A nice 7 speed screwon or change to an average cassette?

For the commute bike the rear rim is getting a bit thin,
here's the choice;

- Retain a reasonably good 7 speed Athena drivetrain with screwon
sprocket, lace up a new rim on a very nice suntor sprint hub (from the
"junk" box),

or

- if I can find a 7 speed cassette, change to a cassette mechanism
on a medium range off-the-peg wheel (haven't found one yet)

or

- upgrade the 7 speed athena ergos to 8 speed (is this possible?)
and change to an 8 speed cassette on a medium range off-the-peg
wheel.

thanks
Matthew

 

Buy a wheel, 8 speeed cassette and EF29 shifters, the lot is about 100-150 depending on the quality of the wheel and choice of road or MTB cassette.

I did this with my Merida last year, it beame a great little bike.

Now have a spare 7 speed spin on, sold the wheels...

 

I was kinda hoping to stick with campy, foolishly thinking
that I may be able to change from 7sp Athena to 8sp
Athena with only a rachet cog in the ergo levers?
(anyone done this?)
Do I need to change the rear dr as well?

regards,
Matthew