CyclingRoberto:
Is it unmanly to use the new smaller half-size shopping carts?

As long as the the knee to axle measurement is right. I’d recommend a fit kit anyway to make sure the seat is 1/3 of the way back. That’s harder to determine on a cart and a professional bike shop employee may be the only one with the training and experience needed to triangulate the variables. I’d also say it isn’t the size of the cart that matters, but the slope of the head tube that defines a rider.