marathoner then inc the volume a bit so maybe the competeive may be ok.
If you have the tike / enthusism then building the volume up to some big weeks may be ok. However watch the intensity as you do it...(fink does a fair bit of z3,4stuff). hard intervals plus big volume is tough amd you should take your time to get there.
Oh my running zones were about 10 bpm above my biking zones. Long run hr was about 130-145 for me... i eneed up using a mafetone hr for r unning in the end -143 hr cap for all my runs (till later when you start adding in some intervals to that).
Spin classes are ok but riding outside or on a turbo os better. However if its a spin class or nothing then a spin class wins
Im currenlty doing a couple a week (for variation) . Most instructors dont have a clue about biking so ignore the jumps and super slow riding or super fast 'sprints'with no resistance.. If you dont do it on a bike outside dont do it in a spin class.
Keep the resistance high and use it as a fun hard tempo session. Most classes get you riding at 60-70rpm (too slow) as thats the beat of most music so ypu end up climbing a lot. Also feel free to stay seated as most spinnera get bored if they sit more than 2 minutes.
Use a hr and ride at an effort level you want..... ie i use 1class as a tempo keeping hr at about 150ish and hammer the second As an interval session. I normally also do 1 hard turbo session a week as well.
I ususally tack on before/after as indoor riders are unable to ride more than 45 minutes
Re heart rate - google friel heart rate functional tests to set your hr zones 1-5. You need to do 30 min max effort tests in both running and cycling to give you a hr you can sustain for 30 mins (160 is for me) then plug into some tables /% calulations to get z1, z2, z3 etc.
I ended up with a biking z1- 129
Z3 140ish to 155
I did long rides at 130 average. Easy for an hour, tough after 4. Once you can ride long add in z2 sections for an hour at a time.
Remember you are training to exercise for 12 hours plus and you cant do that at a hr of 160.