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Mobility scooter build questions

I am designing a lightweight, takedown mobility scooter. One question I have is on motor wattage. I am trying to keep the scooter weight to under 100 pounds and i weight about 250 pounds, so total weight would come in at about 350 to 400 pounds. I am planning for a very short wheelbase, so a top speed of 7 or 10 mph is all I should plan on. Do you have a recommendation on the wattage and type of motor i should consider? I also want 10 inch wheels with 3.5 inch width to make it easier to navigate on grass and dirt. I pkan on a single drive wheel in back and two steerable wheels in front. I see drive wheels on your website that would work nicely that have a freewheeling sprocket. My question is on the freewheeling sprocket. I need a parking brake for the scooter. Do you have suggestions for how to implement a parking brake? So, my two questions are what motor type and size should i cansider and how can i implement a parking brake?
The Watts rating of the motor that should be used depends on if the scooter will be used exclusively on flat surfaces or if it will need to be able to go up inclines. To be able to go up 20% grade inclines with a gear ratio providing a 10 MPG top speed, a 500 Watt motor should be fine. If it needs to go up steeper inclines then a larger motor should be used. There is no harm in using a larger motor (750-1000 Watts) to start with because you never know when you may need the extra power and wish that you had it.

With 10" wheels you could use a standard motor without gear reduction that has an 11 tooth sprocket and an 80 tooth wheel sprocket attached to a freewheel. Here is the calculation for this setup.

For the parking brake you could install a standard brake that is used while riding, such as a disk brake, and then use a brake lever with a parking brake as shown below.

We currently do not carry brake levers with parking brakes but they are available at many bicycle parts stores. We do plan to carry them in the near future though.

Please let me know if you have any further questions.

Thanks! That's a big help. I did think of one more question. It would be very handy to have a reverse gear capability on a scooter. Is there a way to lock the freewheel sprocket to keep it from freewheeling so that I can reverse the motor polarity and back up?

The freewheel could be locked by welding its stationary and freewheeling parts together, but this would not work because the freewheel is threaded onto the rim and if it was used in reverse it would unthread from the rim and no longer be attached.

A sprocket that bolts directly onto the rim would need to be used for a scooter that has reverse. Here is an example of a rim and sprocket that bolt directly to each other.

Please let me know if you have any further questions.

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