Wow - I have a very similar story. Purchased a Soloist Team (silver and red) frameset from my LBS after I blew up my Cannondale in a crit. That would have been the summer of 2008. Raced and rode the hell out of that Cervelo for the next three years. It initially donned a SRAM Rival group that I had gotten off of Ebay. Then I moved those parts over to my cyclorcross bike, and the frame sat unused for two or three years since I had no real use for it - my carbon fiber roadie was getting the love. I tried to sell it, but didn’t have any takers. I didn’t realize how lucky that was at the time. I eventually got a set of Microshift shifters and derailleurs and turned it into my trainer bike. I would take it out when my main ride was in the shop, but the shifters rattled so loudly, that I couldn’t really stand to ride it outside.
Over the Covid summer of 2020, I decided to revamp the bike. I got a wireless SRM to replace the old wired Campy square taper that I had been running. I got a one position carbon fiber seatpost, a 105 11 speed groupset, new cockpit, and saddle, plus some carbon clinchers from an acquaintance. Everything was from Ebay/Facebook Marketplace, with the exception of the cockpit, so it was really cheap. Then I took it out to ride…
One of the things that you think when you get a budget bike is that it is transitory, and once you get enough to afford a nice bike, you will get it and feel the difference. By the time the revamp was done, I had tens of thousands of miles on some pretty excellent bikes. I expected to feel some drop off on the aluminum Soloist. Well, that didn’t really happen. It is just a really solid frameset. Get some decent parts on there, and it is absolutely fantastic.