Here are some tips on how to motivate someone to buy a mountain bike, and then to prepare to take an overnight bicycle tour camping along the way:

1. Find out what they are interested in. What kind of activities do they enjoy? What are their hobbies? Once you know what they are interested in, you can start to tie in mountain biking with those interests. For example, if they are interested in nature, you can talk about how mountain biking can be a great way to explore the outdoors. If they are interested in fitness, you can talk about how mountain biking can be a great way to get exercise.

2. Make it fun. Don't just tell them about all the benefits of mountain biking. Show them! Take them to a local bike shop and let them try out different bikes. Take them for a short ride on a trail. The more fun they have, the more likely they are to want to do it again.

3. Set realistic goals. Don't try to convince them to go on an overnight camping trip right away. Start with something small, like a short ride on a local trail. Once they have mastered that, you can start to gradually increase the distance and difficulty of their rides.

4. Be patient. It may take some time for them to warm up to the idea of mountain biking. Don't get discouraged if they don't want to do it right away. Just keep offering them opportunities to try it out and eventually they will come around.

Here are some additional tips to help them prepare for their overnight bicycle tour:

5. Make sure they have the right gear. This includes a good mountain bike, a helmet, a backpack, and other essential gear.

6. Help them train for the trip. This means going on regular rides and gradually increasing the distance and difficulty of their rides.

7. Talk to them about the importance of safety. This includes things like staying hydrated, being aware of their surroundings, and knowing how to fix a flat tire.