Tongxin Nano Brompton Conversion kits for sale on Ebay!

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
He should really sort it out or make it clear in the listing that the rim is the incorrect size and that it will not suit a Brompton/Dahon with 349 rims.
The seller has offered a £20 refund which I'll take as it's better than nothing, I don't want to send the kit back. As you said Jerry, it's a 28h which helps loads. He was still of the opinion that the 305mm rim would work. I've sent him a picture of the 305mm rim sitting inside of the 349mm for comparison.

16" Rim size comparison | Flickr - Photo Sharing!

James
 

jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
Exactly what I tried to tell him. The front wheel would be dropped lower than the rear wheel!

Thanks for the pic (I hope you don't mind that I cut and pasted it) as I have never seen them side by side like that before

305rim.jpg


The £20 refund will at least fund your replacement rim :p

Brompton 16 x 1 3/8" wheel rim (ETRTO 349), 28H

Though looks like you already have one so will fund some cut to size spokes from catsnapper (Alan). Do you want me to dig out my measurement of spokes so you can compare them with your calculation ? I assume you want to use radial ?

Regards

Jerry
 
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superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
Exactly what I tried to tell him. The front wheel would be dropped lower than the rear wheel!

Thanks for the pic (I hope you don't mind that I cut and pasted it) as I have never seen them side by side like that before

Though looks like you already have one so will fund some cut to size spokes from catsnapper (Alan). Do you want me to dig out my measurement of spokes so you can compare them with your calculation ? I assume you want to use radial ?
Thanks I didn't realise you can cut and paste onto the page.

I'm struggling with the measurements. The flange diameter I've measured at 109mm.
I can measure the distance inbetween the flanges easily enough but how do you measure where the hub centre is? Is it the other measurement I've marked on the pic below? I haven't got a vernier caliper so I think I need to get one.

Tongxin Flange Distance.jpgTongxin Flange Diameter.jpg
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
Forgot to say that yes I was going to go for radial build on this one.

The seller has also asked the manufacturer to build the motor into 349mm rims to which they have agreed. He should be receiving them late February/early March.

I also mentioned about the bottle battery looking a bit big for a Brompton build. His reply was that he could provide a 36V 6Ah shrink wrap battery. His supplier has also suggested another battery type. See the pic below:

new36vbattery_zps3b472b63.jpg

What do we think?

If it's to be mounted on the seat post then I think Shemozzle999's frogpack set up is better as it's not as tall for putting the seatpost down and it takes the controller. Where else could it go? I suppose if you didn't have any front luggage you could make an adapter to put it on the front luggage block. It would be a shame to not be able to carry any other kit though? On the back to the of handlebar stem it would interfere with the cables and on the frame it would interfere with pedalling or being to step through comfortably.

James
 

jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
I'm struggling with the measurements. The flange diameter I've measured at 109mm.
I can measure the distance inbetween the flanges easily enough but how do you measure where the hub centre is? Is it the other measurement I've marked on the pic below? I haven't got a vernier caliper so I think I need to get one.
You only need to worry about the hub if it is not symmetrical as shown on the wheel pro help. So as your flanges are symmetrical between the axle nut faces distances on both sides C & D are 37mm/2 :)

i.e. 18.5mm though measuring with my calipers I get 37.5mm so use 18.75mm. Also i measure 108mm between flange hole centers which are the same both sides A & B.

You then need the actual rim diameter which you can get by following the instructions here

I have measured the stock Brompton 28/36h rim several times and constantly get 338mm. Note this shows you how you can't rely on and use the manufacturers published ERD specs i.e. in this case 349!

So we have

A = 108
B = 108
C = 18.75
D = 18.75
Rim Diam = 338mm
Spokes 28

Putting that into the wheel pro calc I get spoke lengths as

R = 115mm
1x = 122.6 (one cross)

Using your measurement I get R = 114.5 so there really is nothing in it plus I always find the wheelpro calculates a little short for smaller wheels, so I would add at least 1mm longer anyway

So we have

Radial = 116mm
1X = 124mm

I have only built your hub into a Brompton stock 36h rim (I got blank ones drilled for 36h as I only had 36h Tongxins) but the calculation works out the same for radial in both cases. Suggest you double check yourself for your own peace of mind :)

Finally depending on how deep the counter sinks on the flange holes are you may need to use washers alternate holes or you will see daylight through them, though looking at the original wheel I think they did not use them you you will probably get away with doing it without. Radial on small wheels is by far my favorite but I am not sure I would have been confident using it for my first build. My first few builds were all x1 (1 cross).

Re the washers I had to do it on the smaller Goldant motor I fitted into a 20" rim as the countersinks were really deep alternate holes.



Regards

Jerry
 
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shemozzle999

Esteemed Pedelecer
Sep 28, 2009
2,826
686
Hi James,

I did look at that battery - it slides off from the side - the dimensions are detailed here:

http://cnebikes.en.alibaba.com/product/494481088-212862823/36v7ah_lithium_battery_for_electric_bicycle.html

Depending on the saddle, the retaining block would have to be clamped 100mm below the saddle base which means the seat post could not be retracted down far enough for the frame to lock up when being carried.

For the frog type battery you need the extended seatpost.

It might be small enough for mounting on the upper frame tube or even on between the M type handle bars if you fit the special strengthening bar.

Good luck with your build - if you need to borrow any special tools for the conversion send me a PM.
 
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jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
I also mentioned about the bottle battery looking a bit big for a Brompton build. His reply was that he could provide a 36V 6Ah shrink wrap battery.
I am not a fan of battery/controller mounted on portable bikes and tend to use the front pockets of the C bag for battery and controller and then use an umbilical chord from the bike to the controller. If it were my choice I would go for a 36v/6A shrink wrap or a larger battery in the main bag itself.





These are the batteries I use depending on my distance to travel. The largest blue shrink wrap one on the left is a 36v6Ah one that still fits in the back pocket as well. This then keeps the main bag empty and of course spreads the bike weight when carrying bag in one hand and bike in the other.



My first Brompton build/setup is all detailed in my build thread here. If you read through the posts (there is a lot of them!) you will see how I developed and built the system of keeping bike/bag separate connecting with an umbilical chord.
 
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superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
So we have

A = 108
B = 108
C = 18.75
D = 18.75
Rim Diam = 338mm
Spokes 28

Putting that into the wheel pro calc I get spoke lengths as

R = 115mm
1x = 122.6 (one cross)

I always find wheel pro a calculates a little short for small wheels so I would add 1mm or so

So Radial = 116mm
1X = 124mm
Thanks Jerry. That's helped loads. I wasn't sure as there is some asymmetry to the motor.
I notice daniel.weck got 108mm too on his build same as you so think I'll go for that distance.

I've measured the rim using the spokes through the holes and ruler and got 338mm too.

Brompton ERD.jpg

So yep I'm with you Radial = 115 + 1mm extra = 116mm
1x Pattern = 123mm + 1mm = 124mm

Great. I need to go email Catsnapper for some spokes and see if he'll oblige.

Cheers

James
 

jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
If one or two spokes do poke through you can always dremel the heads down a little :eek:

Dont tell Alan though as the idea is to get the measurement right!

The problem is if they are too short you will have threads showing and its easy to take a little off but not so easy to add extra length on :(

Of course that is the beauty of double walled rims but I much prefer the Brompton ones over the Sun CR18 rims which are quite a struggle to get tyres off and on.

Jerry
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
Hi James,

36v7ah lithium battery for electric bicycle, View 36v lithium battery pack for ebike kits, Product Details from Changzhou Hui Heng Vehicle Parts Co., Ltd. on Alibaba.com

Depending on the saddle, the retaining block would have to be clamped 100mm below the saddle base which means the seat post could not be retracted down far enough for the frame to lock up when being carried.
I remember now, I'm sure you've linked to it before.
Yep, that's what I thought but couldn't get an idea of size. The link that you posted has a pic of the battery mounted on a bike and it really highlights that it's not going to work in that position on a Brompton.

I do use an extended seatpost, needed for my height. The extra height of the B whilst folded doesn't bother me as it still fits my requirement of fitting under a desk and more importantly under a cafe table :D

Thanks for your kind offer.

James
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
Of course that is the beauty of double walled rims but I much prefer the Brompton ones over the Sun CR18 rims which are quite a struggle to get tyres off and on.
Jerry
Hopefully they'll be the right length!
I've just fitted a Marathon Plus tyre to the rear which was interesting enough on the Brompton rim so I wouldn't want to have to do that on the Sun CR18 rims.

Apparently the 2013 rims and the other upgrades aren't going to be available separately for ages yet.

Brompton launch new rims, brake levers & tools for 2013 | road.cc | Road cycling news, Bike reviews, Commuting, Leisure riding, Sportives and more

The pic shows the rear wheel as being angle drilled so I presume the current one isn't?

The new brake levers would have been good for conversions as they would allow more room on the M style handlebar and are supposed to have better leverage but I'm guessing there's no way of setting them up as a cut out brake as well.

The New Brompton Brake levers | Flickr - Photo Sharing!
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
I asked about getting batteries from the ebay kit supplier.

http://i1105.photobucket.com/albums/h360/19Bikesales/36v6ah_zpsd41a53f2.jpg

His response was that they are the same cells as in the ebay listing of the 9ah battery and the shrink wrap amps 6-8ah is of same price and same size.

Also available in A123 LifePO4 but will be heavier and more expensive than the Li(NiCoMn)O2(NCM)cell pack

PVC Battery Pack dimension:
Thickness Max 80mm
Width Max 110mm
Length Max 220mm
Weight approx 3kg
Price: £220
 

benjy_a

Esteemed Pedelecer
Jul 25, 2009
417
26
Having been using my Brompton now for a year, I have over 5000 miles of experience with multiple folds each day.

Battery in the front bag is the way to go. I use a system the same as electricwheel co. which is connectors in the luggage block, controller on handlebars. This means no wires at all to connect, just pop the bag on and go.

Battery on the seat post is asking for trouble; wires everywhere interfering with the fold. Wires will also degenerate after repeated folding and be likely to break. I can't imagine a worse place for a battery on a Brompton.

Ben
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
5000 miles is a lot!

Newb question: what happens when it rains on the front luggage block connection? It seems the most convenient way of connecting the battery to the bike, especially with the controller on the bike as well.

When i had my Bafang and frogpack on the seatpost I did have to get the wife out of bed to come pick me up once at 11pm at night coming back from work because I didn't realise the battery wire had got caught in the rear suspension and broke it. Next time I'm calling a cab, not worth the agro!

I can see you could argue either way, if the battery's at the back it's more wires around the bike and could degenerate with folding. If it's at the front you have more weight over the front wheel if you hit a pothole etc. and the front luggage block and bolts could take a hit.

You still rocking the Crystalyte G209 Ben? You were asking about Bafang's at one point weren't you?
I do like the idea of the G209 because you can swop it out for a normal front wheel easily if you wanted to (ie you knew you would be carrying it for a bit).

James
 

GaRRy

Esteemed Pedelecer
May 18, 2012
1,019
3
Tamworth
Exactly what I tried to tell him. The front wheel would be dropped lower than the rear wheel!

Thanks for the pic (I hope you don't mind that I cut and pasted it) as I have never seen them side by side like that before

View attachment 4941
So how the hell are they both 16 inch rims ?

Just curious
 
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jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,292
112
Cambridge, UK
Its not just 16" wheels other sizes like 20" and 24" can have different ERDs "effective rim diameter". Few rims are actually the specified diameter once you put the tyre on. Again depth of tyres vary so room for different measurements there.

The late great Sheldon Brown explains it more clearly than I

Tire Sizing Systems

Jerry
 
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benjy_a

Esteemed Pedelecer
Jul 25, 2009
417
26
5000 miles is a lot!

Newb question: what happens when it rains on the front luggage block connection? It seems the most convenient way of connecting the battery to the bike, especially with the controller on the bike as well.

When i had my Bafang and frogpack on the seatpost I did have to get the wife out of bed to come pick me up once at 11pm at night coming back from work because I didn't realise the battery wire had got caught in the rear suspension and broke it. Next time I'm calling a cab, not worth the agro!

I can see you could argue either way, if the battery's at the back it's more wires around the bike and could degenerate with folding. If it's at the front you have more weight over the front wheel if you hit a pothole etc. and the front luggage block and bolts could take a hit.

You still rocking the Crystalyte G209 Ben? You were asking about Bafang's at one point weren't you?
I do like the idea of the G209 because you can swop it out for a normal front wheel easily if you wanted to (ie you knew you would be carrying it for a bit).

James

James,

Water on the front block causes no issues, it rarely gets wet in any case as it's protected as soon as the front bag is placed onto the bike.

I'm happy with the strength of the luggage block; 5000+ miles of potholed lanes and London roads and (touch wood) nothing has shifted. I have a 7.5kg battery in the bag, plus daily luggage (16S6P lifepo4 A123 pack - 48v, 14Ah).

Yes I'm still using the Crystalyte G series motor, it's (touch wood again) still going strong and I'm very happy with it. I'm very glad now to have the direct drive motor considering the amount of miles that I do (600 per month). The only issue is still that the spokes loosen and click and clunk; Alan (catsnapper) is waiting in the wings to do a rebuild of my wheel in the not too distant future.

One point of note is that the G series motor does not fit straight into the Brompton forks (although I did hear that they may have changed it since I got mine). I still had to widen - have a search for my original build thread if you're interested. Also this motor is too slow at 36V in a 16" rim (below 15mph) hence why I run it at 48v. This of course brings it into a shady area re power output but brings the speed up to that of most other commercially available electric bikes (15-18mph). I use a programmable controller and Cycle Analyst to limit current.

Yes I did consider Bafang for a while but couldn't source a motor of the correct speed for the 16" wheel so I gave up looking.

Ben.
 

superDove

Pedelecer
Oct 24, 2011
193
35
Cheshunt, Herts. UK
Got around to lacing the wheel. This is the first time so as advised I used Roger Musson's ebook as a guide.

How does it look?

IMG_0591.jpg

I was going to do radial build but then for some reason ordered spokes for a 1x build. Doh! A case of either too much or too little caffeine at the time.

Have a problem now though. After the first pass of tightening the spoke nipples it looks like the spokes are too long. Are they too long or have I laced the wheel wrong?

motor laced rim view.jpg

If I've laced it right (dubious), I guess I'm going to have to order some more and start again? If the wheelpro site calculation came up too long can anyone tell me what length to order now?

I also did a quick freewheel test but that didn't seem too good? Any thoughts?

[video=youtube;ydzzRMEkE9c]http://www.youtube.com/watch?v=ydzzRMEkE9c&feature=youtu.be[/video]

As always, your help is appreciated!

James
 

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,224
1
If I've laced it right (dubious), I guess I'm going to have to order some more and start again? If the wheelpro site calculation came up too long can anyone tell me what length to order now?
Hi, I used 118mm spokes (cross-1 lacing pattern) for my 36 holes rims (Sun CR18 16" 1-3/8 349mm). I used the Spocalc.xls spreadsheet from Sheldon Brown's website.



More info in my build thread:

http://www.pedelecs.co.uk/forum/electric-bicycles/4747-diy-stage-4-16-wheel-lacing-building-photos.html