Die Gangschaltung ist am Lenker.

German very often combines nouns into a single compound noun.

• Gang = gear
• Schaltung = shifting system / gear mechanism

So Gangschaltung means gear shift or gear shifter/gearing system, depending on context.

This is completely normal in German. English often writes similar ideas as two words, but German usually joins them.

Gangschaltung is feminine, so it takes die in the nominative singular.

A useful rule for compound nouns is:

• the last part decides the gender

Here, the last part is Schaltung, and die Schaltung is feminine.
So the whole compound is die Gangschaltung.

am is a contraction of an dem.

So:

• am Lenker = an dem Lenker

In this sentence, an means something like:

• on
• attached to
• at

So am Lenker means on the handlebar or at the handlebar, depending on how the English translation is phrased.

Because this sentence describes location, not movement.

German prepositions such as an can take either:

• dative for location: where?
• accusative for movement toward something: where to?

Here:

• Die Gangschaltung ist am Lenker.
• It tells us where the gear shifter is.
• So German uses the dative.

That is why you get an dem Lenker → am Lenker.

Compare:

• Die Gangschaltung ist am Lenker. = The gear shifter is on the handlebar.
• Ich montiere die Gangschaltung an den Lenker. = I attach the gear shifter to the handlebar.

It is in the dative case.

Reason:

• the preposition an is being used for a fixed location
• fixed location takes the dative

You can see that in the article:

• der Lenker = nominative
• dem Lenker = dative
• am Lenker = an dem Lenker

Lenker is singular here.

In a bicycle context, der Lenker usually means:

• handlebar
• sometimes the handlebars in natural English translation

This is one of those cases where German and English do not line up perfectly word-for-word. German uses a singular noun, while English often prefers the plural handlebars.

So am Lenker may be translated naturally as either:

• on the handlebar
• on the handlebars

depending on context.

Because German main clauses usually follow the verb-second rule.

In a normal statement:

• first position: one element
• second position: the conjugated verb

Here:

• Die Gangschaltung = first element
• ist = second position
• am Lenker = the rest

So the word order is completely normal for a German statement.

Usually am Lenker is the more natural choice.

Why?

• an often suggests something is attached to or located on the side/surface of something
• auf more literally suggests on top of

A gear shifter is thought of as mounted/attached to the handlebar, so am Lenker sounds more idiomatic.

So while auf dem Lenker might be understandable in some situations, am Lenker is the better standard phrasing here.

Yes. In German, all nouns are capitalized.

That is why you see:

• Gangschaltung
• Lenker

But articles, verbs, and prepositions are not capitalized here:

• Die is capitalized only because it starts the sentence
• ist
• am

So capitalization helps you spot nouns very quickly in German.

Yes. Some alternatives are possible, for example:

• Die Gangschaltung befindet sich am Lenker.
• Die Schaltung ist am Lenker.

These mean roughly the same thing.

Notes:

• befindet sich is a bit more formal or descriptive than ist
• Schaltung is shorter and may be used when the context already makes clear that you mean a gear shifter

But Die Gangschaltung ist am Lenker. is a perfectly normal, clear sentence.