Hello there

[Jo Hill]

Hi, I'm John and I found this place on my searches of the web. I am looking for info and direction on either aquiring or converting to a small wheel electric bicycle. Ideally 16" wheels, and also converting my/our 20" wheel tandem to electric.

I have this idea that throttle alone option is essential, but may be that is erroneous. I just like the idea of being able to just stop pedalling for stretches of time. That is if I understand the whole system correctly.

Input very welcome. Thanks.

 

[Mike63]

I have this idea that throttle alone option is essential

Hi Jo.....how about armchair style padded seat and handlebar mounted TV

....sorry no throttle alone option available.

 

[Deleted member 4366]

You're right about the usefulness of throttle only, but for normal travelling, power from the pedal sensor makes it much more convenient. It's best if you can get a system with several levels of pedal-assist.

Have a look at the threads about converting Bromptons y Jerryimon and others. For the Tandem, the extra power of an Ezee kit would be useful, or you can make your own kit by buying the components from various Chinese suppliers, which is better if you have precise requirements because you can mix and match.

If you give more info about your expected journeys, levels of fitness. etc, it would be easier to advise.

 

[Jo Hill]

Thanks for imput. Hi, I'm not especially fit - anymore - I'm 62. The maximum journey is likely to be about max 20 miles on the dahon but rarely and on the tandem with my partner - she is pretty fit for 53, as long as poss - I guess. I'm fine along the flat but do flag at the hills - to the point of wanting to avoid some journeys. Our tandem is a lovely old Graziella made in the 60/70s, 20 inch wheels quite heavy, 3 speed sturmey archer hub, drum brakes. Oh yes, funds are limited - as I guess for us all. Thanks.

 

[Jo Hill]

A real newbee question. How mix and match are these kits, is there a standard that they all adhere to,

and is it practicable to take say a second hand ebike and shift the system over to a same sized wheel bike.

 

[Deleted member 4366]

The cheapest way od doing a 16" wheel bike is with a Q100 kit from BMSBattery, or the equivalent from Greenbikekit.com. Probably Greenbikekit is better because they do a nice little Panasonic battery that can be fitted in a number of locations. The problem with 16" wheels is that there's more than one size. The Bromptons and Mezzoos have 349mm, and the Chinese ones are 305mm, which means the brakes don't match the rims. 20" folders are much easier.
36V9AH panasonic lithium ion battery for e-bikes-GreenBikeKit online store for electric bicycle components-GreenBikeKit.com
Here's the ki. You have to select 328rpm and 16" wheel size and pay the extra $9 for the LED displlay panel.
GBK-100R 36V250W rear driving electric bike kit for DIY electric bike-GreenBikeKit online store for electric bicycle components-GreenBikeKit.com

 

[Jo Hill]

Thanks so much for the info. Yes indeed, on my old Dahon the back rim is 304 according to my vernier caliper - close enough - give or take. So will the greenbike kit 16" wheel be ok?

Would the 20" greenbike kit do for the tandem?

I notice that you only mentioned the rear wheel option, wouldn't it be an easier job for the front wheel?

Thanks again for you help and guidance.

 

[Deleted member 4366]

Thanks so much for the info. Yes indeed, on my old Dahon the back rim is 304 according to my vernier caliper - close enough - give or take. So will the greenbike kit 16" wheel be ok?

Would the 20" greenbike kit do for the tandem?

I notice that you only mentioned the rear wheel option, wouldn't it be an easier job for the front wheel?

Thanks again for you help and guidance.

Looks like the Greenbikekit will be good for your Dahon.

For the tandem you need a front motor because you have a Sturmey Archer hub at the back (?). You need to check the distance between your fork drop-outs. Standard is 100mm - the same as the motor, but some small-wheeled bikes are narrower. This motor gives a bit more torque:
Bafang SWXK5 e bike conversion kit 36V250W front driving 8fun ebike kit-GreenBikeKit online store for electric bicycle components-GreenBikeKit.com
You could get the same Panasonic battery for convenience, or get this one from BMSBattery, which fits easily to the rack. You''ll need to get some 12g or 14g silicone wire to extend the lead to where you mount the controller, which would be round about the front seating position:
36V15Ah Li-Ion Alloy 05-Case EBike Battery Pack - BMSBATTERY
You'll need some sort oof box to mount the controller in. Both these companies sell the same box, but it''s a really tight squeeze to get everything in unless you can eliminate some of the large unnecessary connectors by soldering the wires together. These kits are not 100% plug-and-play. You sometimes need to swap pins on the connectors and check everything carefully. You need to be able to do basic wiring and soldering.

 

[Jo Hill]

Thanks again so much, I will study your suggestions in a moment, but just to clarify, I also have a sturmey archer 3 speed on the dahon as well as the tandem, so I guess you would suggest the front wheel option there too? I am assuming that the front is the same as the back, but I can go measure in a minute or two. Thanks, J.

 

[jhruk]

Thanks so much for the info. Yes indeed, on my old Dahon the back rim is 304 according to my vernier caliper - close enough - give or take. So will the greenbike kit 16" wheel be ok?

Would the 20" greenbike kit do for the tandem?

I notice that you only mentioned the rear wheel option, wouldn't it be an easier job for the front wheel?

Thanks again for you help and guidance.

Make sure you check the exact rim size of your 20” tandem as well. There are many varieties of 20” but you’re likely to get a 406 if you specify 20” from BMS or Greenbike. I have a 20” Dawes that’s 440. If your wheels are not 406 you can just order the motor and build your own wheel.

If you prefer front wheel drive on the Dahon, and it has narrow forks, you might be interested in the Q85, which has an 83mm width non disc version. An excellent little motor very similar to the Q100.

 

[Jo Hill]

Total apologies, my measurements were all to pot. on the dahon, front and back are more like 3.3 -3.4 cm. As you can tell I'm new at this. I think I'm reasonably handy, but soldering - I have never done that, though I understand the rudiments of lekky. Still getting used to thes calipers, not used to 10th of a mm level of accuracy.

 

[Jo Hill]

Thanks, the q85 looks good. I will leave the tandem for later, build a bit of skill and confidence with the Dahon. It is a lovely old Dahon, a joy to ride, I have put on Brompton m type handlbars which give an extra few inches in height overall which is fantastic. Another question, which might sound really daft, but, I was wondering why the wheel width was sooooo important given, as is the case with my old Dahon, there is a level of give in the brake setup, because of the ancient brake system, so with an old single speed 16" one I was given to restore, which I did. I realise of course that the wheel has to be thin enough to go between the forks.

 

[jhruk]

Thanks, the q85 looks good. I will leave the tandem for later, build a bit of skill and confidence with the Dahon. It is a lovely old Dahon, a joy to ride, I have put on Brompton m type handlbars which give an extra few inches in height overall which is fantastic. Another question, which might sound really daft, but, I was wondering why the wheel width was sooooo important given, as is the case with my old Dahon, there is a level of give in the brake setup, because of the ancient brake system, so with an old single speed 16" one I was given to restore, which I did. I realise of course that the wheel has to be thin enough to go between the forks.

Hi Jo, d8veh and I were referring to the diameter of the rim, not its width. As you may know nominal values of 16” and 20” can refer to many different actual rim diameters - Sheldon Brown covers this topic quite well here. It’s usually marked on the side of the tyre so probably no need to measure it. Of course this is only relevant if you wanted to order a ready built wheel, if you just order the motor you can build it, or have it built, into any size rim.


If you’re fitting these to the front wheels you may find you need to spread the forks a little, even if the axle width seems ok. I fitted a Q85 to a 20” (406) Dahon and it fitted perfectly, but fork/motor clearances were very tight. They might be even tighter on a 16”. You can see the Q series motor dimensions here. Plenty of threads on the forum about fork spreading.

 

[Deleted member 4366]

The problem with the wheel size is not the width.. It''s the diameter. If you put a 305mm wheel in a 349mm bike, the brakes will be clamping on the tyre instead of the rim.

You'll have to use a front motor in the Dahon. You have to take the front wheel off and check the with where the axle goes to see if the motor will fit between the forks.

 

[Jo Hill]

Thanks so much for your patience, so sorry, I utterly got hold of the wrong end of the stick, I can't quite explain why, but how I could turn in my mind 3-- mm into 3.-- cm - doh! I think I am finally getting the picture now. Thanks for the info about the forks, yes indeed a big hub motor will need definate clearance. It's late now, I will do some more wheel measurements tomorrow in day light, and hopefully less tired and confused. Thanks again.

 

[Jo Hill]

Hi again, well - another day, I had a looks at Sheldon's page, complicated stuff - this rim sizes thing. I do notice that I have a good bit of room to manauver with my brake blocks both larger and smaller than my existing wheel. My own measurments are very inconclusive as they seem not near 305 or 349 on the Dahon, the tyres are labelled though 16 x 1.75. However, I think there may be a real problem with the fork, given the limitation of trying to measure it with the wheel in, it appears at the end to be between 60 and 70 mm, notwithstanding that the forks get thicker and therfore even narrower as the go up.

Comments welcome.

 

[jhruk]

A 16 x 1.75 Inch tyre will be 47-305 so the rim should be the same size as get in a 16” wheel kit from BMS battery, so that’s ok.

You can measure the dropout width better by removing the wheel, it’s the distance between the slots. If it’s under 83mm you’ll have to bend them apart and, as you say, you may have to bend them more than the difference to accommodate the motor width further up. Here is a picture showing the tight clearance on mine, fitted without bending. I’m afraid I’ve little experience of fork spreading, but you’ll find a lot of useful info. by searching the forum - Brompton threads may be useful.

 

[Jo Hill]

Thanks for info and picture.