I have a black lab who is an excellent trail dog. They are very trainable dogs so work well in the correct conditions.
If you haven’t already done so, have your dog hip-scored at the vets to ensure that you are not likely to cause issues. My vet recommended that there should be no more than 5-10mins of exercise per day per month of age until 18 months. Our vet knows our dog is a trail dog and is fully supportive of it as he is in great shape.
As others have said recall is essential. Recall is pretty easy to train with labs as they will do anything for food. 30mins in the back garden one evening was all it took with mine at around 16weeks old. He was giving a paw at 12weeks.
I have no problems at trail centres although I would not take him in a weekend as its too busy. Night rides he wears a reflective jacket for safety and visibility.
Our dog loves water so,plenty of stops for drinks and rolly-polly in streams etc.
At first we spent a lot of time talking to him the whole way round just to keep him close and calm. He quickly got the hang of it and it’s second nature now. He thinks he was made for chasing our bikes although interestingly he won’t chase anyone else’s bike.