You can do it!!
Your cost should be < €300 if you DIY ... half that amount if you are a wise shopper ...
- 10-speed (or, 11-speed!) CAMPAGNOLO shifters you can buy a used pair in VERY GOOD condition off of eBay for < €100
- the Campagnolo shifters will give you the most future configuration flexibility that is, a different/contemporary wheelset
[*]you can ALWAYS move these to another bike in the future, so think of the cost on a 5-to-10 year basis
[*]Shimano rear derailleur (see matrix, below)
[LIST] try your bike's current rear derailleur, first
[*]ANY front derailleur
[*]7-speed SunRace Freewheel (about €15)...
[LIST] the Cogs are
Ramped
[*]chain? (I recommend a Shimano chain -- 8-speed or 9-speed )
[LIST] a 9-speed Shimano chain can be used with a broad range of configurations ... you WILL need a "contemporary" chain tool which is spec'd for 9-speed or narrower chains
[*]an inexpensive 9-speed Shimano chain will work as well as their expensive variants
[CENTER] [/CENTER]
[CENTER][IMG]cyclingforums.com700Open ↗[/IMG][/CENTER]
And, you'll be good to go ...
There ARE some bicycle specific tools ...
The skill level, in general, is comparable to removing-and-replacing the cap from an old-style (i.e., glass) ketchup bottle -- some dexterity is required, but not much ...
- 99% of the information you need is available on www.parktool.com + YouTube.
The biggest hassle may be acquiring the downtube stops PLUS cutting/trimming the cables & housing -- the "stops" used to be supplied with the shifters ... if your frame does not have braze-on bosses, then you will need the cable stops commonly used for stem/bar-end shifters ... if your frame has cable guides on the downtube, already, then so much the better.
The most time will probably be spent wrapping the handlebar tape!
IMO, the people who should NOT work on their own bikes are surgeons/dentists/dental-hygenists/hand-models OR people with arthritis because if a tool should slip (unlikely, but ...) and they are out-of-commission for a day-or-longer, then it is potentially lost income.
Don't be in a hurry ... consult YouTube or www.parktool.com when you need to ... after you have the tools & components it's a "weekend" project.
Now, is it worth it?
Many will say "no."
I say that presuming the fork is not damaged, then for 1/4th the cost of a comparable, new bike from an LBS you can cobble together a better bike with an existing frameset + parts + DIY time-and-effort.
You can do it!!!