From the answer in another question of this board, 東京に行くには何で行きますか translates as "About you going to Tokyo, how are you going?" . Why is the second "ni" needed in this sentence?
The second に is for marking a purpose. The English equivalent is "(in order) to" as in "Click to see it." The more literal translation would be "To go to Tokyo, by what do you go?" This に is frequently used with 行く (
go to + (verb)).
Japanese Particle Ni — Indicating Purpose
- 本場の寿司を食べに日本に行った。 I went to Japan to eat real sushi.
- 見に来て！ Come and see it!