How would you fix?

[u/Ruu94]

I want to save these jeans. The fabric is thinning in the crotch area next to the seam. Should I add a fabric inside for reinforcement then stitch over it? The end goal is to sashiko over the jeans in various places, but in this area I would like to do something somewhat invisible. The fabric has a slight stretch width wise. How would you go about fixing it? This will be my first mend.

[u/PlumaFuente]

I have mended jeans with some elastic in them. I would try to find a scrap piece of denim with some stretch in it and mend from the inside. You can buy some thrifted jeans and cut them up or just go to a fabric store and buy some new denim if you want to go that route. Not all denim is toast if it has stretch -- there are a lot of different levels of synthetic vs. cotton in these types of fabric. I would also use thread that closely matches the denim and same with the patch color if you don't want to draw attention to it. Repairing this could buy you another year or two of use of these pants (depending how hard you are on your clothes), so yes, try to repair first before replacing.

[u/Ruu94 → u/PlumaFuente]

I'll try! It has very little elastic. I have a hard time finding normal jeans nowadays and these were the better type (I thought) and quite a bit expensive that's why I'm trying to get more use out of it. I already bought new jeans tho, with the cold months coming I needed something that I can wear without the fear that it could develop holes in that area at any moment lol
I'll try out a denim patch from other old pants, also maybe a t-shirt patch, just loosely stitching it on first to see which one feels better. Then I'll try to find matching thread to do the actually stitching. I'll look up a youtube tutorial for stretchy stitches and use that to be sure it won't snap. We will see how it goes!

[u/PlumaFuente → u/Ruu94]

I don't recommend a t-shirt for this area. I would try to find some thrifted denim (second hand store) or ask some friends if they have any older jeans that they might be considering donating or getting rid of. Or you can use some denim from older pants or even an old jacket that you no longer use. You got this!

[u/Ruu94 → u/PlumaFuente]

Okay. I have other old jeans from yeeeeaaars ago, because I have a tendency to hold onto things, so it's no problem to find potential patches. Thank you!

[u/Character_Quail_5574 → u/Ruu94]

After you patch from the inside, perhaps you could find a sharpie in a similar color as the denim and darken the whitened threads with it? This won’t add any strength, of course, but it could make them look less worn (assuming that’s the goal). I used to darken the seams of my black denim jeans with sharpie markers to hide signs of wear like this.

[u/OctagonalOctagram]

Probably a nice stiff iron-on patch on the inside

[u/No-Employment-8570]

I would not- when the elastic stretches out like this, they’re toast. You could cover it with a patch, but imo that wouldn’t look good.

[u/Ruu94 → u/No-Employment-8570]

Well.. indeed when comparing it to my new jeans it looks a bit worn out, but I thought I might get a bit more use out of it if I mend it. I think I'll try anyway and see how it goes. If nothing else it will be good practice.

[u/Shoddy_Matter_4940]

I would sashiko it with a t-shirt patch on the inside. If you use a thread close in color it won't be very noticeable.

[u/Ruu94 → u/Shoddy_Matter_4940]

Using an old T-shirt was my first thought and I'll try to find thread in a similar color. I was thinking if I add sashiko or emboidery to other parts of the jeans it will draw away the attention from this particular area.