How To Find The Right Size Seat Post For A Bike

I bought this bike at a thrift store, but it was missing the seatpost and seat. I show the steps I go through to determine what diameter of seat post is needed to fit the frame.
The bike is a Trek 3700 mountain bike.
Seatpost Size - From Wrong To Right:
• Seatpost Size - From W...
▶ SUBSCRIBE & HIT THE 🔔 bit.ly/SubRJTheBikeGuy
👍 And please give my video a thumbs up 👍
▶FACEBOOK.com/RJTheBikeGuy
/ rjthebikeguy
▶TOOLS
www.rjthebikeguy.com/tools
▶SHIRTS
bit.ly/RJBikeGuyShirts
▶WEBPAGE
www.RJTheBikeGuy.com