Where "downtown" do you live? As I find people around the city use that term pretty loosely, must be a Phoenix thing...

I live downtown and do Gainey on Tuesday mornings, it's nice for the situation you are describing because there are several hard efforts but with the two regroup spots and stop lights you can always catch back on if you get dropped... I think you'd have to be really out of shape to get dropped though. I ride from my condo and it's 47-49 minutes on the nose to get there, 16.4 miles. I leave home at 430 and the ride starts at 530 so I have about 8-10 minutes to fill up my water bottle at the gym, really a great ride too. My favorite in the city.

Saturday is BOS which is the hardest in Phoenix and starts at various times in the morning throughout the year. This weekend is the last 7am start, then April and may it will be 6:30, moving to 6:00 for June, July, and August. If I ride there and back it's a 96mi day so I don't do that all the time.

Both rides are good groups of mostly racers with some other fast non-racers thrown in and then the random strong weekend riders.

Other rides you could easily get to are Tribe in Tempe, starts at the shop on Miller and Indian School. It's two 10 mile loops with the first half of the first one being neutral then it's a testosterone fest. Round trip from downtown this is about a 2 hour ride but it starts in the evening which is gross especially this time of year. You contend with rush hour traffic to get there by 7, ride in the hot, then get home at like 9pm. **** all that noise unless you are a night owl.

You can always meet up with us on Sundays from The Velo at Garfield and 2nd, we do South Mountain as a smallish group and a few of us race, then whomever else shows up. It's a moderate pace to the hill, regroup, then everyone to the top at their own pace, another regroup, descend at their own pace, regroup at the bottom, then neutral pace home. 8am this sunday, then moving to 7 for April.

There are other rides in the area like Airpark, ATM, West Valley, and I'm sure some others, that are relatively "fast" but I think Airpark and ATM are boring because flat ground for a long time with no turns, and West Valley is a total **** show. Inexperienced riders are common, and anyone who tries to tell them what they are doing wrong or could do right is reprimanded because they value how many people are on their ride more than they value the safety and development of riders. It's the buddy-buddy club and they have crashes all the time because of it. If you go on BOS or Gainey and screw up, you're going to get yelled at, and depending on who yells at you, they may crush your soul with their words. This is how I was shown the ropes and I'm a much better rider for it.

edit: I just read the above response, I'd stay away from Silent Sunday if I were you. I always forget it's going on and roll up to the coned off roads and feel immediate regret for riding there. It's very dangerous because you have people thinking they can walk/run/ride/push strollers across the whole road just because it's closed to cars. I can't tell you how many times I've been riding up the hill and some idiot is descending around a corner in my lane or I am going down the hill and go around a blind corner to find 5 housewives walking side-by-side across the whole lane. It's truly awful.