Questions & Answers about Jeg lover ikke at glemme at spænde hjelmen.
Since ikke is between the main verb and the infinitive, does it mean 'I don't promise' or 'not to forget'?
In written Danish, it can technically mean both! In a main clause, the adverb ikke goes right after the finite verb (lover). But when negating an infinitive phrase, ikke is placed right before at. Because of this, both structures put ikke in the exact same spot here. You have to rely on context, which clearly points to 'I promise not to forget'. In spoken Danish, the rhythm and stress of the sentence would make the meaning obvious.
If I wanted to use a different adverb, like aldrig (never), where would it go?
It follows the exact same rule as ikke. If you want to say 'I promise never to forget', you place the adverb right before the infinitive marker: Jeg lover aldrig at glemme at spænde hjelmen.
Why do we need the word at twice in this sentence?
You are chaining verbs together, and Danish requires the infinitive marker at (to) before each infinitive verb in the chain. After the main verb lover, you have the first infinitive at glemme (to forget). The action you are forgetting is also in the infinitive: at spænde (to fasten). It works exactly like the English translation: 'to forget to fasten'.
Is at spænde hjelmen literally about a helmet, or is it an idiom?
It can be completely literal, like fastening a bicycle or construction helmet. However, at spænde hjelmen is also a very common Danish slang expression that means 'to pull yourself together', 'to pay attention', or 'to use your brain'. Depending on the context, the speaker might actually be promising to stay sharp and focused!