If it helps, when I got my first 'proper' roady after riding a track bike for quite a while I instantly slammed my stem right to the base of the steerer, cut off the remaining steerer tube, put on an an 80mm stem and fitted an in-line seatpost because, like you, I felt like superman.
Biggest hipster error I have ever made.
2 months down the line, constant back and knee pain from having my torso and legs in the wrong position so back on went the 110mm stem and layback post... unfortunately however the excess steerer could not be glued back on.
As Dan says, stick with it... it's just your body getting used to this position... but then you probably already knew that.
As you were.
I did exactly the same as you with my first road bike. Chopped steerer (only because there were no headset spacers in the bloody box, it was 6pm and I was in a hurry to build the bike before I got locked in my workplace) and slammed the stem. I suffered lower back pain on long rides and attributed this to the long stem, so bought an in line seatpost and shorter stem. The inline seatpost was mostly for aesthetic purposes, and meant I could have the seat in a central position rather than all the way forward, which looked daft. Short stem stopped me stretching out like Mr Reeve himself. Instantly the back pain went...
On the new bike I had the same problem, but without the chopping of the steerer - 120mm stem, layback post, position of a flying bloke of Kryptonish origin. Stretching to reach the hoods and felt some serious back tension coming on after just one 20 mile ride, so the stem was swapped for a 90mm one which gave a more natural position and instantly eliminated the back pain.
Not sure what my point was or why I typed all that... erm.... yeh. But it's interesting to see that what worked for me, didn't work for you. Perhaps you have better-developed core muscles to support your spine while in that stretched out position...
I did exactly the same as you with my first road bike. Chopped steerer (only because there were no headset spacers in the bloody box, it was 6pm and I was in a hurry to build the bike before I got locked in my workplace) and slammed the stem. I suffered lower back pain on long rides and attributed this to the long stem, so bought an in line seatpost and shorter stem. The inline seatpost was mostly for aesthetic purposes, and meant I could have the seat in a central position rather than all the way forward, which looked daft. Short stem stopped me stretching out like Mr Reeve himself. Instantly the back pain went...
On the new bike I had the same problem, but without the chopping of the steerer - 120mm stem, layback post, position of a flying bloke of Kryptonish origin. Stretching to reach the hoods and felt some serious back tension coming on after just one 20 mile ride, so the stem was swapped for a 90mm one which gave a more natural position and instantly eliminated the back pain.
Not sure what my point was or why I typed all that... erm.... yeh. But it's interesting to see that what worked for me, didn't work for you. Perhaps you have better-developed core muscles to support your spine while in that stretched out position...