Cycling both directions right?
Can't speak to Springville road other than the fact that the map at http://www.portlandonline.com/parks/...PropertyID=127
shows that it is at least twice the grade of Saltzman rd.
Often I will leave work at the NW industrial side of town to go home in Beaverslum by way of Saltzman to Skyline to Cornell all the way to Murray.
I'll say that the biggest single danger that I've seen, not seemingly affected by day or night or day of week, is the cyclists bombing down the firetrails with no regards for other trail users: they'll take blind turns (most turns are) at full speed and exit the turn as wide as possible (to increase the turn radius) with no concept that someone else might be using the trail. In the evening dusk, moderate soaking rain falling, >$700 worth of lights blazing, I stupidly expected that no one would be coming down the trail at speed so didn't postion myself defensively. Down blazed two Xtreme Sportz Dudez, mud flying, yelling an amusingly doppler-shifted, terrifying but seemingly sincere "SORRY!". These guys will be even more dangerous on Springville Fire Road.
Skyline is actually quite relaxing if you've ridden downtown. There is a higher concentration of the "entitled road-users" up there who feel that they don't have to share the road no matter what. Odds are you'll be going so fast that you need to take the whole lane to convince them not to pass in the turns. Same goes for Springville rd or any of the other steep descents from Skyline westward.
I stopped going this way in the winter due to the increasing darkness couple with rain making it near impossible to see road debris kicked out of gravel driveways on to the road. I guess if I slowed down below 15mph I could have time to react to the rocks in the road but add the slick pavement and that Cornell is just begging
to be ridden at 40-45mph it just ain't worth it. I've already had my obligatory +35mph bicycle wipe out, I'm not doing that again.