The mtb bb might be wider but on 68 mm mtb bb shells you still need to fit three 2.5 mm spacers. So I assume even if they are wider, you can still make it work on shorter road axles with thinner spacers like the ones from velosolo. I assume the plastic preload cap can take out a little play too. All this is just assumptions though since I only have HTII on mountain bikes.
The mtb bb might be wider but on 68 mm mtb bb shells you still need to fit three 2.5 mm spacers. So I assume even if they are wider, you can still make it work on shorter road axles with thinner spacers like the ones from velosolo. I assume the plastic preload cap can take out a little play too. All this is just assumptions though since I only have HTII on mountain bikes.