The shortest and probably most popular route to Iron Mountain, as described by Secor, starts at Devil's Postpile Nat'l Monument and heads to Ashley Lake. From there one ascends the "Northeast Couloir", a year-round ice field which requires an ice axe and crampons. There is an easier variation that I haven't seen posted anywhere, which is to take the next gully over. Here I call it the "East Gully", which is mostly class 1/2 with a couple of moves that might be easy class 3. Here's a photo description:
From Ashley Lake, instead of climbing the ice field, turn right and head up the main drainage into Ashley Lake:
Here's the view from Google Earth:
Looking west up the main drainage into Ashley Lake:
Start of the "East Gully" - keep to the left:
Near the top of the "East Gully" - ascend the scree slope, after which you have a short walk-up to the summit:
Add Essential Gear text here.
Add External Links text here.