Stretch knit straps use a smooth, flexible fabric that lies flat against your shoulders and chest, unlike traditional mesh straps that can feel rough or dig in over time. They're typically wider too, which spreads pressure more evenly across your body. The result is a noticeably more comfortable feel, especially on longer rides where shoulder irritation can become a real distraction.
The trade-off is that knit straps run slightly warmer than mesh since they're not as breathable, so they're not the best choice for the hottest summer days. They also tend to come on premium bib shorts, so you'll usually pay more for the upgrade.
If you're doing long-distance rides, centuries, or multi-day events, stretch knit straps are absolutely worth it—the comfort difference becomes obvious after a few hours in the saddle. For shorter rides in hot weather, standard mesh straps work just fine and keep you cooler.