Clark W. Griswold
Join Date: Mar 2014
Location: ,location, location
Posts: 13,516
Bikes: Foundry Chilkoot Ti W/Ultegra Di2, Salsa Timberjack Ti, Cinelli Mash Work RandoCross Fun Time Machine, 1x9 XT Parts Hybrid, Co-Motion Cascadia, Specialized Langster, Phil Wood Apple VeloXS Frame (w/DA 7400), R+M Supercharger2 Rohloff, Habanero Ti 26
Mentioned: 54 Post(s)
Tagged: 0 Thread(s)
Quoted: 4353 Post(s)
A new bike will probably get you wider tire clearance meaning more comfort which is a good thing. Low end carbon vs. nicer groupset I would probably go nicer groupset but me personally I wouldn't really be considering aluminum or carbon anyway.
I would make sure your old bike is in good order and having a receipt saying it was recently tuned can help bring a little more to the table. A bike should be tuned up at least once a year or at the very very very least looked over by someone who knows what they are doing. Leaving it like that for so long isn't good care and maintenance and not a habit you should get into.
The most important upgrade is getting a fit and I would recommend that to anyone back pain or not but especially if back pain. Do that and then you can get your new bike or keep your old bike and upgrade it because you will have some knowledge and your fitter can help steer you in the right direction for comfort.