[imwjl]

I do get some sentimental value with some bikes but confess we've sold or traded several in our fleet for the performance, comfort and control modern ones have. The fleet context is we've had several years with mom, dad and kids same or about same height and sharing bikes.

For fat bikes we've had the earlier 4" (most are labeled 3.8) and newer where I moved to 4.6" very knobbed and studded tires. Now the fattie is dedicated to winter riding only. It's more often when I appreciate the 4.6 inch studded Gnarwhal tires than miss faster 3.8 in tires. We've for sure been 1x with fat bikes for a while now.

My guess is if you have 2x and 4" tires, you have a hub that can have a wide-range 10 speed Shimano type cassette and a 30t 1x front to cover about anything. You could also do a SRAM NX conversion. NX uses the Shimano style splines and doesn't require XD type.

Keep this in mind on "old", upgrades, trades or the investment. A few new bike purchases and parts changes have made an incredible difference. The newer fat bike and modern trail bike have completely changed what this old guy can still do. Those and my few months ago gravel bike purchase also make a huge difference in how long I can ride and not suffering afterwards for doing it.

For your mentioning the $ few hundred, when a bike needs it's 3rd chain I usually need new chain ring(s) and cassette. When edges of fattie and MTB tires look a bit shredded you lose they lose more performance than you might think and can be dangerous if you really know how to turn a bike.

Like guitars, the pleasure and well being from it all is well worth the price tags.