Sunrise & Sunset: Beautiful but potentially dangerous

Riding under stunning skies at sunrise or sunset is inspiring and makes for great photos. If you are riding at this time, odds are part of your ride also happens during the time when the sun is low on the horizon. There is an insidious scenario that can turn certain parts of your route into a danger zone. Here's the recipe for danger:

1. Riding on a road shared with cars, especially when there's no/minimal shoulder space
2. Sun low on the horizon (and the horizon itself is low, minimal terrain above the drivers line of sight)
3. Clear day. No clouds to block the direct sunlight 
4. Road lined up with sun such that it's in your eyes (and even worse, in the eyes of drivers behind you)

Combine these elements and your normal commute road becomes much riskier. The blinding sun is probably an annoyance to you personally, but the real problem is behind you. The automobile drivers, who are likely ~90% less "inspired" and attentive than you on the bike, are going to have a hard time seeing you in these conditions no matter how much you might be doing everything right -- blinking tail light, reflective clothes, staying to the right, etc. Direct sunlight is no match for any of that, and often drivers are going to try and avert their gaze to avoid getting blinded, meaning that you are even less likely to be seen. 

So what are your options?

• Switch up your route. For example, I often will roll west on Bay Street at Fort Mason in San Francisco once the right-hand lane and shoulder turns into parking after 6pm. However, depending on the time of year this stretch has all the elements of danger noted above. When all four conditions are present, I bail out and take the slower mixed-used path through the adjacent park.
• Switch up your timing. Once you get to know the possible danger areas often you can avoid the worst of it by shifting your timing plus or minus 15 minutes. 
• Be extra cautious. If you are caught in this situation and don't have an option, you should consider some extra steps to increase your safety. This could include: waiting for traffic light timing such that there are fewer cars on the stretch of road, or even going deeper into the shoulder even at the increased risk of a flat tire.

For the curious: this paper looks at a few hot spots in Colorado and does a really nice job trying to quantify severity based on sun position relative to drivers viewing angle. There are some pretty stark results suggesting that sun glare is the leading cause of accidents in some of the hot spots they analyzed.