Firstly, I tried to put it on while wearing a bra - very fiddly - but I found you could feed it around the straps and do it up before putting on your bra - it's just a bit of a faff to get your bra on then, getting that bit behind your head, doing the bra up and then pulling the strap down your back to the most comfy spot. I wonder if the racer strap could be longer? My back is quite narrow and I had the strap fully extended, but it still pulls the bra straps so that they twist and could be seen under your clothing (as is the racer strap if you place the strap adjuster on the outside). Having said that I realise that you need it to sit in-between your shoulder blades. I will keep these as they are at least helping to keep my bra straps from falling off my shoulders!