Yes, we can put a kit together for your beach wagon. If it will be used in the sand then both of the back wheels should be connected to a live axle so it has 2-wheel drive. When we first started making beach wagon kits some of our customers made 1-wheel drive beach wagons and they all just spun their wheels in the sand and did not go anywhere, so 2-wheel drive is needed for wagons that are used in the sand.
So we can start designing the kit; how much weight will the wagon need to carry? And how many minutes of runtime will it need to have?
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We carry live axles, bearing hangers, wheel hubs, etc. for beach wagons however these are new parts which are not listed on our site yet. We could add them to a kit though.
We have freewheels that work with our sprockets and axles so that is no problem at all.
All of our throttles and brake levers fit onto 7/8" OD tubing or handlebars and are designed to slide onto handlebars with ends and they are not designed to mount to round handles. Due to this a handlebar with ends may need to be attached to the round pull handle so the throttle and brake lever can be mounted.
We have not received any reports from our customers of one wheel drive beach wagons working in the sand although that may be without the addition of human power to the wagon so we are not sure if one wheel drive will work if you help it to get started.
For a beach wagon with a 300-pound gross weight a 600, 650, or 1000 Watt motor will do the job with a 3-4 MPG top speed.
The battery life is only limited by how much space and weight capacity the wagon has for the batteries. If you go with a 45-minute runtime then the battery pack will be fairly small and weigh around 25 pounds, once you get into the 1.5-hour, 2-hour, 3-hour, and 4-hour runtimes the battery pack gets incrementally larger and heavier depending on how much runtime the wagon is designed to have.
Please let us know your thoughts and we can take it from there.
We have an SPR-B1211FW freewheel sprocket that fits onto our MOT-24450G 24V 450W motor. This freewheel sprocket is for 1/2" x 1/8" (#410) bicycle chain.
I ran a gear ratio calculation and found that with the sprocket and motor listed above and a 13" diameter wheel, a 48 tooth sprocket would be good for a top speed of 4 MPH. If you want it geared lower than that then a larger wheel sprocket would be needed. A 65 tooth sprocket would provide a 3 MPH top speed.
We can check and see if a wheel sprocket is available that fits your wheel if you could let us know the number of teeth, bolt circle diameter, bolt hole diameter, and minimum center hole diameter for the sprocket. Or we could include with the kit any sprocket on our site that you deem to be suitable for the job.
As far as a brake kit goes we would need to find a rotor that would mount on the wheel so once we know the sprocket mounting specifications then we can look further into that.
That 24V 450W motor only has one type of mount, however, we have a mounting bracket for it (item # HDW-250) that is designed for a bicycle and is steel so it can be bent, drilled, and/or welded for mounting the motor to other applications.
HDW-250 Mounting Bracket
I checked and there are no already made sprockets available for a bolt circle diameter with three holes that are 3" apart as shown in your photo, so that sprocket would need to be custom made. I checked with Rebel Gears today and they said that they can custom make the sprocket for #410 chain. You can order the sprocket directly from them. I recommend purchasing or borrowing a digital caliper before ordering so your measurements are precise because their custom-made sprockets are not returnable.
Here is a link to a calculator for determining the bolt circle diameter from measuring the center to center distance between two adjacent bolt holes: https://littlemachineshop.com/mobile/bolt_circle_dia.php
There are no brake rotors available that fit the rim bolt pattern either so a plate adapter with holes would need to be made to convert the rim pattern to a standard brake rotor pattern. We could include a brake kit with a standard rotor and then you could make or have made the adapter.