RR#2--IM CDA--On site bike ride/run
Race Rehearsal--On the IMCDA Bike Course 
Met up with an old classmate who did IMCDA in '08 and is doing it this year again.
Nutrition: Aero bottle with water, Water-Bot with Hammer Gel and Nuun tablet, bottle with 400 cals of Max Muscle stack, Bite-sized Snicker's.
Headed out at about 8am, a little chilly in the morning so I wore spandex leggins and a long sleeved cycling shirt. Kept the pace pretty relaxed for the first loop. Conditions were pretty good. Not much wind, the temps were great and the sun just right.
I managed to fall over on my bike at one of the busy intersections on Government Way. 
At a stoplight I unclipped the right shoe, but leaned left and down I went. How embarrassing.
Got to the Hayden Golf Club and then the hills. Luckily I have been training on some hills north of Vancouver and these hills didn't seem much different--they hurt about the same. I took it easy and emptied just about every bit of my nutrition on the first loop. Finished first loop in 3:38.
Grabbed a banana, refilled bottles and headed out again. Our goal was to negative split the second loop. Kept a good steady pace the first 20 miles or so. Once we got to the hills along Hayden Lake, "oh my gosh!" These hills feel much different the 2nd loop than the first. I struggled up most of the hills, my buddy just motored on up and I was really lagging behind. But I kept my HR and perceived effort steady and tried not to spike anything.
Stopped at the IM training aid station at about mile 88. I was needing to refill my water bottles, but there was none to be had.
Ugh. Okay, I've got just a little bit left in my Max Muscle stack, nuun bottle and nothing left for water. I filled up a little with some Gatorade they had on site and pressed on.
Shortly thereafter, the pain started in. About mile 90 I was really struggling up the hills. My buddy said, "3 more hills." His count was off by about 4. Finally got through all that and pointed back into town. I couldn't wait to get back. All of my aid was gone and my legs were really tight.
Finished the second loop faster than the first at 3:36. Total time is 7:14. Grabbed a banana and some water, put on the runners and headed out on the run course.
Initially the run was pretty tough, but after 20 minutes I loosened up. We kept it really easy at about 10:30-11:00 miles. I was doing great, getting a little tired, but still chugging along. At mile 3 I needed to use a porta-john and once I got inside the world started spinning. I almost passed out. I don't know what was gonig on, but I suddenly felt like crap. I got out of the porta-john and had to sit down. I took a gel and some more water, but things just weren't right. I started feeling nauseous. I decided to call it done right there. My girlfriend was with me riding her bike, so she went back and got the truck.
So what the heck happened? I think I didn't take in enough calories nor fluids on the bike. I probably pushed it a bit too much and burned out one too many matches. The run was being executed just fine, I thought. But now I can't fathom another 23 miles feeling like crud.
Question: After coming off the bike and wanting to keep the pace really slow the first 45 mins or so, what is the thoughts on walking this part and then start running?
Comments
@Mike
Seems like you were under nourished on the bike. 300 calories an hour would be on target, but not sure you had that much. Keep in mind that you went into this RR not rested and carrying lots of accumulated fatique. That being said, unless you were able to look at the color of your urine and look at HR charts hard to know what went wrong. I have done CDA 3x on the new course and having just moved from there and ridden the course probably a 100x I can tell you the 2nd lap is way tougher. There are harder bike courses on the circuit but I feel strongly that the timing of the hills in the whole of the race make this a tough course. Those hills at miles 95 and 100 right before finishing the "hilly" section really cook folks.
Not knowing your goals, walking the first 3 miles and really getting in some nutrition might not be bad idea. You could the go 3 miles at +:30 and then see how the running feels.
Concentrate on what you can manage and it will work out.
@ Mike:
My personal plans as a heavier slower runner are to pick a pace from the pacing charts for IM. My current vdot is 46 - but that is based on a 5k. I figured that in reality I ran at 88% of a vdot of 42 for my last HIM (vdot was 43 at that time) and missed it by a few seconds per mile. My best long run pace is 17.5 miles at a 8:43 pace a couple of weeks ago.
My plan is to aim for 75% of a vdot of 43 for IMCDA. This ends up being a 10:20 pace ( a lot slower than my 9:07 EP from vdot of 46). I plan to execute this with a 10:50 pace for the first six miles. During the race rehearsals I walked for at least a minute for the first couple of miles. I figure this will put me in at about a 4:34 marathon. If I feel great at mile 18 I can increase my pace - hopefully sub 10' per mile.
Just my own plan - but based on conservative estimates from the Long Course Race Execution talk from RnP.
Tom
Another thought to latch on to what Bryan said:
I think nutrition and hydration are the key. If these are neglected no amount of fitness will overcome nutrition or hydration deficits.
Tom
Mike - in addition to what I posted to this report on another thread:
There is a complex equation in the ironman which involves a number of variables: bike effort level and variability, hydration status at the end of the bike (calories are less important, but a minimum of 11-1500 are needed), and environmental conditions - temperature, sun vs shade, and humidity. The whole trick, I believe, is to go as slow as you have to at the start of the run to keep your hydration status in good shape for the first 60-90 minutes. That means, of course, starting the run well hydrated, so drinking on the bike is critical. And it means making sure there's adequate blood flow to the GI tract to allow fluid absorption. The hotter it is, the more blood flow is shunted to the skin to cool the body, so the less available for use by the muscles and the gut. The gut should be your priority for those first 6+ miles.
My conclusion: go whatever speed you have to to allow you to take in the amount of fluid you need during those first 1-1.5 hours. If the temp is 66 and it's overcast, you may be able do that going your LRP + 15-30 sec, as well as walking each aid station. If it's 90+ and sunny, you may need to go 2+ minutes/mile slower. If that means walking more, so be it.
From then on, if you want to keep running, you will have to put up with slowly getting dehydrated and behind on your calorie needs. I think it's very important to have a very clear understanding of your "sweat rate" (fluid needs) at baseline, which is that mid-60s, no sun situation, and then add to that as needed for environmental conditions. You also have to be cognizant of when your gut is not absorbing what you're giving it, and decide if that's because you are running too fast, drinking too much, or a little of both, and be willing to slow down one or the other or both as needed.
For me, those numbers turn out to be 6 ounces per aid station baseline, up to a maximum of 12 ounces per aid station. And I calculate 1 sip = 1 ounce. Less than 36 ounces per hour, and I fade too fast; more than 80 ounces per hour, and I start to slosh, no matter how hot it is. After about 82F, I need to start to slow down significantly, just to absorb what I need. YMMV, but there's still time to come up with your own personal formula.
Circling back, this whole plan ONLY WORKS if you are topped up in fluids at the end of the bike, meaning that you have been drinking a steady amount throughout (maybe a little easy on the intake in the first 1-2 hours, as it is cooler), NOT guzzling 3 bottles in the last hour.
So to answer your Question: After coming off the bike and wanting to keep the pace really slow the first 45 mins or so, what is the thoughts on walking this part and then start running? It all depends on your hydration status coming off the bike, and the weather conditions at the start of the run.
Good luck!
P
Thanks for all of your support!