Hi

Trying to establish if a stretched out bike may cause a sore lower back.

I’m about to press the button on a Canyon Ultimate CF to replace my old Planet x SL. I’m opting for a small, which is pretty much 1 cm less in tt and reach than my planet x. Given all angles are the same an extra 10mm length stem would I assume give me a very similar position. (110 mm, currently have a 100mm)

Trouble is I currently get a bit of back pain after an hour of so on the bike, and a few internet searches appear to show that it may be because I am a bit stretched out. Would this be a possible cause, or conversly could it be that I’m currently to cramped and need to space myself out a bit more?

Initial plan was to just go with experiment with stem lengths when I got the bike, but I see that its a non standard steerer tube size, so thats not really such an option. No pics of me on the bike to really help make a judgement either Im afraid, but if I’m honest the current bike feels good until I hit the hour mark…

Any help would be useful

ta