Кермо настільки низьке, що велосипедисту важко їхати.

Yes. Кермо can mean steering wheel in general, but in the context of a bicycle it commonly means the handlebar.

A useful thing to remember is that Ukrainian often uses the singular where English prefers a plural:

• кермо = handlebar / handlebars
• English usually says the handlebars are low
• Ukrainian says кермо низьке = literally the handlebar is low

So even though English speakers think of bicycles as having handlebars, Ukrainian treats it as a singular noun.

Низьке is the adjective низький (low) agreeing with кермо.

Agreement in Ukrainian means the adjective matches the noun in:

• gender
• number
• case

Here:

• кермо is neuter
• singular
• nominative

So the adjective must also be neuter singular nominative:

• masculine: низький
• feminine: низька
• neuter: низьке
• plural: низькі

That is why we get кермо ... низьке.

In the present tense, Ukrainian usually omits the verb to be.

So:

• Кермо низьке = The handlebar is low
• literally: Handlebar low

This is completely normal Ukrainian grammar.
If you wanted past or future, then forms of бути would appear:

• Кермо було низьке = The handlebar was low
• Кермо буде низьке = The handlebar will be low

But in the present tense, the linking verb is normally just left out.

This is a very common pattern meaning so ... that.

Structure:

• настільки = so / to such a degree
• що = that

So:

• настільки низьке, що... = so low that...

The whole sentence has the pattern:

• X is so [adjective] that Y happens

Examples:

• Він настільки втомлений, що не може працювати.
  He is so tired that he cannot work.
• Було настільки холодно, що ми не вийшли.
  It was so cold that we didn’t go out.

Because Ukrainian often uses the dative for the person who experiences a feeling, difficulty, possibility, necessity, and similar states.

Here:

• велосипедисту = to the cyclist / for the cyclist
• важко = hard / difficult

So велосипедисту важко literally means:

• to the cyclist, it is difficult
• or more naturally in English: it is hard for the cyclist

This dative pattern is very common:

• Мені важко. = It’s hard for me.
• Йому холодно. = He is cold.
  literally: To him, it is cold.
• Нам треба йти. = We need to go.
  literally: To us, it is necessary to go.

Важко here is not an adjective agreeing with a noun. It is a predicative adverb / state word meaning hard, difficult.

Compare:

• важкий велосипед = a heavy bicycle
  Here важкий is an adjective describing a noun.
• мені важко їхати = it is hard for me to ride
  Here важко expresses a state or difficulty.

So in this sentence, важко means it is difficult, not heavy.

Їхати means to go / travel by vehicle or to ride in a vehicle sense. Since a bicycle is a vehicle, Ukrainian naturally uses їхати.

So:

• їхати на велосипеді = to ride a bicycle
• in this sentence, the bicycle idea is already clear from велосипедист, so simply їхати works well

This is different from:

• йти = to go on foot
• бігти = to run
• плисти = to swim / sail

Because їхати and їздити are different kinds of motion verbs.

A simple way to think about it:

• їхати = going by vehicle in one specific instance / one direction
• їздити = going by vehicle habitually, repeatedly, or in various directions

In this sentence, we mean the actual action of riding at that moment or in that situation, so їхати is the natural choice:

• велосипедисту важко їхати = it is hard for the cyclist to ride

If you said велосипедисту важко їздити, it would sound more like:

• it is hard for the cyclist to ride bikes in general / to ride repeatedly

So їхати fits better here.

Що introduces the subordinate clause after настільки.

So the sentence is divided like this:

• Кермо настільки низьке = main clause
• що велосипедисту важко їхати = subordinate clause

Together:

• The handlebar is so low that it is hard for the cyclist to ride.

In this kind of sentence, що is simply the conjunction that.

Not completely. Ukrainian word order is fairly flexible, but the original order is natural and neutral.

Neutral version:

• Кермо настільки низьке, що велосипедисту важко їхати.

You might also see:

• Велосипедисту важко їхати, бо кермо настільки низьке.
  = It is hard for the cyclist to ride because the handlebar is so low.

Within the second clause, changing the order can shift emphasis:

• ...що велосипедисту важко їхати = neutral
• ...що важко їхати велосипедисту = more marked, emphasizing the cyclist

So the original sentence is a good standard model.

Because що introduces a subordinate clause, and Ukrainian normally separates that clause with a comma.

So:

• Кермо настільки низьке, що велосипедисту важко їхати.

This is standard punctuation.

A good rule of thumb: when що means that and starts a dependent clause, a comma is usually needed before it.

You could sometimes say для велосипедиста, but here велосипедисту is much more natural.

Compare:

• велосипедисту важко їхати = it is hard for the cyclist to ride
  This is the normal Ukrainian structure.
• для велосипедиста важко їхати sounds less idiomatic here

The dative is the standard way to mark the experiencer with words like:

• важко = hard
• легко = easy
• холодно = cold
• треба = necessary
• можна = possible / allowed

So it is best to learn this pattern as a chunk:

• комусь важко щось робити = it is hard for someone to do something

It can be understood either way, depending on context.

• велосипедисту literally means to the cyclist
• Without more context, it can mean:
  • a specific cyclist already known from the situation, or
  • a generic cyclist, meaning a cyclist / anyone riding it

So the sentence may mean:

• The handlebar is so low that the cyclist has difficulty riding or
• The handlebar is so low that it is hard for a cyclist to ride

Ukrainian often leaves that kind of definiteness to context rather than using articles like the or a.