Etandem 1st self build

[harleynice1]

Hi, Iam a newbie my wife and I ride a tandem and have recently completed our 1st E’tandem conversion. we’re both somewhat retro in both our years and our bike.
It is a Dawes Galaxy which was a double gents but I had it converted to ladyback ( wife has new hip joints) by a brilliant frame builder it Lewisham London -photo attached ) .The motor is a Bafang 500w rear hub motor but needs a better controller as ours gets very hot .the battery I intend to have it adapted to 2x batteries instead of one and have them positioned in the rear pannier bags .
im thinking of changing the current set up with a more powerful front 750W motor as to help with better weight distribution and give more torque ,we’re looking for help and advise in all aspects of ebiking and will look forward to learning more that will help us with our rides.

 

[m@Robertson]

That looks like a really neat frame.

A front motor is a great thing with respect to the now-2wd nature of your propulsion, but it will be a bad choice for a tandem. The reason is all of the motor's torque will be pulling a load consisting of the weight of two people plus the bike, and you will be putting all of the stress of that motor on your headset bearings and more importantly, your fork and fork dropouts.

A front fork can and should have two torque arms attached to minimize the danger to the dropouts - and they can be completely effective - but nothing is going to reduce the severe strain on the fork and headset. No headset or set of fork blades were made to be pulled upon. Now, they can do it but its a strain, and its a lot more of a strain when the motor is pulling two people. Can you do this successfully? Maybe you can, but there are definitely better choices.

One of them is to use a mid-drive instead of the hub motor. That will let you use the drivetrain and the gears.

But a simpler option - and one you've already gotten halfway to already - is to put in a second hub motor in the front to supplement (not replace) the rear.

That will create a powered 2wd bike, and you will be amazed at how effective it is. Especially if you are not in particularly hilly country. 2wd hub bikes excel in flat land and low rolling hills. Not so good for steeper hills.

Some food for thought on the 2wd subject:

Dual Motor AWD Electric Bikes (the good and bad)

I like to build top-quality-component ebikes from the frame up. Quite a few of them are dual motor or AWD or 2WD or whatever you want to call them. Why would you build an AWD ebike?

talesontwowheels.com

There is a slew of stuff at that site (which is mine) on helping out newbie builders.

How To Build An Ebike From Scratch

You want to build an ebike, but the project seems overwhelming. Lets de-mystify the entire process, including planning, parts and perfecting the end result.

talesontwowheels.com

 

[Smaug]

Welcome, from SE Wisconsin, and good luck with your 750 W conversion and finding the right controller.

 

[m@Robertson]

Welcome, from SE Wisconsin, and good luck with your 750 W conversion and finding the right controller.

For a geared hub motor, a 500w/48v/45Nm with a KT controller that has simulated torque assist is probably as big as you can get. To go bigger I think you'd need to go to a direct-drive hub, which would have no moving parts but would also be really heavy and have less torque output. The only front hubs I know of in common use at 750w are the fat Bafang G06x motors and they're not going to fit this bike.

When shopping hubs, try to ignore the wattage rating. Its only a measure of how much raw current a motor can absorb (over an unpublished amount of time) without damage. The better measure of motor performance is the torque output. It will be a measure in Newton Meters. realistically you can ignore everything else as only the pull the motor gives you will be what you appreciate as a material difference. Voltage and wattage will take care of themselves as the higher/more acceptable torque output motors will just naturally be 48v and higher wattage-rated.

 

[ElHegpah]

Can't see your controller in the picture, but if it is in one of those bags, get it out into the airflow. Controllers need cooling airflow.

Strongly recommend against a front motor on that bike, reasons summarized above. Also strongly recommend against any sort of battery blender or combiner, these devices are, for the most part, seriously unsafe.

Maybe upgrade to a 750, or 1000 watt, rear hub.