Learn Hardcore Chinese: wǒmen shì qí zìxíngchē qù de, bú shì zuò dìtiě qù de.

It’s a focus/cleft construction that highlights specific details of a completed or known action. Here it emphasizes the manner/means: It was by bike that we went (and not by subway). It presupposes that the trip happened and focuses on how it happened, not on whether it happened.

Why are there two instances of 是?

They mark two parallel cleft clauses for contrast: 我们是骑自行车去的 (affirming the actual means) and 不是坐地铁去的 (denying the alternative). The second one uses 不是 to negate the clefted element.

What is the final 的 doing? Is it the possessive 的?

This 的 is the sentence-final particle of the 是…的 construction, not the possessive 的. It “closes” the clefted focus and signals that we’re specifying details about an already-occurred event. Without this 的, the cleft feels incomplete.

Why use 不 (bú) and not 没 (méi) here?

Because we’re not denying that the trip happened; we’re denying the manner. 不是坐地铁去的 says “it’s not by subway that we went.” If you want to deny the action itself, you use 没, e.g., 我们没去 “we didn’t go,” or 我们没坐地铁去，是骑自行车去的.

Can I say this without the 是…的 structure?

Yes: 我们骑自行车去，不坐地铁 is fine and natural. It’s less emphatic and not explicitly framed as referring to a specific completed event; it reads more like a plain statement or plan depending on context.

Can I drop 是 or 的?

Dropping 是 is common in speech: 我们骑自行车去的 (still a cleft).
Dropping 的 while keeping 是 is generally odd: 我们是骑自行车去 sounds unfinished.
If you drop the entire cleft, just say: 我们骑自行车去.

Why is 去 placed before 的? Could I say 我们是去骑自行车的?

我们是骑自行车去的 focuses on the means of going (we went by riding bikes).
我们是去骑自行车的 focuses on purpose (we went there to ride bikes).
Swapping the order flips the meaning from “means” to “purpose.”

Do I need 去 at all? What about 我们是骑自行车的?

Including 去 (or 来) makes it clearly about that trip. 我们是骑自行车的 without 去/来 is more likely to be understood as a general/habitual description (“we’re the type who ride bikes”) unless the context already makes the specific trip obvious.

Why use 骑 with 自行车 and 坐 with 地铁?

Chinese pairs specific verbs with transport types:

骑 for things you straddle: 骑自行车, 骑马, 骑摩托车.
坐 for vehicles you sit in/on: 坐地铁, 坐火车, 坐飞机, 坐公交, 坐出租车.
Others: 开车 (drive a car), 打车/坐出租车 (take a taxi), 走路 (walk).

Is “我们是坐自行车去的 / 我们是骑地铁去的” acceptable?

No. Those mix the wrong verb with the wrong vehicle. Say 骑自行车 and 坐地铁.

How would I ask a yes/no question with this pattern?

Using 吗: 你们是骑自行车去的吗？
Using A-not-A: 你们是不是骑自行车去的？
The second often sounds more natural when you’re seeking confirmation.

How do 来 and 去 change the sentence?

Use 来 if the motion is toward the speaker’s location and 去 if it’s away.

If you’re now at the destination: 我们是骑自行车来的 (“We came here by bike”).
Talking about going somewhere else: 我们是骑自行车去的.

Can I strengthen the contrast?

Yes. Add 而不是 or 并不是:

我们是骑自行车去的，而不是坐地铁去的。
我们并不是坐地铁去的。 (stronger denial of an assumption)

What’s the tone of 不 in 不是?

Due to tone sandhi, 不 becomes second tone before a fourth-tone syllable, so 不是 is pronounced bú shì.

Can I use 了 together with 是…的?

Generally, don’t combine them to mark the same event detail.

我们骑自行车去了 highlights completion (with 了).
我们是骑自行车去的 highlights the manner of a (known) completed action.
Avoid forms like 我们是骑了自行车去的; they are usually unidiomatic.

Can I omit the second 去 or 的 in the negative half?

Yes. Ellipsis is common if the meaning is clear:

我们是骑自行车去的，不是坐地铁的。
我们是骑自行车去的，不是坐地铁。
Keeping full parallelism (…不是坐地铁去的) is also fine.

How would I emphasize a different detail (time/place) with 是…的?

Place the detail between 是 and 的:

Time: 我们是昨天去的。 (It was yesterday that we went.)
Place/source: 我们是从学校骑自行车去的。 (It was from school that we went by bike.)
Participant: 是我们骑自行车去的。 (It was we who went by bike.)

What’s the difference between 骑自行车去 and 去骑自行车?

骑自行车去 = go by bike (means).
去骑自行车 = go in order to ride a bike (purpose).
Compare: 我们是骑自行车去的 (means) vs 我们是去骑自行车的 (purpose).

Any regional word differences I should know?

Yes. Mainland commonly says 自行车 and 地铁. In Taiwan, you’ll often hear 腳踏車/脚踏车 for bicycle and 捷運/捷运 (MRT) instead of 地铁. The structure remains the same: 我們是騎腳踏車去的，不是坐捷運去的。