How to Build a 1x Drivetrain for $0 (The Grinder Method)

If you’re wondering how to convert a 3x7 mountain bike to a 1x drivetrain without spending a lot of money, this video walks through the entire process step by step. In this rebuild of a 2012 Trek 820, I remove the extra chainrings from a riveted 3x crankset using an angle grinder and convert the bike to a simple 1x7 drivetrain. No new crankset. No narrow-wide chainring. Just a practical budget method that works on cheap mountain bikes. This conversion eliminates the front derailleur, simplifies the handlebars, reduces cable clutter, and makes the bike easier to ride and maintain — especially for younger riders or casual use. In this video you’ll see: • How to remove two chainrings from a riveted crank • How to safely grind a 3x crank into a 1x • Rebuilding with a Shimano 14–34T Megarange freewheel • Installing and tuning a Shimano Tourney rear derailleur • Cable routing and quick derailleur adjustment tips • The final clean 1x setup on a budget MTB The final gearing uses a 36 tooth front ring paired with a 14–34 tooth 7-speed freewheel, which provides solid hill climbing ability and good cruising speed for everyday riding. This method works best on budget stamped steel cranksets where upgrading doesn’t make financial sense. If you're building a trail bike or riding aggressive terrain, a narrow-wide chainring would improve chain retention. This video is part of a full Trek 820 rebuild series where I repaint the frame, replace wheels, upgrade handlebars, and simplify the controls. If you're rebuilding an old mountain bike, restoring a cheap MTB, or considering a 3x to 1x conversion, this will give you a realistic look at what works and what to expect. #1xConversion, #3xTo1x, #MountainBikeRebuild, #BudgetMTB, #MTBUpgrade, #BikeMechanic, #Trek820, #DrivetrainUpgrade, #BikeRestoration, #CheapBikeBuild, #DIYMountainBike, #ShimanoTourney, #BikeRepair, #MTBHowTo, #7Speed ************************************************************************* I only recommend items I actually OWN and use. The links above may provide a small advertising commission at no added cost to you.