Rules & Categories


The Mangere Bridge Trolley Derby is open to EVERYONE. Whether you're One year old or One Hundred, there's a race category for everybody.

NIPPERS: The trolley driver is 5 years of age or younger on race day. 

(See below for rules specific to Nippers Category)


Trolleys can be entered in ONE of the following THREE categories:

ZOOMERS: The trolley driver is between the ages of 6 and 10 years of age on race day.

SPRINTERS: The trolley driver is between the ages of 11 and 14 years of age on race day. 

ROCKETS: The trolley driver is 15 years of age or over on race day.  

MONARCH OF THE HILL: The trolley driver is 15 years of age or over on race day.   

Corporate teams and adults are also encouraged to enter with the Monarch of the Hill category, so if you think you've got what it takes get building now. Entries in Monarch of the Hill may also be entered in ONE of the previous categories.


alex trolley derby

Race Day Rules and Trolley Design Requirements


As we are associating with the Nelson Trolley Derby that has been running since the 1960's, we are using the same race rules and categories that they have developed. These are tried and tested and ensure enjoyment and safety for drivers and spectators.



Drivers must have forward facing vision at all times during the race.

Drivers must stay within their starting lanes for the duration of the lane length.




Width: No more than 1.2m               Length: No more than 3m maximum


Each trolley must have a minimum of three wheels.


Each trolley must have a braking system that:-

• acts on at least two wheels or capable of holding the trolley on a 20 degree slope.

• can be applied in a controlled and progressive manner.

• provide stable and efficient braking without adverse effect on the directional control of the trolley.


 - preferably foot operated braking or steering control (bike brake) mounted braking to avoid driver removing hand/s from steering.



There are hardly any rules for these youngsters as we just want them to have fun and get the racing bug.  After all, these are the trolley enthusiasts of the future.

In the spirit of the event, it is the parents/guardians of the Nippers who decide how many racers for this grade.  Usually it's the parents who want to stop before the kids!

A parents meeting will be held on the day.  Bring along your drivers and trolleys ready to start the racing.  Some Nippers are too young to race all the way so if you want your kids to start from just a few meters above the Finish Line then that is fine.

To operate the brakes you can run behind the trolley holding onto a rope and/or bungee to act as an "anchor".  Make sure you have someone to relieve you as history has taught us that the parents get tired before the kids.

All Nippers participants receive a certificate and badge in recognition of their participation.  It's all about participating so there are no awards for 1st, 2nd or 3rd in the Nippers class.





Due to a few crashes in the 2013 Trolley Derby we have implemented some build requirements to help provide greater safety to the drivers and try and avoid any nasty injuries. Please note that if you are in the Nippers category you do not need to fully comply to these requirements. Nippers start from half way up the course and the trolley must be under control by an adult running behind the trolley holding onto a rope or bungee attached to the trolley.


To check for stability and build strength, trolleys will be placed sideways on a 35 degree ramp with the heaviest driver that will be using it inside. 

A ramp at this angle simulates the forces your trolley will take if you corner at the limit of your grip, and it tests two things:

1.    Trolley stability - your trolley must not tip over.  If your trolley tips over on the ramp you are more likely to flip your trolley instead of skidding if you turn sharply. Skidding is much better than flipping! If you think your trolley might be too top heavy then focus on keeping the driver as low as possible and the wheels far apart. Just remember "low and wide is the way to ride".


2. Build strength - your wheels, axles and frame must not buckle, bend or break when on the ramp.  If your trolley fails this test you run the risk of your cart falling to bits when cornering and probably flipping. If you are using large bike wheels you will probably fail this test because they are not designed to take sideways loads and will buckle very easily - even on straight roads as shown in these videos (Scroll to 53 seconds in the first video):

"The Ramp Test"


The ramp test is now part of scrutineering and your trolley needs to pass this to be allowed to race. It sounds hard to pass but get the basics right and it's a breeze - see this image:

To help you out we will have this ramp set up for you to test your trolley on at the build clinics throughout October. Your trolley will also be tested on this trolley at Scrutineering so we encourage you to bring your trolley down to test it at the build Clinics, or test it on similar slope at home.



Most bike wheels use a 3/8 inch axle however there are some that use a 1/2 inch axle which tend to be much stronger. If using bike wheels it is recommend to have some sort of support on the outside of them to stop them "tucking in" when cornering or under speed.

Spoke strength also effects the strength of the wheel - BMX wheels are designed for a bit more punishment so tend to have stronger spokes/more spokes, and stronger rims. The larger the wheel the more likely it is to buckle if your trolley is very heavy and/or your spokes or axles are weak. The course may be reasonably straight however in the casee of an unforeseen accident you may be required to take "evasive action" and the axles and spokes may not handle the jandle when asked to turn.



If you can want the full monty and can find some wheel chair wheels these are very good as they have a very strong axle that is self supporting, they normally have very good bearings, and strong spokes. These are generally quite large so aren't always the best for acceleration however may give you a higher top speed (not probably relevant on shorter courses like ours.)



All trolleys are required to have a steering system capable of manouvering at a speed.  That is, you are able to avoid a trolley in front of you if it crashes.

Because trolleys with old-fashioned rope steering have proven to be dangerous,

rope steering is NOT permitted.


Steering should be smooth and without excessive free play. You should limit your steering angle to prevent over-steering which is the primary cause of flipping carts. Check out this video for a classic example:


(also notice that the small wheels won the race!).

We also strongly encourage a steering ratio of 1:1 or greater to avoid jerky steering. 

Steering ratio refers to the ratio between the turn of the steering wheel (in degrees) or handlebars and the turn of the wheels (in degrees).

The steering ratio is the ratio of the number of degrees of turn of the steering wheel to the number of degrees the wheel(s) turn as a result. In motorcycles and bicycles, the steering ratio is always 1:1, because the steering wheel is fixed to the front wheel.


A steering ratio of x:y means that a turn of the steering wheel x degree(s) causes the wheel(s) to turn y degree(s).  If one complete turn of the steering wheel, 360 degrees, causes the wheels to turn 24 degrees, the ratio is then 360:24 = 15:1.

A higher steering ratio means that the steering wheel is turned more to get the wheels turning, but it will be easier to turn the steering wheel.

A lower steering ratio means that the steering wheel is turned less to get the wheels turning, but it will be harder to turn the steering wheel. Larger and heavier vehicles will often have a higher steering ratio, which will make the steering wheel easier to turn. If a truck had a low steering ratio, it would be very hard to turn the steering wheel. In normal and lighter cars, the wheels are easier to turn, so the steering ratio doesn't have to be as high. In race cars the ratio is very low, because the vehicle must respond a lot more quickly than in normal cars. The steering wheel is therefore harder to turn.


Roll Bars:

It is recommended that designers and builders try to incorporate a roll bar for the trolley to protect the drivers head.



Trolleys must not weigh more than 45kg.

Trolleys must be the same weight at the finish line as they were at the start line.


Protective Clothing:


Children must have head protection which at a minimum must be a cycle helmet. 

Adults must have head protection which is to be either a motorbike or BMX helmet.


Drivers of open trolleys must have:-

• elbow and knee pads

• enclosed shoes

• long sleeve shirts

• trousers




The trolleys and all drivers must be scrutineered before racing commences and if they pass scrutineering they will receive two stickers, one to be placed on the trolley and one to be placed on the head gear and protective clothing to be worn by the driver during the racing.

For 2017, Scrutineering will occur at the Mangere Bridge Scout Den on the Saturday and Sunday the week before the event - Saturday 1st April, and Sunday 2nd April.

This allows you the opportunity to fix any issues in the week before the event, and then get retested on Race Day. After scruntineering, trolleys can be stored at the Scout den for the week.

If you are from out of town and can only bring your trolley to race day we will be doing scrutineering on Race Day for you, however if your trolley fails and is unable to be bought up to spec then and there, then you will not be able to race.



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