Ironman Boulder has a new bike course for 2017. It’s 3 loops of fast rollers, but it’s a bit over distance at 114 miles, so don’t count on a fast bike split even if it is quite fast. There are no technical sections, but there are a few sections that I would call “key sections”:

• Neva Road Eastbound is nice and fast with a great surface. You can take the turn from 36 at full speed and the first corner can be taken in aero. 
• Nelson Road climb is about 4 miles. It’s a grind and you’ll probably have a headwind, but it’s not steep. Maybe 4% grade. Try to stay in aero, especially on later laps when you’re tired – that’s when you need to be aero. Sitting up into a headwind is the worst thing you can do. Having said that, there are some little kickers along Nelson that may be sheltered from the wind, where you can sit up briefly to get some relief from being in aero for so long.
• St Vrain Rd starts with a fast descent and two blind corners, but they can be taken at full speed. However, on laps 2 and 3 this section will be congested so please be very aware of other riders. There is one pothole on the flat section of St Vrain road but hopefully they fix it by race day.

For route maps, here is a link to the route on MapMyRide
Here is a link to the course on Best Bike Split
Here is the GPX file download

Here is a video I shot of the course