Would a 7speed altus shifter work with a 7speed tourney rear mech?

from what I can gather from google searching is everything shimano under 9 speed has the same pull ratio

Yes.
Anything (except rare 8 speed Dura Ace?) is good from 7-9 as long as you match #speeds shifter = #speeds cassette.
There are more, but 7 to 9 is easy to remember.

There's a website with pull ratios for almost every shifter and DR out there, but I can't seem to locate the link right now. I'll keep looking but my gut says they should work. Maybe someone else on here has the link and can post it again.

https://docs.google.com/spreadsheets...#gid=847158527

​​​​​​https://bike.bikegremlin.com/1278/bi...compatibility/

6 through 9 has the same pull ratio.

Minor correction: 6, 7 and 8 Dura Ace all had pull ratios not directly compatible with all the other SIS components.

Generally yes but I wouldn't put a bunch of money towards a bike equipped with tourney. Save your money for a practical bike for your riding with decent shifting well beyond 8 speed.

its a beginner bike I picked up for £25 for my girlfriend. I have two 10speed and one 9speed equipped bikes and going to stick 11 speed on to an early 90s British eagle shadow as my next project, personally I wouldn't call a £20 altus shifter an upgrade more of a sidestep - still appreciate your comment though

Always be careful of a bike like that for a beginner, it can be an easy way for someone to think they dislike cycling because the bike doesn't perform well or feel good. Hopefully your girlfriend understands this and won't get turned off. We want more cyclists not fewer : )

Also I didn't call Altus an upgrade (nor am I am saying it is not) I just stated don't put money towards the bike. Just to be on the level. A nice 531 bike could do well with a good upgrade, CUES looks like a good upgrade and I am considering it for an older frame as well that or Microshift AdventX/Sword and building a cool 26" gravel bike.

Completely get what your saying but at the same time if you dont like how your bike looks you probably wont ride it as much, I was going to get her a sweet ragley but she likes pendletons so thats what I got her. They come with gripshift which in my opinion is complete crap and that alone could put her off cycling hence the cheap altus quick shifer as a temporary measure, My hope is that she will enjoy it on flat ground for a few months then we will try some gravel / light offroading and she will see the benfit of a capable hybrid / mtb and a decent groupset and ill get her a nice upgrade, cant expect anybody to enjoy cycling with their first experience is gripshift! Doubt she will have any care about how the bike actually shifts until she has ridden it for a few months in which case if she still wants the pendleton ill throw a cassette rear wheel and probably sram x5 on it. Yes id rather her have a cooler bike but if thats what she likes then ill have to deal with it for a while, I know how picky I can be with how my bikes look so I have to respect it

can always throw some semi decent parts on it while she uses it and swap the crappy ones back when it comes to selling it

also theres something about rolling a turd in glitter that I enjoy