Just to add to this ... I mentioned that this is not the first time I've experienced this pain.

The first time was when my distances started increasing but I was riding bicycles that were way too big for me. Then I went to bicycles that fit me and the pain went away, so I thought the problem was solved.

It returned when I got up over 400 km on my Giant in 2001, but again I thought that maybe I was a bit too stretched out. Although my Giant fits me for height, the reach is a bit long.

So I got my Marinoni and all was well till the Paris-Brest-Paris in 2003 when it returned ... but it went away soon after and I don't recall that it bothered me again until 2015.

In 2015, I did a climbing ride on my titanium ... and it was back. But then I adjusted handlebars and so on and it seemed to go away ... till now, or rather, early March. I have been riding the titanium again on long rides ... so maybe it is a factor in this equation.

I was also in uni walking decent distances with a heavy backpack in 2015 when it flared up ... so ... who knows ...