A vintage Trek will need a 28.6mm front derailleur clamp. The Sora FD with the 31.8 clamp will include a shim to use it with your 28.6 seat tube. The bottom bracket on your vintage Trek will be BSA/English threaded so the BB-RS500 bottom bracket will fit.

Depending on the particular vintage Trek you have the Sora brakes may not reach the rim. If you have this problem, you can get either Tektro R539 or R559 brakes that will reach and will work with the Sora levers.

You're getting new wheels, right? Even though 10-speed wheels will work with the Sora cassette, you may want to consider 11-speed compatible wheels if you're buying new.

The Trek very likely has the old "diver's helmet" style cable stop for the rear derailleur and so won't work with current ferrules. You need this: https://www.universalcycles.com/shop...&category=1613

Assuming your Trek doesn't have a plastic bottom bracket guide screwed on to the bottom bracket (and I don't think it will), you should consider stopping by your LBS and picking up a couple of small pieces of PVC cable liner (like this: https://www.universalcycles.com/shop...&category=4385). That will reduce friction at the bottom bracket cable guides that could cause problems with indexed shifting.

Lastly, while it isn't absolutely necessary, it is very helpful to have barrel adjusters somewhere in your shift cable routing. If your Trek has downtube shifters (or at least the bosses to mount them), you can get bolt-on cable stops with built-in barrel adjusters (like this: https://www.universalcycles.com/shop...&category=1613) that make for a clean and convenient solution. If you don't have downtube shifter bosses, you can get clamp-on bosses on eBay. It's often cheaper to buy clamp-on shifters and just remove the shifters. If you live near a co-op they can probably sell you a pair of these for cheap.

Sorry if I've provided a lot of answers to questions you didn't ask and already knew the answers to. I've been putting together a guide to modernizing old bikes, and answering your original question provided an opportunity to review my organization. Was it helpful?


(BTW, I have no affiliation with Universal Cycles and don't mean to shill for them. That's just where I shop and so it's the easiest place for me to find references to the pieces I was talking about.)