140 is actually pretty easy. Steady 20 hrs weeks for about a month if you're already in the 120's.

I know UMD made 160's once I think. That's nuts - also unsurvivable for me. 140 is my magic number. I do best in the 115-120 range, and am usually floating pretty high if I peak in the 120's and drop just below 120 for racing.

It's a long road to get there though. If you want to survive, a 4-5 pt per week increase is pretty much max. I've done 7-8 pt increase weeks but end up with a week totally a wash the next, so the two week avg is still 4-5 /wk.

You need 16-17 hrs per week of a mix of intensities to get 4-5 pt increases after about 115ish. To get 4-5 point increases after 120, you need 20+ per week. You can still increase at 2-3 per week on 17-20 hrs per week, just takes longer.


Edited to add commentary:
This sort of increase requires a great deal of consistency. 6 days per week, every week, every month. You can wipe out a full week's 4 pt increase with two unscheduled days off. You end the week with 0 increase in CTL (though not necessarily increase in fitness! ***** HIGHLIGHT **** HIGHLIGHT ****) CTL does not equal FTP, it equals endurance and recovery. That means you have to stay healthy, in a routine, and committed to it.

Most guys see the same increases in fitness (all zones) with half the CTL. Fitness increase is a much greater response to content - not quantity.