Here you go.
https://www.springeramerica.com/
In Dog scouts, one of the things we do is learn to do all kinds of things with our pooches. So far out of all the things for biking the Springer I linked is the best. Like everyone else said you want to work up to distance and or course be aware of climate and terrain and so on, but no harm in doing a mile for a month, then go 2 miles, especially now it is colder and see how it works for you and your lab. Most labs can do a pretty normal pace, a trot, not running but a normal walking, trotting pace for them which would be a casual ride for you. Your going to have to hit your brakes a lot at first and learn to pace yourself.
You want to get a harness that attaches at the top, never use a collar and definitely not a front clip harness. The Springer has an emergency break away in case like the dog goes once way around a sign and you go the other. I would have to look when I get home but we have a great harness for this that allows the dog full range of motion of their front legs I just can't remember who makes it off the top of my head. I will post again when I get home.
In the mean time read some of the guide to doing this on the Dog Scout site. You don't need the badge forms but there is a pretty good guide with a lot of tips.
403 Forbidden No Idea why link says forbidden it works.