I picked up a new shorter stem online to try on my Seven steel roadie as after a year in the saddle with this bike and my ability has increased I'm realizing it's a tad big for me, a 58 with my two other roadies being 56s. I'm going from 110mm to 90mm. When I went to put it on I discovered the new stem is sized for a 31.8 bar and apparently I've got a 25.4. Looking online I see very few offerings in the smaller size so my first question is is there a shim that can be used to make this stem work? The second question is, the Seven has a "seven wound up" fork, the bike being from 2004 which I picked up used, how do I tell if it has a carbon steering tube? It was black and looked like carbon but this is all new to me. I ask as most of the inexpensive 25.4 stems said not to be used on carbon steerers. A third question comes up, should I be using a torque wrench when tightening the stem to the steerer? I'll be heading down to my LBS later but thought I'd try here first.
Thanks in advance