Something I'd like to point out that hasn't been noted yet is the other two notable speeds you can hit at between the two gears. -and yes, there are two extra notable speeds between the two gears, but it's a little more complicated than just swapping between four possible speeds.
I dunno how important this is, probably very minorly, if not at all, but it's interesting to note, and very well could come up later in the meta.
Just to start off, I want to point out that a low gear dash does 4%, where a high gear one does 7%. Already I'm betting some of you can guess what the two other notable speeds are, and you'd be right, they're the two speeds where dash does 5% and 6%, respectively.
Now the difference between 4% and 7% dashes is already miniscule - I can't think of any combos or set-ups where a 4% dash can't take the place of a 7% dash at later %s and vice versa - but the extra speeds might at very least be useful for milking that extra 1-2% from your dash combos and still nailing it where a 7% dash might not hit.
I personally couldn't find any specific instances where a 5/6% dash could hit where a 7% couldn't (In order to milk extra damage, or kill slightly earlier.), but I'll put that down to me being bad at labbing anyway.
The other thing I should note is that even though there are 4 speeds, there are still only 2 gears (To my knowledge.). Let me repeat that, because it's important to how this tech works - there are only 2 known gears between 4 damage outputs. -and this causes a problem, because it makes such a minor tech a very difficult thing to pull off.
You basically have a very precise window between the two gears to hit one of two of these extra speeds, so accuracy is kinda crucial. That being said... You can tweak your speed to stay between the two gears... Yep, this is getting needlessly complicated...
I just want to point out that from this point forth, I don't really want to be using the "gear" term, since it's a bit of a misnomer, but I will be referring to 4% dash and 7% dash as Lowest and Top speed (LS and TS for speed's sake.), respectively.
From LS, the only real option seems to be to accelerate right to TS, and while that feels like the case in 9 out of 10 cases, it's just absolutely not true. You can actually stop accelerating at a 5% or 6% dash and carry on speeding right on through your opponent. I don't know the amount of frames it takes to accelerate from LS to TS, but it's an incredibly small gap, like... -a few frames small, so stopping acceleration at 5% or 6% is absoloutely needlessly complicated.
The other thing to note is that deceleration is very much possible! -you just can't control it... It happens naturally (and painfully slowly), and you can check it out yourself easily in practice mode (Especially with the time slowed down.). Enter FD or an Omega, spawn 2/3 CPUs and then accelerate to TS, and then let go of the input. You'll actually do less damage as time goes on. I was even able to hit the first CPU for 6%, the next by 5%, and then the third, I accelerated back up to TS for 7%.
I don't know if any of this information is different in the Wii U version (I'm assuming not.) but it's worth looking into anyway.
The way I understand the kart's speed, and ergo it's damage, is that you're effectively swapping between a binary input that moves your speed along a scale. It's not a definitive 0 or 1 move, it's not limited to LS and TS, but the inputs you can perform are basically limited to trying to hit these speeds.
It's not unknown for moves to do fractions of %s, and this one is no exception. -and again, you can test this yourself by simply equipping yourself with extra damage in customs. With a +200 attack stat, your LS is 9%, whereas your TS is 14%, giving you an effective 4 extra notable speeds to work with, and you can scale your speed to all of them, the windows for such are just more precise since the scale is still limited by your LS and TS, and you're now splitting 6 possible damage outputs between it, instead of the usual 4.
So, in a sense, saying the move has a "Low Gear" and a "High Gear" isn't too much of a stretch, but it's not strictly true. It should just be noted that as a player, you're controlling the move's acceleration between two speeds that do different damage outputs, and basically nothing else, so...
Well, that's all my input on the subject. I'm sure it's all very dull and such, but the way I see it is that any and all information is welcome and potentially valuable - plus it really brings some insight to the inner workings of the move, which I'm sure someone will find interesting.
TL;DR: There are unsurprisingly more than two speeds this move can hit at and they do incremental damage similar to which is seen in charge moves such as Samus' notorious Charge Shot, but there are still only two states of acceleration you can be in and you control those rather than the move's actual speed. -it's also incredibly hard to control hitting between the two extremes since the lowest and highest speeds are literally frames of acceleration apart.
