Any tips on getting good leg drive?

Hi - I'm mostly a touring paddler, but have been getting into the wing paddle and trying to up my general fitness level. I paddle an Epic 16X and recently got a KayakPro erg on Craigslist.  

I find on the erg -- and even more so in the boat -- that I don't feel like I'm getting good leg drive.  I never get much of a burn in the legs and glutes after going hard.  By contrast on a rower, I *definitely* feel it in my legs and glutes after rowing hard (and while rowing hard).

Any suggestions for what I'm missing?  I've definitely struggled to find the right knee bend where I feel solid connection to the footboard but don't feel scrunched up or too loose in the legs.  Things get trickier in the boat, maybe due to the wrap-around seat or a less elevated seat (the KayakPro seat seams slightly elevated compared to the Epic seat)?

PS, anyone get fatigue in the delts while erging? Only happens to me on the erg, not in the boat.  Using a carbon fiber shaft on the KayakPro.

Thanks!

More difficult to achieve appropriate leg drive in a sea kayak than in a surf ski or on a kayak erg due to the inherited position the sea kayak puts you in: seat to heel ratio is almost non-existent, footplate and toe pedals on many sea kayaks are non-existent. Not sure if your 16x has the old school toe pedals or a dedicated footplate like skis. The back band as you mention can be problematic too. If you have a proper set up in a ski, we don't use the back of the bucket to necessarily help with leg drive. We simply use as another point of contact. The awkward position of splaying you legs or getting the appropriate knee height is difficult due the smaller cockpit in touring sea kayaks as opposed to K1's or the old Westside Racing Kayaks where the ergonomics of the seat and cockpit do not impede leg drive.   You have identified the problems. 
Once you upgrade to a very stable ski like the Think Ace or others, you will then come to realize the leg drive your desire. Remember leg drive is only good if you are STABLE!  The first that goes when you are unstable is leg drive. The more efficient paddlers have excellent leg drive in rough conditions. Rough is relative but you get the point. 

I was wondering something related, which is whether I'm rotating enough at the hips. I know that my shoulders need to rotate about 60 degrees relative to the boat in order to get a good forward catch, but I find it very difficult to tell how much of that comes from my hips vs. how much comes from waist rotation. Yes, I can see my knees go up and down but I can't tell how much waist rotation that causes. At the shoulder level it's fairly easy to observe whether more rotation would be beneficial or not, but at the hip level even with a camera I find it impossible. Any tricks?

Thanks for the reply.  What do you mean by  seat to heel ratio?

The Epic 16X is definitely not a surfski but it is friendly to paddling knees up due to it's cockpit and the fact that it does have a surfksi style footboard.  It's basically an Epic V6 as far as I'm aware except built  with a sea kayaing seat and closed cockpit.  I can paddle the boat knees up no problem and have no problem with stability in it.

I'm more concerned that I'm not working my legs enough on the erg, even though I'm clearly moving my knees.  I feel like maybe I have the same question as tve below - are my hips not pivoting enough?

First off make sure you are not lifting your heels. If your heels are moving then you are simply imitating leg drive. Leg drive comes from hip rotation not waist. Ideally your hip rotates in sync with your shoulders and arms. Think of shoulders being top of a picture frame and hips are bottom. 

2 drills I like for leg drive.
1 . Hold paddle low and close to body then paddle keeping shaft parallel to shoulder alignment, this will start leg rotation. Holding it low will help stability and cause rotation to be lower down at hip height rather than rotating waist.
2 Forget leg drive instead concentrate on rotating offside hip forward, when pulling on blade, to cause knee bend, trying not to pull hip forward on strap. Drive hip and leg will happen by reaction. Even remove straps to do this so you dont cheat

What you are aiming to do is rotate your  butt on the spot rather than simply pushing one hip then the other into back of the seat

The hump on a ski means it takes more mental focus to get proper rotation and leg drive happening compared to an ergo or flat bottom boat.

Super helpful!  Thanks!  

What you are aiming to do is rotate your  butt on the spot rather than simply pushing one hip then the other into back of the seat

I struggled with this for the first time this past weekend. I don't know if it was a balance issue as I learn to master my new v10 on lumpier water or the fact the my wetsuit is restricting my leg drive. Rather than "lift myself" out of the seat as I push forward, I found myself pushing into the back of the bucket, which as many have discovered causes uncomfortable chafing.