other types of wheels. Solid metal wheels with solid treads, such as dolly wheels. Extremely durable but rough riding and usually slow due to small diameter. Standards A voluntary European standard (EN 15918) for two-wheel bicycle trailers was published in September 2011. This standard applies to trailers carrying cargo and/or up to 2 passengers, and enforces a maximum gross weight of 60 kg. There are many safety-related requirements, including restraints, structural integrity, stability, small parts, sharp edges, etc. The North American standard, last updated on December 27, 2016, urges a maximum accessory load of 45.4 kg to not be exceeded; the standard applies to non-powered bicycle trailers carrying 1 or 2 children passengers. See also Outline of cycling Trailer (vehicle) Cargo bike References External links Angus adventures "Which trailer is right for you?" Cycling equipment Utility cycling