Need to know if this will work...
 

I've a bike friday and my rims are getting kind of worn. It's set up as a 7 speed. I am thinking of buying some Kinetix comp wheels which are 8 speed. My initial purchase would be the wheels and an 8 speed cassette.

I'd like to know if I can run those with my sram spectro 7 derailleur, sram spectro 7 gripshift, and my single front chain ring for a while. I'm trying to parse out the expenses as I save up for them. I'm okay with only using 7 of the gears, maybe using the limit stop to block the highest gear. Would this work?

Eventually I'd have to change the shifter (to a click shift). Would I need a different derailleur to accommodate the 8 (or more) speeds? Any other parts necessary?

Part of my consideration is that supposedly an 8 speed wheel can be upgraded to 10 later on, but the 7 is maxed out. In a perfect world, I would have a 1x10. My rear frame spacing is 130mm if that matters.

What are the things I have to buy all at once, and what I can purchase as time goes on? Thank you for your advice; I do the work myself and take it to a local community shop to have them check I did not screw it up.
I think it amuses them when the 66 year old lady shows up =).

It's close enough to work but not ideal, and it's a good idea to use a chain rated for 8 speeds.

It really depends on the wheel if a 7-speed wheel can go up to 10. There's some MTB hubs that had narrow freehubs for 7-speed. Freewheel hubs should really only be used up to 7 speeds. Some wheels put a 7 speed cassette on a 8-9-10 freehub with an adapter spacer. I couldn't tell you what your 7 speed wheel is.

You might be able to get away just changing the shifter, the chain and the cassette to 10 speed. These have to be purchased at once.

I'm not familiar with the parts you're talking about though. Spectro seems to be an internal gear hub system which is different from a derailer gear system, in which case you would have to change everything.

If the new wheel fits the dropout spacing of your bike, simply buy a 7 speed cassette and use a spacer. 7 speed cassettes are less expensive than 8 speed cassettes. If you want to upgrade to 8 or more speeds in the future, you can buy a cassette with more cogs. Cassettes wear out over time, so by the time you will want to change you will probably need a new cassette anyway

So i have a new 7 speed cassette right now - if I buy a spacer, it will fit the wheel which normally takes an 8 speed? That sounds like a plan!!! Then I can just buy the wheels for now, which is a pretty big expense for me.

If I later decide to put a 10 speed cassette on (to get to my ideal 1x10), would I need to replace the derailleur as well as the shifter? I don't know if derailleurs are "speed" specific.

I didn't realize there were spacers for this purpose - man, I love this forum!

If you have a 7 speed cassette, and not a freewheel, it most likely already has an adapter spacer. I don't remember seeing 7-speed only freehubs except for 135mm MTB hubs.

Derailers are not speed specific, but they are system specific, and it's not always obvious what is compatible with what, and I couldn't tell you what yours is because I've never heard of a spectro rear.

Make sure that what you have now is indeed a cassette, the limited information you provide about your bike isn't enough to know this, most bikes built in the last 10 years with 7 speed shifters use freewheels, not cassettes, not wanting to assume anything I don't know if you will need to buy a cassette

I recently bought and installed a Shimano Hyperglide HG 50. The cassette is all connected together except for the smallest cog. Came with a very thin spacer and a lockring. The old one didn't use the spacer, so I did not use it when I installed the new cassette.

The derailleur is SRAM, back before they got bought out I think. It was designed to work with the internal sram 3x7 hub but apparently also works with a regular cassette. Bike Friday said it is long enough to take up to a 34t cog.

7 speed cassettes fit fine on 8 speed hubs using a suitable spacer, you just have to be sure that your dropout spacing is wide enough

HG-50 is a cassette. It could be that the spacer just stayed on the freehub body when you replaced it, but if you're planning on replacing wheels anyways, just see if you can find the spacer again.

Double check the markings on the SRAM rear, it's not always the same as what it says on the shifters.

First four words at the top...

I did go back to the original question and corrected my answer

From the spec sheet for my bike

Deraillleur: SRAM MRX Shim compatable (SMR-10) 34tooth max
Rear hub: Shimano 7sp 36o FH compatable Rear Alloy QR
Shifter: SRAM MRX Comp 7sp right twist shift Shim compatable

If it's really MRX, then according to SRAM, it's the old Shimano standard. For 10 speed, you would need Tiagra 4600, not 4700, flat bar shifters. Microshift TS83-10 should also work.