Bicycle bottom bracket assembly

A bicycle bottom bracket assembly having a rotational central axis, the bicycle bottom bracket comprising:

• a support member including a hanger mounting portion and a bearing mounting portion, the bearing mounting portion being configured to be at least partly positioned within a hanger part of a bicycle frame;
• a bearing unit including an outer race, an inner race and at least one roller element disposed between the outer and inner races in a radial direction with respect to the rotational central axis, the outer race being fixed to the bearing mounting portion of the support member;
• and
• a radially inward force reducing structure for reducing a radially inward force being transmitted to the bearing unit, the radially inward force reducing structure including a non-threaded outer circumferential surface of the support member, the non-threaded outer circumferential surface being disposed between first and second threaded outer circumferential surfaces of the support member.