I’ve just come across this after a bit of searching, interesting to see people feeling similar to myself.
I train pretty much exclusively on the flat (Lincolnshire UK) and have got my ftp up 290w and had always wondered why there is such a large discrepancy to my 264w at last test indoors. I rode today with one 20min climb and one 13min climb where the grade averaged around 15%, it shook me that I couldn’t hold anywhere near what I believed my ftp to be but then once over the tops I was back at 290.
Is there anything I can do to close this gap other than ride decent hills? I’m also wondering if I get better on the hills then it could maybe ramp my ftp nicely indoors too?