Originally Posted by aliasfox

Yes, you can replace the 105 if needed. I think 9-speed Sora, which is currently on the market, would be the drop-in replacement. However, if you're thinking that the 105 is high-mileage, and too old to last very long, it might be better just to buy a new Sora bike instead (wait for a Decathlon to come in stock). Parts and labor add up quick, and like I mentioned, if that's 9-speed 105, it's coming on close to 20 years, and might have 20k miles/30k km on the derailleurs, cassette, and chainrings.

Will you have a chance to test-ride it? If you do, I would go for it, and make sure the bike shifts well and doesn't have chain-skip issues. However, given that you're quoting distances in miles and the shop is in Belgium, I would imagine that's difficult.

So... from what I can surmise:
- You're looking at a ~20 yr old Ridley of unknown provenance
- The bike is in Belgium, and you're in the US
- The bike costs $350, shipping is likely another $150, not to mention waiting for it to clear customs

At this point, I'd probably pass and look on local craigslist. It may be a perfectly fine bike, but it's probably not unique, and may require work. And do you want to risk your money if that's the case?