Nieuwelingen are subject to many restrictions. First is the gearing: they need to ride a gear smaller than 6.94 m (or equivalent to a 52X16) on the road, track and for cyclocross. There are no gear restrictions for mountain bike or BMX. Although Shimano makes cassettes that start with a 16 cog, most riders uses spacers and a derailleur adjustment instead. A derailleur adjustment alone is not allowed.
A 16 cog on the inside won't fit in many newer carbon frames, so the spacers are an easier solution overall. Gear checks are common for stage races and interclub (IC) races, but far less so for regular events, often called kermesses by US riders -although not all are kermesse races.
Nieuwelingen are also restricted to races no longer than 60 km for the first three weekends of the season and 70 km thereafter. For IC races the max is 80 km. Cyclocross events are limited to 30 minutes max. Mountainbike events are limited to 1h15 minutes.
Nieuwelingen are allowed a maximum of three races per week, with a maximum of two in the same discipline (road, track, cyclocross, mountain or BMX). The road season starts on Feb 1 and lasts until mid October. Track is year round. Cyclocross starts on Sept 1 and runs until March 1. Mountainbike and BMX are year round, but mountainbike is mostly a summer sport in Belgium.
All weeks start on Mondays and end on Sundays.
The kalenderkaart is used to keep track of the number of races. Belgian riders have a race-log instead. The kalenderkaart has 3 spots per week to allow for official entries. Each time you race the official will fill out a box.
Stage races (rittenkoers) are counted as one race, but one is only allowed to compete in three events per calendar year. Nieuwelingen also can't compete the day before and up to four days after a stage race.
Nieuwelingen cannot ride disk wheels in time trials. They need to ride wheels with a minimum of 16 spokes per wheel.