I need to get from Israel to Frankfurt next month. As the flight costs are very expensive, I thought of taking a flight to a nearer location - some European city to the east of Frankfurt, and then take a fast train to Frankfurt.
Question: what major European airports have a fast train service to Frankfurt?
You are right that flights to Frankfurt appear to be more expensive than some other cities.
My recommendation is to check out capital cities nearer to Israel in eastern Europe. You can do this with Expedia to get flights and a combination of Google Maps (for train running times) and The Man in Seat 61 for train prices.
For example, a quick examination shows that by flying to Prague you can save more than 300 Euros on airfare, and get a train to Frankfurt for 60 Euros. Of course you are adding quite a few hours to your travel time.
Trains get slower and slower the further East you go and Germany mostly upgraded north-south lines. Going from Prague to Frankfurt takes 7 hours vs. under 4h from Paris. Even trains to Berlin or Dresden are slower than trains to Cologne, Brussels or Paris.
So if you want a convenient and fast connection, your only options outside Germany are Brussels, Amsterdam, and Paris (all further West). Vienna or Warsaw are doable and you might also consider Munich or Cologne (North/South rather than East) if that's somehow cheaper but that's about it.
Anything else (Rome, Budapest…) is the kind of things I would actually do because I love overland travel but it's not fast or convenient by any stretch of the imagination.
Paris is 4h from Frankfurt by TGV/ICE, Brussels, Berlin, Zurich are 3-4h using ICE, Munich is 3h away by ICE
Connecting flights can be cheaper sometimes. I looked up isreal to Athens, and then onward to frankfurt and it was a little bit cheaper then direct flight to frankfurt. You can use the multi stop option on google flights instead of round trip or one way to find these routes on a single ticket.
