Every bicycle trailer has four capacity ceilings — the trailer’s own maximum load, its per-seat child rating, the hitch and bike rating, and the legal standard — and the lowest one always wins.
Load a trailer past the wrong number and the failure isn’t gradual: the hitch lifts, the rear wheel washes out on a turn, or a seat rated for 49 lb takes 60. What follows is the actual rating stack for the two-track child trailers sold in the US, the two standards that set the outside limits, and the loading order that keeps the whole rig inside every rating at once. If you’re still deciding which model suits your family, the tested roundup of the best bicycle trailers we’ve tested pairs well with the numbers below.
What Sets The Real Maximum Load?
The practical limit is the most restrictive rating among the trailer, the hitch, the towing bike, and any legal standard that applies — never the biggest number printed on the box. Manufacturers routinely rate their own trailers below the ceiling a standard allows, and when a bike maker’s hitch limit is lower still, that lower figure governs.
Seat ratings work separately from the box rating, and this trips people up constantly. A trailer rated for 100 lb total may cap each child at 49 lb, so two 55 lb kids blow the per-seat limit long before the gross weight looks wrong. Weigh the loaded trailer — passengers and cargo together — against the stated maximum total mass, and check each child against the per-seat figure before anyone climbs in.
If the trailer mounts on a rear carrier or rack with its own limit, subtract the trailer’s vertical (tongue) load, typically 2–8 kg, from that carrier’s capacity.
What Do The Standards Actually Allow?
Two standards set the outside boundaries. The European EN 15918:2011+A2:2017 standard covers two-track cycle trailers carrying cargo or up to two passive child passengers, sets a maximum permitted total trailer weight of 60 kg, and requires each child to sit unaided and weigh no more than 22 kg. For North America, ASTM F1975-15 is referenced as covering non-powered bicycle trailers with one or two child passengers and a maximum accessory load of 45.4 kg (100 lb) for a trailer without brakes.
Read the scope lines carefully before applying either. EN 15918 covers two-track trailers only — it excludes trailer cycles with pedaling passengers and certain single-wheel or professional trailers, so a racing or cargo single-wheeler follows its manufacturer instead. A separate manufacturer FAQ notes that many reputable builders suggest roughly 45 kg of trailer weight for a normal bicycle with a good braking system.
| Standard Or Trailer | Stated Limit | What It Covers |
|---|---|---|
| EN 15918:2011+A2:2017 | 60 kg total | Two-track trailers, cargo or two passive kids ≤22 kg each |
| ASTM F1975-15 | 45.4 kg (100 lb) | Non-powered kid trailers without brakes |
| Thule Coaster XT (US) | 2 × 49 lb kids, 100 lb capacity | Two-seat child trailer |
| Thule Chariot Cross single | 49 lb child, 75 lb capacity | Single-child carrier |
| Thule Chariot Cross 2 single | 48.5 lb child, 75 lb capacity | Single-child carrier |
| Thule Chariot Cross 2 double | 2 × 49 lb kids, 92 lb capacity | Two-child carrier |
| Thule Trailer Kit instructions | 34 kg single, 45 kg double | Kids plus cargo combined |
How Do You Load And Weigh It Correctly?
Weigh the trailer after it’s loaded, not the cargo before it goes in, because the trailer’s own mass counts toward the total.
- Weigh the loaded trailer against its stated maximum total mass and its payload rating.
- Check each child against the model’s per-seat weight limit before they get in.
- Subtract the trailer’s vertical load from any bike carrier capacity it hangs on.
- Compare the trailer rating, the hitch rating, the bike rating, and the standard — then load to the lowest number of the four.
When a bike or hitch limit falls below the standard, the bike wins every time. A trailer pushed to 100 lb behind a bike rated for less than that overloads the frame, brakes, and rear wheel, which is how hitches fail on descents. Falling back to a 60 kg (132 lb) legal ceiling on a bike that never saw that number approved is the same mistake wearing a regulation’s clothes.
You’ll know the load is right when the trailer sits level, the hitch stays seated over bumps, and a hand-push test rolls it without the coupling lifting. Before any trip that adds a second child, gear, or a new bike, do the four-way comparison again — the answer changes when any single rating changes. Getting this wrong rarely announces itself until a corner, a curb, or a hard stop.
FAQs
Can I exceed the per-seat child rating if the total trailer weight is still under the limit?
No. The per-seat limit and the total capacity limit are separate constraints, and both apply at once. A trailer rated for 100 lb total may still cap each child at 49 lb, so two heavier kids break the per-seat rule even if the combined weight looks fine. Always check each child against the seat rating individually.
Does the European 60 kg standard apply to trailers sold in the US?
Not automatically. EN 15918 covers two-track cycle trailers in the European market, while North American trailers typically follow ASTM F1975-15 or the manufacturer’s own rating. If both a standard and a manufacturer limit apply, the lower figure governs regardless of which region you ride in.
Do I need to count the trailer’s own weight toward the load limit?
Yes. Total capacity figures cover the loaded trailer, not just what you put inside it. Weigh the loaded trailer against the stated maximum total mass rather than estimating from cargo alone.
References & Sources
- iTeh Standards. “SIST EN 15918:2011+A2:2017 — Cycle trailers, safety requirements and test methods.” Source for the 60 kg two-track trailer limit and the 22 kg per-child rating.
- Thule. “Bicycle Trailer Kit Instructions.” Source for the 34 kg single and 45 kg double capacity figures including children and cargo.
- Thule. “Thule Coaster XT.” Source for the Coaster XT per-child and total carrier weight ratings.