Yup going fast with lots of SLAs is a wobbly affair for sure specially at that weight 20kg = 44lbs. Sounds like it has done you right though lots of miles you have on it. You have full suspension I can't wait to get there. I added another 10 lbs to my already 60lb bike just to get the other 12v for 48 and be able to climb some hills unassisted. Just that little extra and now hitting potholes at high speed makes the back end feel like it's made of jello. I doubt this frame would handle much more bike batts and me are 260lbs total likely near it's limit. I took it out in the rough today and at low speed on the dirt trails, what I built it for, its fine though. Got hold of one of those one wheel bob like trailers for cheap, think Nashbar screwed up, and will be putting extra batts there so I can make 40+ miles and see the sights as well as carry home the things and stuff I find along the way. Later