Consider this possibilitity. You're leaning on the bars, maybe on the tops, which means the stem and bars are torqued down and forwards, so the stem is pulling on the front of the fork tube. If the expander is a wedge, and the wedge is on the back side (near the back of the bike), then it's pushing on the back of the fork tube. In that particular case, 22.2 mm, 22.0 mm, even 14.0 mm stem, it matters not. There should not be a problem.
What WOULD matter is if it used an expander PLUG, not a wedge, or if the wedge was on the FRONT (not the back) of the stem, OR if you are a track racer or big into "pulling" back on the handlebars during sprints. In these cases, the stem might rock inside the tube, creak or whatnot, and the full length of aluminum would take many (larger) stress cycles.
So in summary, if you are a recreational rider and it's a wedge stem with wedge on seat-side of the stem, then I wouldn't worry.
I'd like to hear from someone who's had a problem in this case ???
- Don Gillies
San Diego, CA, USA