In my opinion she is far too young to be running those sort of distances, she has at least 6 more months of growing in size and probably another year of filling out and muscle growth, running on hard surfaces especially and continuous limb movement at that age isn't going to be beneficial in the future as she get older.
As a general rule of thumb, puppies should only be walked and exercised for five minutes per month of age, in your case that equates to 30 minutes a day off lead exercise, this is to protect her joints and growth plates in her bones.
Another concern I have of springers being taken for long runs is 'How boring is that for a springer' Springers use their noses constantly, to be taken on a long run with out the real opportunity to meander and do what they're bred for is as boring as hell.
Also, you know when you need to slow the pace a little or get a stitch, how do you you know when your springer is experiencing discomfort, it's not unknown for dogs on runs to keep running through pain and injury to keep up with their owners, what if she is off lead and drops back, you run on not noticing, when you do look back you could find you're separated and out of sight.
I run and cycle too and my view is that walking the dog and running don't go together, it's far more enjoyable to take your dog on a dedicated walk and enjoy the time together with interaction, that's what dogs are for, a partnership enjoying the sights and smells together.
Just my opinion, but even if you do decide to keep running with your springer, wait until she's fully grown at 18 months to 2 years, then gradually build her fitness up and don't forget the warm up and down before the run just as you would do.
:D