upgrade my road bike, compatible parts to upgrade in phases? I received a used road bike that functions, but not well.  I completed a triathlon and lots of practice rides, but wanting to upgrade the components.

The crankset is ultegra 6500/170m.  The shifters and FD are ultegra (prob 6500 too?) and the RD is tiagra. Not positive about the cassette (is there models markings there somewhere?)

My goal is to slowly upgrade (based on budget) to either 105 5800 or ultegra 6800.
1) can I upgrade the shifters, FD, and RD and keep my existing crankset and cassette for upgrade later?
2) is there an upgrade path that lets me upgrade a few components at a time to eventually get me to a modern groupset?
3) best place to get affordable parts?

The frame is in great shape.  Aluminum with carbon fork.  Bike weighs in at 19 lbs, fully loaded.  Shimano rims, etc.  Would prefer to upgrade this bike.

Thank you
I received a used road bike that functions, but not well.


Just to point out: If shifting works bad it’s usually a problem with friction in the cables, bad adjustment, bent hanger or worn chain/cassette. Even a relatively cheap Tiagra group works flawlessly when properly installed and adjusted.

I don’t see many options for a partial upgrade because the cassette-spacing has gotten narrower from 9-speed to 10-speed to 11-speed. So you can’t use 11 or 10-speed shifters with 9-speed cassettes or vice-versa.

Anyways, you’d probably have to install new cables and re-adjust for every step so it doesn’t make much sense.