Riser vs low riser

mb london

Lookimg to pimp my ride with some carbon bars, unable to find a perfect fit but have found something which is a 30mm rise vs my current 15mm rise.

Question - in real world riding am I likely to notice the difference that much ??

supersonic

Yes, a little. But given you can alter the height with steerer spacers (assuming you have any to swap around) then you can tune the height anyway.