Boulder County cycling climbs

According to John Summerson's Complete Guide to Climbing (By Bike) In Colorado, despite there being lots of steep paved grades in Colorado, 6 of the 10 cycling climbs with the greatest length of 10%+ grade in the entire state are in Boulder.  I don't know if that's true or not, but after thinking back and comparing to some of the high elevation mountain passes I've ridden elsewhere in Colorado, I can say with certainty that the steepest climbs I've completed have been in Boulder.  [Aside from a wall or two on Cottonwood, Vail and perhaps Hoosier pass, the challenge on the mountain passes is altitude rather than grade.]  Suffice it to say there are some lung-busting roads around here to ascend, all starting within city limits.  All of the top climbs are featured in the Rocky Mountain Cycling Club's "5 Devils" race year after year (2012 and 2013), which currently seems impossible for my legs/lungs.

So, loyal Boulder resident reader, below I list the cycling climbs from your front door, ranked by difficulty as I see it.

Advanced

require strong legs, cardio and experience

1. Magnolia Road (to dirt) - http://app.strava.com/segments/617452 (pure unbridled masochism)
2. Super Flag - http://app.strava.com/segments/626263
3. Sugarloaf to Switzerland Trail / Sugarloaf summit trail - (from mouth of Boulder Canyon: http://app.strava.com/segments/688595, from Boulder Canyon turn onto Sugarloaf: http://app.strava.com/segments/639707)
4. Super James (to dirt) - http://app.strava.com/segments/764346
5. Lefthand Canyon to Ward - http://app.strava.com/segments/1539

Intermediate

will tax your legs, require stamina and practice

1. Lee Hill east including Deer Trail (to dirt) - http://app.strava.com/segments/725370
2. Linden Ave "all right turns" to Wild Horse (slightly more difficult than Sunshine in my opinion because there are no recovery sections like Sunshine has) - http://app.strava.com/segments/659792
3. Sunshine Canyon (Sanitas to dirt) - http://app.strava.com/segments/666808
4. Linden Ave "all lefts" to Hawk, which does have recovery sections - http://app.strava.com/segments/636163
5. Flagstaff to Amphitheater without Super Flag
6. Lee Hill east climb to horse farm / roller
7. Fourmile Canyon from Boulder Canyon to dirt: http://app.strava.com/segments/822367

Introductory

shortest, beginner grades

1. Jamestown - to town only, without continuing to dirt beyond the town: 
2. Old Stage south: http://app.strava.com/segments/711227
3. NCAR: http://app.strava.com/segments/676117
4. Lee Hill west from Lefthand to Deer Trail: http://app.strava.com/segments/649341
5. Old Stage north

I think the top 5 are in a separate class than the rest.  If you can finish those without needing to stop then you are a very solid cyclist.  There is definitely a jump going from Introductory to Intermediate, but don't be afraid to discover the difference between Jamestown and Lee Hill on your own!

I did not include Boulder Canyon all the way to Nederland because I have no desire to ride it.  Once while sport climbing near Boulder Falls I heard a cyclist get hit by a car.  I think the guy was fine - even though he got carted off in an ambulance - but I have no desire to ever climb this road beyond Sugarloaf due to heavy traffic and lack of shoulder.  In my opinion, it's as bad or worse than Monarch Pass for rider safety.