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Hi everyone, I have a 2019 Trek FX 7.3 with a large size frame. For fun and also to learn more about bike mechanics I want to convert it to a gates belt drive and a nexus or alfine hub. Does anyone know if this would be possible and if so how I should start? Thanks

Hi Keith,

Belt-drive bikes have a frame that allows for the right/rear triangle to be opened to install the belt.
A frame shop could modify your frame.
Or you can buy a belt that is installed in your frame, then the ends are joined.

Thanks and good health, Weogo

No you cannot adapt that frame for a Gates Belt Drive, however there are a ton of great bikes with Gates already on it or frames that are ready to accept a belt drive that you can build up.

I wouldn't put a bunch of money towards the bike either ride it as is or save up your money towards the bike that has the features you want. Gates Belt Drive systems are awesome and well worth it but I would get something already built up personally it would be easiest especially in figuring out gear ratios and belt lengths since it is already set up and calculated.

As others have said, it isn't possible. A belt drive frame has the rear seat stay bolted to the drop out in some fashion, I've seen different varieties, so that the belt can be slipped into the frame. This is because the current chain runs from inside the frame at the hub to outside the frame at the crank both top and bottom and without the break in the frame you have to pin the chain, the belt offers no such option.
Personally, I've run nexus hubs in the past, used one for a commuter. But your 7.3fx wouldn't benefit from the conversion and in my experience that is a nice fitness/commuter bike that doesn't lack for much. Sure, there's better, but it is just a generally nice bike as is. Using an alfine or nexus you want to pair the gearing of the crank to match the ratios of the hub and which has a proper chainline from crank to cog. So even skipping the belt you're probably looking at a crankset, bb, rear hub,/wheel, new shifter, and new grips to make it all work. A lot of work for a bike that's already nice and functioning. Now buying a frameset and building a bike because you want a r+1, not always worth the cost but still a worthwhile endeavor just to see what you can accomplish.