4300' climb the week before my first 1/2 IM?

THere is a good chance that this will do you more harm than good.

Performance is a balance of fitness and fatigue. During the taper, the fatigue you have built up from training drops off faster than your fitness does, resulting in an overall increase in performance.

Each person is unique in their response to a taper ad you'll have to keep good notes on what you did and how you felt combined with your performance in your upcoming race.

So I would advise NOT to do a ride of that intensity this close to your goal race.

IMO, doing that ride a week before your race is a very bad idea. No matter how slow you take it those climbs wear you down. No training benefit that close to a race and no way you'll fully recover.

The Sunday before my HIM, I did a 56.5 mile bike with tons of climbing, followed by an easy 3 mile T-run. Then, I had a nice easy taper week. I did not feel any lasting effects the day of the race but as stated above, a long ride the week before a race is not going to gain you anything in fitness. Confidence, yes, but that is about it.

So it sounds like that ride did not hurt you or negatively affect your performance....The real question is could your performance have been higher due to not having the added fatigue from that particular workout 1 week from the race?

Many triathletes have a really hard time with tapering, it just doesn't feel right to them. It takes some faith that tapers actually work, and some experimentatino to see what works best for you!

Monitoring performance with regular testing and tracking is a must in order to see whats working and what isn't. In an ideal training/tapering schedule, race day will be your best performance of the season.