Upgrading 20 year old road bike's groupset I own an Scott AFD 709 from the late 90s to early 2000s with an Ultegra 6500 group set. Would it be possible to upgrade to the newest Tiagra 4700 groupset (https://www.vanillabikes.com/products/shimano-tiagra-4700-groupset)?

Which kind of problems would I have to face?


The cassette should fit, as it is a 10 speed one, which is compatible
to the 9 speed free wheel hub.
The bottom bracket and chainset should fit as well.
Does the rear derailleur fit? Probably yes, why shouldn't it?
Are the brakes compatible? They look a bit longer...
My biggest fear is the front derailleur. The bike currently is currently brazed on. It is at the lowest position. Could it maybe fit nevertheless?


Here are some photos of the bike:
I agree with the folks who suggest that you stick to the 9-spd Ultegra, especially since it already has index shifting and "brifters" (you can brake and shift at the handlebar without moving your hands from the hoods). If it's looks you're going for, you can always clean up the parts, and if the anodizing is a bit worse for wear, you can always use some oxalis acid to take it off and polish the pieces to a mirror finish. Tiagra is second lowest on the Shimano line (above Sora) and Ultegra is still their second highest. The quality of the craftsmanship still doesn't compare, even in 20 yrs. There isn't much of a difference between 9 and 11 on the back, except that 11-sp components last shorter time because they are thinner and more fragile. If you do want easier ratios, why not swap out the front rings for compact ones? Just my 2 cents.