I'm no expert on training dogs but I have always had a herding type dog growing up and am used to the level of ability and activity that comes along with them. We did do about 6 months of agility classes with him when he was about a year old and we did lots of just riding around the yard with the bikes well before we took him places. I didn't take him out on the trails until he was close to a about 20 months old and we were confidant that he would eventually recall to us as his recall at 2.5 years is still only about 95%. I'm still trying to teach him how to follow the bike, but he just realllllly likes to lead be it riding bikes or just walks. He has figured out that when we are going slow up hill that he should stick closer and mostly heels with the bike. Otherwise he mostly sticks about 20 yards up trail and stops and checks on me fairly often. But mostly I think I've been blessed with a dog that picks up things super quick and thinks of biking as one of his "jobs" and thus tries really hard to do it right for me.
I would try to get the position commands done on foot indoors first, then move outdoors on foot, and finally add the bike in before even trying to go to the trails. Do remember that your pup needs water and food just like you do. I carry extra water in a bottle for him and bring extra in my hydration pack just in case. Second is that, they don't tend to listen very well for the first mile and then settle into the rhythm of things after that. Start small and work up just as you would when you are starting your riding season. Powder and I kept it to 2-3 miles once a week for most of the summer and have only bumped it up to 6 miles once a week in the last month. He stays busy enough that I don't need to go ride with him more than once a week, if I did he would have way too much activity in his daily schedule. Four days a week he goes to my parents place and plays with their English Shepard and Aussie all day, one day a week he goes to a doggy daycare group all day, and then the weekends we go adventure.
Commands I use when riding and some are used in normal life:
Come Around: clockwise turn
Other Way: CCW turn
This Way: you went the wrong way and need to pay attention (yes there is some confusion with "other way" but this is just how he ended up learning this command)
Too Far/Far Enough: stop and wait + implied that a recall is coming. We also use this as a boundary command at home to keep him on our property.
Lead
Follow: Still working on this one.
Slow: mostly used when hiking down hill, but he slows to a walking pace and stops pulling on the lead if he is on the lead.
Keep On: keep on running past things and go straight
Leave it: ignore people, dogs, and things.
Take a Break.
Spot: lay/sit/stand between my legs or at my feet. Super useful for getting him back in reach so I can grab his harness when people go by just in case.