I finally bought a bike! Its a Trek Marlin 4, 2021. Thanks for everyone from this community who suggested it and especially u/badger906 for explaining me a lot of basics : r/mountainbiking
Trek Marlin 8 Gen 2 - Wheel & Sprocket | One of America's Best Bike Shops
Trek Marlin Mountain Bikes - 2021 - Roe Valley Cycles
It's been around two weeks since I bought Trek Marlin 4, 2021 and I freakin' love it. I'd like to change transmission (from 3-7 to 1-12 or 14), so what components will