For sale is a beautiful Trek Marlin 4. This is a good bike, but I want to upgrade to a better mountain bike. 29-inch wheels and an 18.5-inch aluminum frame This past winter, I had a tuneup. The fork on this bike is also different from the stock one. The one on it has less travel and would be ideal for a trail or gravel bike. There are a few paint chips, but nothing functional. Make an offer for $300.