I'm not sure this is worth mentioning, but I've bumped across a lot of advice on the web and in magazines about keeping the original seams when you hem up RTW jeans. This is a lot of guff about folding this way and that way and ending up with an internal ridge of extra denim around your ankle.
I just want to be a lone shout-out on the web of: "don't bother!"
I had some new jeans (lovely high waisted ones too!) that needed the hem taken up.
- I bought some gutterman gold top stitching thread. If you look at most RTW jeans there are different coloured threads on them, so an exact match is unnecessary.
- I used this thread both on top and in the bobbin.
- I used a sewing machine needle especially for jeans.
- I used a roller foot.
- I lengthened the stitch length on my sewing machine to look more like the existing stitching on my jeans
It went well and easily. No need to mess about and have lots of funny stuff flapping around the inside of your jeans hem. The roller foot was nice, but probably not strictly necessary. A little tug from behind as the foot is coming up on the bump of the vertical seam, but that is about it in the way of challenges.
Final thought: Don't over-complicate things!
