A cycling shoe that matches your usual size can still press on the forefoot or allow the heel to move during a ride. That makes foot measurements a better starting point than the number on the box alone. Lake Cycling recommends standing in the socks you intend to ride in and tracing both feet on paper. Measure from the heel to the longest toe, then measure the widest part of the foot. These two dimensions describe different fit problems and deserve separate attention.
Measure each foot independently because they may differ. Lake advises using the larger foot as the reference and recording dimensions in millimetres rather than rounding to a whole centimetre. Its own size chart recommends adding five millimetres to the measured length, but that allowance should not simply be applied to another brand’s chart. Width is equally important: moving up a length size may leave a shoe too long while failing to provide the right shape around the forefoot.
Measurements narrow the search; trying the shoe on decides the fit. The heel should feel secure, the middle of the foot supported, and the toes free of pressure against the front. A closure system cannot compensate for the wrong shape if it must be overtightened to stop movement. When ordering remotely, compare the size and width guidance for the exact model and check the return terms. If you can try it in person, wear the socks you will actually use on the bike.