Encaixo o pedal; testo o guiador e o selim.

Because the sentence is in the 1st person singular of the present tense:

• encaixo = I fit / I slot in / I attach
• testo = I test

This kind of sentence often appears in:

• a first-person narrative
• a step-by-step description of what someone is doing
• instructions written from the speaker’s point of view

The infinitives are:

• encaixar → encaixo
• testar → testo

So the ending -o here marks I in the present indicative.

Encaixar has the general idea of fitting something into place, slotting it in, or attaching it so it sits correctly.

In this sentence, encaixo o pedal suggests something like:

• I fit the pedal
• I attach the pedal
• I put the pedal into place

It does not usually mean just a vague put. It suggests that the pedal is being positioned so that it fits properly.

Portuguese often uses the definite article where English may or may not use the.

So:

• o pedal
• o guiador
• o selim

literally mean:

• the pedal
• the handlebar
• the saddle

In Portuguese, this sounds natural when referring to a specific item involved in the action, even if English might sometimes say just pedal, handlebar, or saddle in a technical or instructional style.

There is an article before both nouns:

• o guiador
• o selim

This is very normal in Portuguese. When two singular nouns are linked by e (and), Portuguese often repeats the article:

• o guiador e o selim

English can also do this:

• the handlebar and the saddle

Repeating the article makes it clear that these are two separate objects.

Yes — in European Portuguese, guiador is the normal word for a bicycle handlebar.

This is a useful variety difference:

• European Portuguese: guiador
• Brazilian Portuguese: often guidão

So if you are learning Portuguese from Portugal, guiador is the expected word.

Selim is the saddle of a bicycle, meaning the part you sit on.

In English, learners often think of seat, but saddle is usually the more precise cycling term. So:

• selim = saddle / bike seat

In everyday English, many people would simply say seat, but saddle is often the best match in cycling vocabulary.

The semicolon links two closely related actions:

• Encaixo o pedal
• testo o guiador e o selim

It shows a pause stronger than a comma, but not as final as a full stop.

So the sentence feels like a sequence of actions in a process:

1. I attach the pedal
2. I test the handlebar and the saddle

A full stop would also be possible in many contexts, but the semicolon gives a smooth, connected flow.

Yes, it is the present indicative, but Portuguese often uses the present tense to describe:

• actions happening right now
• habitual actions
• step-by-step procedures
• vivid narration

So even though it is a sequence of actions, the present tense is perfectly natural.

Here it can sound like:

• I attach the pedal; I test the handlebar and the saddle.

This is similar to English instructional or narrative present:

• I open the box, take out the parts, and test the brakes.

Sometimes, yes, but it depends on context.

Encaixar can mean:

• to fit
• to slot in
• to insert
• to attach into place

For a pedal, I insert the pedal sounds a bit unnatural in English unless you are focusing on the mechanical insertion. More natural translations are usually:

• I fit the pedal
• I attach the pedal
• I put the pedal in place

So insert is possible as a literal idea, but often not the best final translation.

A bicycle does have two pedals, but the sentence is referring to one pedal at this point in the process.

So o pedal means:

• the pedal
• one specific pedal being attached or checked right now

This is very common in instructional or descriptive language: the speaker focuses on one part at a time.

If it were plural, it would be:

• Encaixo os pedais = I attach the pedals

Yes:

• Eu encaixo o pedal; testo o guiador e o selim.

But it is normally omitted because Portuguese is a pro-drop language: the verb ending already tells you the subject.

• encaixo already means I fit
• testo already means I test

Adding eu is usually only done for emphasis, contrast, or clarity.

This sentence is in the I form, which sounds personal or narrative. In manuals or instructions, Portuguese often prefers other styles, such as:

• Encaixe o pedal; teste o guiador e o selim.
  Fit the pedal; test the handlebar and the saddle.
  (formal command)

• Encaixa o pedal; testa o guiador e o selim.
  (informal command)

• Encaixar o pedal; testar o guiador e o selim.
  (instructional infinitive style)

So the original sentence sounds more like what I do, not necessarily a direct command to someone else.

In European Portuguese, guiador is roughly pronounced like:

• gee-ah-DOR

A few helpful points:

• gui- here sounds like gee
• the stress is on the last syllable: -dor
• European Portuguese often reduces unstressed vowels, so it may sound more compressed than a learner expects

A careful learner pronunciation might be something like:

• guiador → gee-a-DOR

The exact sound will vary a bit by speaker and region, but the final stressed -dor is the key part to notice.