Weight limit of hub motor for tandem

[Gloop]

I'm converting a single speed tandem to a dual motor touring bicycle.

This is the bike.

Loading…

www.actamid.com

In the front im putting my old 1000 watt crystallyte 48 Volt motor.

In the back I want to put this motor...it is mainly a backup and for hills since there are a lot of hills in British Columbia.

Loading…

www.amazon.ca

I have two questions.

Is it possible to mount a single speed casette on a multi casette axle? Will i have to use a lot of washers to make up for empty space?

And the amazon link says weight limit is 220 lbs. With two riders and batteries, the weight is going to be about 450 lbs. Should I buy a motor with thicker spokes?

My other option is to spend a little more and get a better motor from ebikes.ca

 

[RunForTheHills]

Wow! A folding single speed tandem BSO. Wheels built for tandems usually use stronger rims as well as more spokes. It is not just the thickness of the spokes that give it strength and a thicker spoke can actually break a weak rim at the right tension for that spoke. If you get a better motor from Grin, they can build it into an appropriate rim for you. You can buy an adapter for a single speed cog. It is still going to look like you used a lot of spacers.

 

[E-HP]

Is it possible to mount a single speed casette on a multi casette axle? Will i have to use a lot of washers to make up for empty space?

Are you sure it’s a cassette? From the pics it looks like a freewheel (which may be better in your case).

 

[gromike]

I would be more worried about that bike when going down hill fully loaded. You sometimes pay a much higher price when you electrify a cheap bike.

 

[amberwolf]

In the back I want to put this motor...it is mainly a backup and for hills since there are a lot of hills in British Columbia.

I recommend going to ebikes.ca and using their simulator to see how much power it actually takes for your specific riding conditions. Then you can better guesstimate how big a motor and controller you need, and use the wh/mile figures to guesstimate how big a battery you will need to run it for the range you require.

Is it possible to mount a single speed casette on a multi casette axle? Will i have to use a lot of washers to make up for empty space?

How exactly you mount it and space it out depends on the actual cassette (or freewheel), as well as the sprocket, freewheel, or cassette you choose. Not knowing which one you're going to use and how it fits in your chainline I couldn't give you any specifics.

But: do you really want to sacrifice your ability to shift pedal gears, for the event of motor system failure for whatever reason? The bike is a singlespeed now, but you could upgrade it with a derailer and shifter for the rear.

And the amazon link says weight limit is 220 lbs. With two riders and batteries, the weight is going to be about 450 lbs. Should I buy a motor with thicker spokes?

No. If you need a better wheel, thicker spokes by themselves isn't the answer, as that makes a weaker wheel if the rim (and spoke flanges on the hub) aren't designed for the higher tension. The typical 12g spokes hubmotors are built with are problematic because they don't usually use rims capable of handling that higher tension (and they're not usually very good spokes, either). For my heavy heavy-cargo trike SB Cruiser, I use Sapim 13/14 butted spokes on the rear weight-carrying wheels, and 15g on the front. 15 would probably work on the back too, but Grin didn't have that small a size when i ordered way back when I built the wheels.

Are you going to have 450lbs on that one wheel? What a wheel handles in weight is just what portion of the total weight is on that wheel, out of however much total weight and however many total wheels there are.

 

[PaPaSteve]

Sure looks like a thread-on freewheel on that rear hub motor.
Simply put the chain on any of the cogs that provides a suitable chain line and gear ratio.
but
Motor wheel as provided will be on the edge of weight rating.

 

[DaLanMan]

well in the specs list on amazon it has a weight limit listed...

Weight Capacity

220 Lbs (100kg)

So, I could ride with that unit, if my bike weighed like negative 10 pounds...

Ok, if it was a unicycle,

The simple process:

Veh weight,
+
weight of passengers and addenda
needs to be =< 47% of half the max load. Unless you feel the manufacturer included the event of oh, going off a 20cm curb, in which distance you will come real close to a double weight impact, and it is gonna hit each tire at double value (so if you have 200 pounds total weight including passengers, their water bottle, motor, batts etc, each tire is carrying 100 pounds, and on a step drop impact is not terribly horrible, but add the forward momentum giving you multiple vectors of stress and you can load that up to 200-300 pounds real quick.

All the things you learn in Jump school...