bike intensity in a HIM compared to a full

I've only done one of each, so I'm no expert, but I found that my level of effort for the bike in the Half was at a higher level. The battery in y heart rate monitor was dead just before my Half, so I don't know my zones. I'd suggest doing a hard bike/run brick of perhaps a 2 hour ride in mid to high zone 3 followed immediately by a 1 hour run at your expected race pace for the Half. This should be a good indicator of the impact the harder bike effort will have on your run. My half was before my full. The half was insanely hilly and my fitness was still improving. I did the half as a "fitness test" about 2 months prior to my full. Thus, it was in the middle of my full training plan so I did no taper other than following the "race week" plan for the half distance. Was back on my Full training plan 2 days after the half. Good luck