Anybody have shoulders that "turtle" during medium efforts?

[rothwem]

I had knee issues last year, so I got a fitting for my bike where the guy basically pushed my seat way back to achieve something approximating KOPS, and he raised the bars roughly 35mm and put me on a 30mm shorter stem. Basically, he rotated my position backwards by a few degrees, and kept my hip angle roughly the same. My knees do feel better and I feel like I'm using more of my leg and glute muscles instead of just my quads, so I at least consider that part of the fitting to be a success.

Since then, I've noticed something strange when I do medium efforts, around 100-110% of threshold. Basically I find myself pulling my shoulders up, tucking my head and locking my arms. I conciously relax my shoulders and bend my arms when I realize I'm doing it, but I'm never sure how long I've been doing it for. I think it has to do with when I had low bars, my arms were more or less straight but my shoulders had to be extended to reach the bars that were way out and down. It also could be some sort of muscle imbalance that I need to strengthen away in the gym.

My bike handles like shit in the new position and I want a new frame to get the wheels in the right place under the contact points, but if I need to change my fit, I want to do it before I buy a new frame. Any thoughts?

[zefs]

Why not mention it to the fitter? The harder you go the more you need to relax.
Have you tried core strength exercises?

[rothwem]

Why not mention it to the fitter? The harder you go the more you need to relax.
Have you tried core strength exercises?

Yeah, I'm thinking about it, but I've moved since I got the fitting and he's now a 3 hour drive away and I'm sure he'll want more money to take a look at my position. It might be worth it if I can't fix it for free with input from the internet though.

As for core strength, I've been doing 2-3x a week in the gym, doing some light upper body work and a lot of abs/hamstrings/glute type of exercises since my knee issues were related to me over-recruiting my quads and basically not using my hamstrings/glutes at all.

[zefs]

I guess this happens because you sit more upright and with less reach, try either a longer stem or less spacers?
When you place your hands on the hoods can you see the front wheel's hub?