Wenn ich durch die Baustelle gefahren bin, wird mein Fahrrad kaputt sein.
Wenn ich durch die Baustelle fahre, wird mein Fahrrad anschließend kaputt sein.
The part before the comma is a subordinary clause, so the verb comes last.
In the main clause the verb is second, but the initial subordinary clause is the first part of the sentence, so the verb must immediately follow. An additional "dann" after the comma is possible but unnecessary and should be avoided (but that's a matter of style).
3rd person singular of werden is wird.
The tenses are a bit tricky:
Because the sentence tells what will have happened after you ran through the building site, either the perfect should be used for the subordinary clause or you should make clear that you are talking about what happens afterwards by adding anschließend. Danach is also possible.
I'm assuming that the bike is ridden through the building site, so fahren must be used instead of laufen. If it's actually a walk then laufen is correct.