I'm guessing neither of you climb fast enough for the draft to matter. Unless it's a windy day coming down the slope against you.

Pros climb fast enough it does matter if you can surge and form a gap or not. They'll even move close to the fans and risk crashing to help negate the draft for the guy behind them.

Meaning, in your case, it likely is all about w/kg only.

One thing worth noting though, for stuff like this under an hour it is worth being able to rev it and back off. Mountains aren't perfect 6% the entire way, on the dot. You save more time spending more energy on the steeper parts than the shallower parts. If you can over-rev for 30 seconds around a switchback and then hold on just below your limit you'll do better than a guy who can only just "TT" the entire hill.

I suggest you watch some Gaimon "best retirement ever" videos, maybe the one where he won the hillclimb US champ jersey. He talks strategy in these.

If it were me, I'd likely wait a few minutes and the first time I hear you click a gear down for a steeper part I'd keep it in and gap it. It's usually a few free seconds catching it on a gear change.

yeah last year we averaged around 20km/hr so not much, if any, drafting benefit.

I don't understand how you can have a similar FTP, he be 10 pounds heavier, and you lose 3 minutes to him. If you lost 3 minutes, then I'm guessing last year you were both riding solo and there was no drafting between you two? Or was he drafting other guys and you were solo? At 20 km/h, there is a definite draft benefit. I would say somewhere in the neighborhood of 20+ watts.

Anyway...lets do some math. I'm going to assume you're 150 pounds and your buddy is 160. Both of you have 20 pounds worth of bike, shoes, helmet, clothing, bottles, etc. So your total weight is 77.1 kg and your buddy is 81.6 kg. In order to sustain 20 km/h at 6%, you're holding around 307 watts and your buddy is doing 322.6 to do that same speed. But if your buddy is 3 minutes faster than you, he's actually going 21.3 km/h. 20 km/h for 10 km is 31:04, so he would have gone 28:04. To sustain 21.3 km/h he's pushing 349 watts. Even if he was drafting someone the whole time he's probably doing 325+ watts.

So something is wrong with the information you're giving us. You don't have similar FTPs. Typically I would say if someone is beating you up a 10 km hill by more than 3 minutes than there is no amount of tactics you can use to win. The other guys is simply way stronger than you are. I don't know how you're beating him on flat TTs unless he's an aero brick.

Maybe this could help:
https://blog.wahoofitness.com/...wnerlal_hillclimbing

Nah, that would matter some at that point.

I'm used to the question being from folks climbing in the single digits mph. If it's into the double digits, worth it.