So your sit bones are on the two tips of the ISM? That’s not how it’s meant to be sat on, but if it’s comfortable for you, sure. It’s really to meant to be sat on just like an ordinary cutout saddle, except for the fact that there is no nose - that doesn’t mean you should move forward on the saddle.
Illustration
Also, if the bike fit is correct and comfortable, you should be able to sit on your sit bones on an ordinary saddle, with a horizontal back and hips closed while pedaling. I’m quite certain that ISM really has two purposes:
- Avoid breaking UCI/ITU rules.
- Compensating for poor fit. If your saddle is too far aft, lacks cutout, saddle is too high, handlebars are too far away, you’ll have too much weight on your perineum and want relief (unless pushing 400 W because you’re floating then).