Not really a cycling expression, but I did hear JaJa say it on France TV the other day, so it is applicable. If you are dans les cordes, you are ‘on the ropes’, which in cycling terminology usually means that you are hanging off the back of whatever group you are trying to hang on to, but not for long.
If a person is dans les cordes, this is nearly always a bad thing, unless you are Muhammed Ali in Zaire.
The Vicious Cycle 
Rope a dope it was called. Is there an equivalent technique/strategy in cycling? Maybe Pogacar has been using it a bit to lure Vingegaard into thinking he’s at the end of his rope. Or vice versa
I hear them say ‘bluffer’ a lot, but it seems that’s not the case in this Tour. Exciting week ahead.
I heard a commentator use the phrase ‘crystal cranks’. Is that one that means something to you?
That sounds like something Adam Blythe would say. He comes up with a few Belgian doozies.
Otherwise, no. It doesn’t ring a bell.
It was David Millar on ITV. He applied the term to people riding at the back of breakaways and not taking their turn apparently because they had to pedal very gently to avoid breaking their valuable crystal cranks. We were amused. I have crystal cranks all the time these days.