PULLED: Dura Ace RD-7900 what have you?

Years after the hive mind moved on from 1xn - I’ve discovered 1x7 on my commute bike and become a convert to ‘more than one gear’. I now want to try a 10 and dick around with cassettes and generally tinker. Ta. P.

Mtb or road?
Shimano or sram?

First go will be with a 5600 cassette and a n/w 44t ring. Mostly this bike will be roads, but options to take it somewhere a bit more rutted.
(Does the manu matter for these things? I have no idea!)
Thanks...

Cassette will be cross compatible between Shimano and SRAM.
Shifters and mech need to be same though (as far as i am aware)
For instance:
I have 5700 10 speed shifters and a shimano 9-speed non clutch, shadow xt mech (M772). This is compatible. But modern 10-sp shimano derailleurs (i.e. Tiagra) have the same cable pull ratio as the 11-speed shifters (i think), and not the old 10-speed variants.
For SRAM, i think is much easier to match the cable pull etc required, and most of their stuff now is 1:1 ratio so all works well. No expertise here though.

For the 44t narrow wide, i used a SRAM Apex 1.

So ultimately, if you have some shifters already then start there with that and look for what is compatible. Otherwise, start from scratch i geuss

https://www.artscyclery.com/science-behind-the-magic/science-behind-the-magic-drivetrain-compatibility/

This is more comprehensive actually: https://en.wikibooks.org/wiki/Bicycles/Maintenance_and_Repair/Gear-changing_Dimensions#Rear_Shift_Ratios

Ah, that’s really helpful - thanks. I’d clean forgotten how the pull is an issue.

The 1x7 is using a DA7700 bar-end/thumbie in friction shifter mode with a M780 rear. For the 1x10, I’ve got a DA 10-speed bar-end that I don’t think has a friction option - so it will need a compatible rear. Ugh.

Okay. More reading needed!

Presumably that DA 10sp bar end shifter has a 1.7 pull ratio, in which case the 9-sp rear mechs will work (e.g. M772), but don't buy shadow plus mech which is the clutch version and incompatible.
How old are the bar ends?

Also apologies for basically hijacking the wanted ad, i'm afraid i don't have a mech for you!

Okay. Bar-ends be damned. I need a DA 7900 rear...longish cage would probably be better. I’ll consider anything tho! Cheers...

Pulled not for here.

(did get a M781)