The snippet is from Bach's Tocatta & Fugue, I've also had trouble with some similar parts in other songs.




I wrote in an arrow and the 2,5 1,4 fingering for the top hand, which is what I use to play it (2,5 1,4 2,5 1,4 etc). I'm hoping some of the fine pianists here can shed some light on how I might come about tackling this part. It's 4 runs made up of several 2-note chords, the first run plays smoothly, second one feels slightly tougher, third one I can't tackle at all, and the fourth is also challenging for me. I'm assuming the runs are meant to be played legato. I can play them through slowly with some trouble, I absolutely can't play through all 4 at tempo.

Thanks!

Yes the third one is nasty because your pinky gets caught between two black keys. Unfortunately there does not seem to be any option but to keep using the 5-2 and 4-1. I don't see any place where the middle finger would be of any use (except for sticking it up in desperation ).
I think nothing but patient slow practicing will help here, lifting the fingers up demonstratively after playing a note. Maybe part of your problem is that you stay in the keys for too long ? It helps of course to have adequately-sized hands.
Good luck !

Two more thoughts :-

Yes I think these are supposed to be legato. But it's not always necessary (or even possible) to play all notes in a chord legato. In cases like this it's often sufficient when the leading (top) voice is legato.

You could think about having the LH help out a bit (assuming you are using some pedaling). This is often a good idea but in this case you have not so much spare time and I'm not sure though if that will do much good here.

This is simple if you just play thumb (not second finger) for the first 6 notes.

Yes, from what I can gather the 2-5 1-4 fingering is pretty well set in stone for each run.

The left hand part is quite easy and it may be possible for it to help. From videos I notice players don't opt for that, and do the RH part with just the RH. I'd like to use just the RH even if just to tackle the concept.

The first run falls effortlessly off the RH fingers played legato. My hand can stay almost completely relaxed on it.

Then immediately after the first run jumping the hand to the second run, the biggest challenge for me is giving the first 3 chords their correct time, especially without bumping C# with my 2 finger on the first C+A chord. I find if, after the first run, I bounce my hand slightly higher and then land 2-5 more straight down on C+A it helps me avoid bumping the C# (I'm landing my 2 finger towards the top of the white key in preparation for the next chord). For those first 3 chords my fingers are spread and tensed in order to hit the correct notes well without bumping others, and then relax going into the next 5 chords.

For the third run, I land 2-5 on D+Bb with my 2 finger between two black notes (for lack of a common term? fingers more towards the back of the piano). My fingers are locked between black notes for the first 4 chords, fingers spread and tense for nearly the whole run. Going from 4th to 5th chord I have a slight tendency to jump back rather than legato slide back, I'm not sure which I should aim for.

For the fourth run, the first 4 chords are easy, but going from the 4th to 5th chord my hand wants to lift up, same thing going from 6th to 7th chord. I find if I don't lift my hand slightly I tend to brush against wrong notes.

My biggest problems seem to be coming from the 3rd and 4th runs. So now I'm wondering, am I doing anything terribly wrong? Am I playing the 2nd run correctly? And for the 3rd/4th runs should I be playing legato by sliding fingers? Or let my hands do small jumps to quickly get where they need to be? Or perhaps I'm missing something else.

Thanks for reading my wall of text

Not exactly sure if I completely understand. I am trying the third run using the thumb more, here's what I'm seeing so far.



Initially this is the fingering which would make the most sense to me, assuming we're using the thumb repeated some.

edit: after running through it a few times using the thumb more, I can't help but feel like the original 2-5 1-4 actually feels better, as well as staying consistent with the other runs' fingering. Perhaps I'm doing it wrong.

This is all a dependent on hand size. A really big hand would not need the little extra shift to the right that one gets using only the thumb for the 3rd phrase (except the last Bb; use 2 there).