converting old shopper bike (Puch Promenade)

[Kareny]

Hi, I have a beloved Puch Promenade (basically a Raleigh 20) that I have neglected for too long and want to convert to an e-bike at the same time as restoring it. I am looking for a bit of advice on kits (I want to do it myself rather than take to a shop but open to paying a bike shop/mechanic for some expert advice if needed). Basically I cant do a front wheel conversion as it has 80mm forks and 20" wheels so doesn't fit either brompton or standard wheel kits. I am thinking mid drive is the way to go here, but concerned about a couple of things and looking for advice please.

- As it is a sturmey archer gear system I am guessing it will essentially become a fixie when i convert it, will this make it considerably harder to pedal? I know the torque on mid drive kits is done with the bike's gears.
- probably being thick here but where does the motor actually fit? do i need a certain width of ground and pedal clearance (I'm assuming they would mention this if so...)
- has anyone used the cyclotricity mid drive conversion kit? its looking like the best option to me as it can come with pannier rack battery and they seem fairly well made but as they are slightly pricey and I don't need the 500W mode if anyone has suggestions I'm all ears - i do need to be able to use a removable pannier rack battery though.

Has anyone converted a bike like this before and have any tips?!
thanks
Kareny

 

[vfr400]

I've converted exactly that bike before. It was very straight forward. I can't remember whether I used a Q85 or Q100 motor, though I think it was the Q100 and I spread the forks to fit it. A Q85 is identical apart from the width (85mm vs 100mm). I used an old laptop charger box for the controller, fixed to the frame either a couple of stainless strips as U-brackets. Any rack battery would work. Ideally, you want one that fits to a plate, which you bolt to the existing rack. I recommend a KT controller with any of their LCDs. I kept the original braks and used an inline brake sensor (AKA Hidden Wire Brake Sensor).

You can get all the parts from BMSBattery.com.

There's one problem you might have, which was no problem for me. There are two 20" wheel sizes. The Chinese 20" ( 406mm) is much smaller than these old 20" ones (451mm) , so you have to buy just the motor and lace it to the rim yourself. Look at your tyre and see what numbers are written on it for the metric size next to where it says 20" x 1 3/8 or whatever it is. You won't find any kit that has a 451mm wheel.

You need to make sure that you tick 328 rpm on the motor.

Q85 36V200W-250W Front Driving V-Brake Hub Motor RPM 328

Q85 36V 200W-250W Front Driving V-brake, rim-brake E-Bike Hub Motor. Waterproof Hall Sensor and Sensorless compatible plug.

bmsbattery.com

S06S 250Watts Torque Simulation Sine Wave Controller

S06S 250Watts Torque Simulation Sine Wave Controller for 24Volts or 36Volts battery pack E-Bike System

bmsbattery.com

S-LCD5 LCD Meter for S-Series Controlers Color Black

S-LCD5 E-Bike LCD Meter for S Series Controllers.

bmsbattery.com

Eight poles PAS--Pulse Padel Assistant Sensor

Eight poles PAS--Pulse Padel Assistant Sensor for Electric Bicycle. 1. RED --- +5V ; 2. GREEN --- Signal; 3. BLACK --- GND. Connector: SM-3A

bmsbattery.com

Speed Sensor

Speed Sensor

bmsbattery.com

HWBS - Hidden Wire Brake Sensor 1pcs

HWBS (Hidden Wire Brake Sensor), Wire Length: 1.2M

bmsbattery.com

New Thumb Level Throttle without handle Throttle Right

New Thumb Level Throttle without handle

bmsbattery.com

This battery includes everything you need except the motor, i.e Controller, PAS, throttle LCD etc are included. The rack might be too high for a 20", so I'd just get the battery with the included controller, and fit the mounting strip to your rack. You'll have to make some brackets for that.

36V12.5Ah/14.5Ah/17.5Ah Case-02 Battery Pack Cells / Capacity 2.5AH High C-Rate / 12.5AH Inner Controller With Rack Without

Case-02 ebike Panasonic battery pack 36V14.5Ah included a charger. there is an output for ipad and cellphone charging. A 18A sine wave controller inside.

bmsbattery.com

Before.


Forks before and after. It's a Q100.



Battery mount. It looks a right mess at this stage compared with how it turned out. I rebuilt the back wheel to match the front one. IIRC a Sun CR18 451mm rim. That's it by the wall.

 

[Kareny]

Wow thanks! That’s amazing, I’ll have a look at all the links. Do you reckon a front hub is definitely a better shout than a mid drive then? I was concerned about stretching the forks on such an old bike to be honest. This is my bike so pretty similar.

 

[vfr400]

It's OK to stretch steel forks. Age doesn't matter. You can now get the Q70, which wasn't available when I converted mine. You don't have to stretch the forks with one of those. I think a front hub-motor will be a lot better than a crank-motor.

 

[Amoto65]

Loving the Raleigh 20 conversion, I have 4 Raleigh 20s at the moment and am seriously considering a conversion like that, regarding the Puch they have the smaller 20" (406) wheels.

 

[Kareny]

Loving the Raleigh 20 conversion, I have 4 Raleigh 20s at the moment and am seriously considering a conversion like that, regarding the Puch they have the smaller 20" (406) wheels.

thanks, I was getting confused as the tyres say 451 but when I measure the wheel diameter it is definitely 406, they are the tyres on it when bought 11 years ago so I didn’t fit them, I’m guessing the person who did bought the more common size
does that mean I could theoretically use a 20 inch wheel kit if I stretch the forks? building a wheel is a bit daunting without the proper kit for trueing it!

 

[vfr400]

If I did it again, I think I'd use a downtube battery on the crossbar. You'd have to add two or three rivnuts to the tube to hold it. That would leave your rack free for anything you want.

A warning about the rack. The one I did was broken before I started. The welds on the frame bracket at the front had detached, so I repaired it and added a couple of extra supports attached to the seat tube clamp. I don't know why the welds detached. Maybe they were badly done, but with the weight of a battery bouncing up and down on them, it won't be any better.





I'm now thinking that this battery with the included controller/LCD kit might be a better option. All you need in addition is two or three 5mm rivnuts, a Q70 motor, a Sun CR18 rim and spokes to suit. They don't say how powerful the controller is, though it should be written on the label. whatever it is, I'd set the currrent down to 12A in the C5 setting. C5=6 divides the current by 1.25, so it would be the setting if it's a 15A controller.

36V12.5AH/14.5AH/17.5AH Case-08 Bottle Battery Pack Cells / Capacity 2.5AH High C-Rate / 12.5AH Inner Controller With

New design bottle-08 ebike panasonic NCR18650PF battery pack 36V14.5Ah included a S180 charger. there is an output for ipad and cellphone charging....

bmsbattery.com

 

[vfr400]

thanks, I was getting confused as the tyres say 451 but when I measure the wheel diameter it is definitely 406, they are the tyres on it when bought 11 years ago so I didn’t fit them, I’m guessing the person who did bought the more common size
does that mean I could theoretically use a 20 inch wheel kit if I stretch the forks? building a wheel is a bit daunting without the proper kit for trueing it!

If the tyre says 451, that's what you have. Are you sure that you're measuring correctly? You measure across the diagonal from and to where the bead of the tyre sits on the rim. You have to use a bit of judgement where that is.

 

[Amoto65]

I had a Puch Pic-nic folder earlier in the year and that had the 406 tyres on it, as far as I know only the Raleigh 20s and its various incarnations had the larger 451 rims fitted which are nearly 2" bigger than the Puch wheels.

 

[Kareny]

If the tyre says 451, that's what you have. Are you sure that you're measuring correctly? You measure across the diagonal from and to where the bead of the tyre sits on the rim. You have to use a bit of judgement where that is.

If the tyre says 451, that's what you have. Are you sure that you're measuring correctly? You measure across the diagonal from and to where the bead of the tyre sits on the rim. You have to use a bit of judgement where that is.

I’ve measured again and you’re right - it’s a 451! so i spoke to cyclotricity and their front wheel kit is 451, obviously they told me not to stretch the forks but i understand they have to say that! So I think I will start taking it apart and see if stretching is viable, if not I’ll have to look at swapping out the forks as a complete wheel build is beyond me as I live in a very small flat and don’t have the tools so would cost more in the end.

 

[Amoto65]

I agree if the tyre says 451 that is what it is, the same as vfr 400 says, I am just a bit surprised. Either way I look forward to seeing the conversion which I hope you will detail.

 

[Amoto65]

It appears the Puch Pic-nic had the smaller 406 wheels due to it being a folder.

 

[vfr400]

I’ve measured again and you’re right - it’s a 451! so i spoke to cyclotricity and their front wheel kit is 451, obviously they told me not to stretch the forks but i understand they have to say that! So I think I will start taking it apart and see if stretching is viable, if not I’ll have to look at swapping out the forks as a complete wheel build is beyond me as I live in a very small flat and don’t have the tools so would cost more in the end.

I'd double check with Cyclotricity. 451mm rims are very hard to get these days. They're nearly all 406mm. Have a look on Ebay or anywhere else to see if you can find one in the UK that isn't 406!