Bike vs run training time

I’ve done 3, never breaking 12 hours but all below 14.  

Typical for me was ~3000 miles on the bike (167 hours @18 mph) and ~1200 miles running (170 hours @ 8:45 pace) in the 12 months leading up to the race.  BUT...I was doing ultras in addition to 140.6.  

in the 2 months prior to taper, I’d ride 10 hours per week and run 5.  

Were you following a plan?
How closely did you follow it?
Do you feel your bike fitness didn’t support your race goals?

I looked for your race report and didn’t find one, so it’s hard to know how you did or what you might change.  I only have the details of your two posts to work from.  

For me, my race runs were never close to target and bike nutrition might have contributed to my poor runs.  (For sure on IMCdA).

I’d say if your race execution was consistent with your training, it isn’t “fitness “ per se but improved fitness will help cut time out of your race.  I’ll also say train with a purpose which means set your race goals and train accordingly.  If you want a 30 km/hr bike split, you can’t putz along satisfied with 25 km/hr training rides.  

While there isn't a "one size fits all" answer for this, for all of my long course athletes the training duration ratio is typically pretty close to 1:2:1 swim:bike:run (for the record I've guided hundreds of athletes to long course triathlon finishes, both 70.3 and 140.6).  An individual athlete's prior experience may influence the ratio slightly.  In general, you need to swim enough so that you can remain aerobic in the water, ride enough that you are strong on the bike, and run enough to be comfortable running for 4-5 + hours (for 140.6).  If you are going to error, error on the side of too much bike.

You should spend significantly more time biking than running. There are 2 major reasons:

1) Because you can. You can spend a lot more time on your bike stimulating a training response in your body than running simply because it is easier on your body. You don't need to recover from the impact that you get from running. You can put in a lot of time on the bike without impacting your other training or risk of overuse injuries.

2) Because having a great Ironman run is largely dependent on being a very fit cyclist. You need to get off the bike after 112 miles READY to run a marathon. You can't be seriously depleted. It needs to be relatively easy. If it's not, your run will suffer a lot, no matter how great a marathoner you are.

This is true no matter how fast you are. Ive done 4 IM's and maybe 35 70.3's. I'm 43. I'm a 9:50 IM guy and a 4:27ish 70.3 guy (the IM is tough to get perfect!) I spend about 7-10 hours a week on the bike. About 3-3.5 hours running. About 2.3 hours swimming.