i am making an assumption here...you live on the northwest side. having said that, you could try White Tanks regional county park. it has several loops so you could tailor make a ride(s). the smallest loop is very easy and only about 2 miles or so long. the next loop is about 4 miles long(bypassing the technical section)the next option, bypassing the switchbacks and tech section, is 5 miles long. if you do both tech sections you are looking at about 7 miles. it costs $5 per car to use the park one day(i get an annual pass for $75).
for free you could try the trail 100 area. T100 starts at 7th ave near mountainview and heads east all the way to Tatum near tomahawk, about 10 miles one way. you can access T100 on north 7th st.(just south of T'bird)and go east or west. there are other trails in the area. or you could access at Dreamy Draw park off Northern, and go east or west. but my favorite access point is 40th st. south of Shea. you can go east or west and there are a lot of trail options besides T100, just do some exploring and have fun. the other thing i like about the 40th st. trailhead is lots of other trail users in the parking lot(so less chance of car break-in)and they have a restroom where i can change out of my sweaty clothes before heading home.
if you would like to meet for a ride let me know. i will be riding somewhere next sunday(busy saturday). i ride early in the a.m. about 6 or so. just P.M. me if you are interested.
p.s. my screen name tells you that i am a bit slow. if you are into speed, well, you will be disappointed.