Cy, when you state that riders should use a 35mm stem, what forward offset of grips to steerer does that equate to on your personal, test or demo bikes? Either horizontally or perpendicular to the steerer. Does that make sense?
I ask because I’ve noticed that once you’re down to really short stem lengths, the backsweep of a bar becomes significant, as do the upsweep and rise. Like, for instance, if you have a 40mm rise bar and position it vertically, you’re extending the lever of the stem by ~20mm. If you position it with the rise in line with the steerer tube then you keep the lever length the same, as indeed if you had a flat bar with the same sweep figures and used 40mm of steerer spacers to raise the bar to the same height.
You are quite right that you need to be a little more careful with bar roll with short stems, but our 35mm recommendation is based on the fact we all use either Cotic Calver bars or Burgtecs which have 8-9deg of backsweep, so nothing out of the ordinary. I did fall foul of this last summer after missing my mark when putting my bike back together after a trip and wondering why I couldn’t get over the front and the steering was really light. I had the bars rolled back far enough that I effectively had a zero stem. Rolled ’em forward and again and the bike ‘switched on’ again. If you do like bigger sweep bars, you should defintely get a long stem though. If you put a string across where the middle of your hands go, on a Cotic the string should be 15mm or more in front of the steering axis.
