Sometimes you eat the bear and sometimes you turn around to avoid being eaten by one.
I started up Clamshell Peak north of Monrovia and wanted to get the peak at least, but it was a cold and drizzly day and I turned around at a cloud (see the pics). While I had bear spray, I didn't want to risk accidentally running into a bear or worse because neither of us could see more than a few feet in front of us.
However, the route up to that point showed a good amount of promise. The total hike is 8mi RT with 3,467' of gain, but most of that is in the last 2.5 miles. While it's not as steep as the Lawlor firebreak, it's still steep enough that I had to hold my trekking poles and use my hands a couple of times. I'd gained about 2,200' feet of the amount when I reach a flatish area with an American flag. While I was through the steepest parts, up ahead of me was a solid bank of white and I decided to get it another time.
On the plus side, the drizzle had made the surface easier to descend than I'm sure it'd be after a few dry days. And, doing this on a hot day in full sun would probably not be a great idea. It was cool enough that I only drank 1L of water and that was more than enough.
On the "this is a little embarrassing" (link) side of things, I, after owning this phone for a year or so, only now noticed that it can shoot photos that are four times larger than what I've been doing: about 8000x3600 vs 4000x1800. So, I've been going all these places, spending hundreds of dollars on gas and giving her all she's got, but the ship can literally go four times as fast.
My painful discovery aside, bear in mind that the first 1.5 miles or so aren't as steep and could be biked. There appear to be trees you could use to lock up the bike because you aren't going to make it up the steep parts on it and pushing it wouldn't be a brilliant idea either.
The first .5 miles are along streets because the good burghers of Upper Monrovia are slightly more upper middle class than those further down the hill. They've been able to get the city to require a permit for their streets. Not only that, there are a few signs that indicate, shall we say, a disinterest in hiker riffraff traipsing around in their area. Noblesse oblige implies the nobility.