Hello! I upload the post here because I did not find another group that fit the issue better.
I have a week with some doubts about a project that I would like to do and if someone could solve them I would be great.

What I thought was to remove the 2 wheels from the middle of a inline skate like the one in the photo and put in that spot a battery and the engine inside the wheel (cutting the spikes off to fit in).

I also thought that the motor could be like in the photo. Thin but with a large diameter so that the boot frame could be mounted on the shaft and the outside of the engine is what moves the wheel, like the engine of a skateboard.
What would your opinion be? Could it be viable?
Thank you!
how about you motorize the front wheel? that way you won't have the motor engage while you use the brake (which is the block hanging off the rear wheel, I assume?).
strap the battery to the outside of the skates, to be less restricted with the size of the battery and to have one more wheel, increasing the contact area between wheels and ground.
when you motorize the front wheel, you could look into motors that allow the center to stay fixed in place and the outside to spin to put the motor into the wheel, otherwise you can put it in line in front of the wheel with a guard around it, granting you more freedom to position it, a potential gearing up or down if you want and also enough space below for all the wheels to remain, reducing the amount of necessary modifications to the base product.
I don't inline skate, so I'm not sure how easy these ideas are to implement, you'll have to figure that out yourself.
Thanks for your answer.
Yeah the plan is to motorize the front wheel but I have 2 big issues with that:
First is to find that kind of motor that will spin the outside.
And second which is the one that most concern me is that the motor will not be able to stand my body wheigth and the shaft will bend or even break.
Is more easy for me to get out the center wheels and I prefer to motorize the wheel rather than have the motor outside connected with some belt or gear, I see it more elegant.
you need to check the 'shaft side load' rating of that motor and make sure it can hole the weight of a human pushing down on the skate wheels I dont think you will find a motor that size with a large enough side load capacity.
Also you need to check the 'motor torque' rating for the motor you are using to make sure this motor is actually capable of pushing a human along and is able to accelerate that person to the speed you want in a reasonable amount of time.
Also you need to check the rated 'motor speed' most electric motors like to spin at speeds much faster than a skate wheel.
You would be better off mounting a motor somewhere else on the skate and using a chain & sprocket system to gain the speed reduction & torque increase you need and that way all your weight can be supported by whatever axle the skate has and not by the motor.
Also you need to consider battery size. Any kind of set up like that is going to put a large drain on the battery and if you want to be able to operate this for a long time you will need a larger battery which will also need to be mounted somewhere else.
Also have you thought about what kind of control system you want to use? you dont want to just turn the motor on and have it run full speed all the time, you will need some way to regulate the speed of the motor.
You might check with ACME company I believe they have done some work in this area.