eBrompton Build

[jerrysimon]

When we first built them we use to lace them up 1X but soon realised that radial lacing was sufficient (strength wise) for such small wheels. This also made the spoke angle and building more managable/simple

As you can see on the wheel in the front of the picture (black Brompton) this was a 36H motor hub. Back then we managed to get the last few 16" ETRO 349 wheels that were drilled 36h. That was one of the first wheels I ever built, but as I said later we got motors with 28H which made everything much easier.

 

[jerrysimon]

Last post today

We use to use these which are single walled but obviously now you can get better double walled ones for the Brompton. Back then all Brompton rim holes were drilled straight whereas now, for the rear at least, I think they are drilled at an angle.

16 x 1 3/8 Rim Single Wall Silver 28H

- 16 x 1 3/8 Silver anodised rim - Single wall standard width - 28 Hole x 14 gauge spokes - Schrader Valve – V8.5 - ETRTO: 349 - ERD: 335mm - External Width: 26.4mm - Internal Width: 19.8mm - Profile Depth: 16mm -Weight: 240g Bargain alternative for Brompton!

www.sjscycles.co.uk

 

[guerney]

While seeking wide rims for 1.75" tyres for my 20" wheeled folding Dahon, I found these made by Litepro. I read somewhere on these forums that Litepro manufacture frames and parts for Brompton. But again, too narrow, and it's the same story for Litepro's 20" rims.

15.15￡ 14% OFF|Aluminum Bike Rims | Aluminum Wall Rim | Brompton Litepro | Bicycle Rim 349 - 349 16x1-3/8 - Aliexpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[jerrysimon]

Looking again at SJSCycles it appears some Brompton rims are only suited for rear/hub builds and as the spokes are crossed I guess that is why the angles are more and thus the holes drilled at an angle. They specifically say not for front wheels/two speed rear wheels or radial built wheels. As I said as long as the spokes on the electric motor hub are built radial, straight drilled holes would be fine. I guess you could use the double rim Brompton front wheel rim shown below, but to be honest all mine are single walled and have lasted years.

Brompton 16 x 1 3/8 349 Rim - 28H

For all Brompton front hubs (incluing hub dynamos) and 2 speed rear hub. Not compatible with Internal Gear rear hubs Weight: 315g ERD - 328 Please note Brompton have selling restrictions to some countries who have their own dealers. If you are unsure please contact our sales team.

www.sjscycles.co.uk

We did also use the Sun CR18 double walled rims but they were a nightmare to get Marathon Plus tyres on!

 

[StuartsProjects]

Looking again at SJSCycles it appears some Brompton rims are only suited for rear/hub builds and as the spokes are crossed I guess that is why the angles are more and thus the holes drilled at an angle. They specifically say not for front wheels/two speed rear wheels or radial built wheels. As I said as long as the spokes on the electric motor hub are built radial, straight drilled holes would be fine. I guess you could use the double rim Brompton front wheel rim shown below, but to be honest all mine are single walled and have lasted years.

Brompton 16 x 1 3/8 349 Rim - 28H

For all Brompton front hubs (incluing hub dynamos) and 2 speed rear hub. Not compatible with Internal Gear rear hubs Weight: 315g ERD - 328 Please note Brompton have selling restrictions to some countries who have their own dealers. If you are unsure please contact our sales team.

www.sjscycles.co.uk

We did also use the Sun CR18 double walled rims but they were a nightmare to get Marathon Plus tyres on!

Thanks for the info, very useful.

I saw the 'not for rear wheels' comments. And the Brompton electric rim but that uses cross over spokes.

I think a standard double wall will do. The single wall is stupid cheap (£12), but given the number and size of potholes that have become the norm on roads these days, the stronger rim is probably a good idea.

 

[guerney]

We did also use the Sun CR18 double walled rims but they were a nightmare to get Marathon Plus tyres on!

I find tight reusable zipties either side of the final bulge, hold that in place for pushing in.

We did also use the Sun CR18 double walled rims but they were a nightmare to get Marathon Plus tyres on!

I looked at those, but as I have no experience of wheel building, and would have paid my lbs to make them, I bought a pair of compatible entire Tern wheels for less than twice the price of those rims. Worked out cheaper overall because of the lbs's wheel building service price, a bonus being two old hubs which I can use in future.

 

[jerrysimon]

I find tight reusable zipties either side of the final bulge, hold that in place for pushing in.


I looked at those, but as I have no experience of wheel building, and would have paid my lbs to make them, I bought a pair of compatible entire Tern wheels for less than twice the price of those rims. Worked out cheaper overall because of the lbs's wheel building service price.

If you want to learn how to build wheels then 16/20" is the place to start. Plenty of youtube howtos and info on line. Small wheel builds are easy. I had to learn as 13 years ago it was impossible to get anyone to do electric hub builds for Brompton/small wheels. Radial makes it even easier. Years ago we did posts on here about how we learnt.

I can now do large wheels including rear wheels/dishing etc. I am not an expert, but have built loads for my various bikes which have performed perfectly well.

Here is a few builds I have done on the Brompton wheels.



From left to right SRAM auto change 2 speed which was on my Brompton for a while. Two speed rear Brompton wheel and a radial front on a double walled Brompton rim.

 

[jerrysimon]

I hope I am not hijacking this thread just say

I use to post several times every day on this forum for years when I was learning this stuff.

If you are interested here are my Tongxin 36v, 180w, 260RPM, 28h motors. Not sure if you can still get them. They are only three wire not hall sensored. The beauty is they have steel roller bearings inside not gears so are vertually silent when running. I use to purchase them in pairs as it was cheaper direct from China for shipping. No Paypal back then, so we paid up front directly into accounts and often waited 6 weeks for delivery with no guarantees!

The Chinese to English transulation often ended up confused hence we ended up with motors with roller brakes on them, wrong number of holes etc etc. It got better and the sellers always delivered and were honest. It really was an act of faith sending them money.







They were 80mm widebetween shaft bearings, 120mm diam and needed spacers to stop the forks fowling, so the Brompton forks needed to be spread about 8-10mm and fork cutouts widened for the larger motor shafts!

Just over 2.1Kg, maybe new ones are much lighter now ?



PS just re-read thread and looks like the ones you are using now are a little bit lighter. When we fitted these they were at least 0.5kg lighter than the equivalent traditional geared motors. Maybe the ones now are also higher than powered ?

These draw about 2 amps when you pedal assisting on the flat and a max of about 6-7amps (set) when you are going up a hill. There's only one in Cambridge!

With the controllers back then we could re-program it to ensure we kept the current down and stopped them slipping on their clutches etc.

 

[StuartsProjects]

Just over 2.1Kg, maybe new ones are much lighter now ?

Looks like, I dont have the weights for just the motors, but the weights for the complete wheel, no tyre, tube or tape are;

Swytch front motor wheel 2.01Kg

TBK-74AD front motor wheel 1.906g​

 

[jerrysimon]

Looks like, I dont have the weights for just the motors, but the weights for the complete wheel, no tyre, tube or tape are;

Swytch front motor wheel 2.01Kg

TBK-74AD front motor wheel 1.906g​

This is my wheel. On the TopBikeKit website it says their motor is 1.6kg which is impressive.

Are they quiet ?

 

[StuartsProjects]

Are they quiet ?

You can hear the TBK-74AD, but its not noisey and the Swytch motor is quieter.

 

[guerney]

If you want to learn how to build wheels then 16/20" is the place to start. Plenty of youtube howtos and info on line. Small wheel builds are easy. I had to learn as 13 years ago it was impossible to get anyone to do electric hub builds for Brompton/small wheels. Radial makes it even easier. Years ago we did posts on here about how we learnt.

I can now do large wheels including rear wheels/dishing etc. I am not an expert, but have built loads for my various bikes which have performed perfectly well.

Here is a few builds I have done on the Brompton wheels.

View attachment 51673

From left to right SRAM auto change 2 speed which was on my Brompton for a while. Two speed rear Brompton wheel and a radial front on a double walled Brompton rim.

Thanks for the encouragement. Given their increasing rarity, the day will come when I will have to build my own wheels. I've seen very interesting Youtube videos about wheel building. Looks like you live in a straight gravity area. It's another postcode lottery I suppose. That's my excuse and I'm sticking to it.

 

[guerney]

So good for the eBrompton motor wheel I thought, but I was disappointed, they wont stay on the motor wheel rim, when the tyre gets up to pressure it tries to escape the rim, see picture.

I spotted these... long wait for delivery, and they might turn out to be rubbish or otherwise unsuitable, but:

1PC Bicycle Rims 16 Inch 28H 36H Double Deck Aluminum Alloy Wheel Rim 16x1.5/1.75 Tires Fixed Gear Thicken CNC Bike Rim - AliExpress 18

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[guerney]

@saneagle found these cheaper and with faster delivery - there may be rims on AliExpress with the right number of holes of the same brand:

Page Not Found - Aliexpress.com

 

[guerney]

28H, 36H. Although rim width sizes aren't mentioned (in English at least), Google lens is translating text in the chart below as 30mm height and 25mm width ... best have a chat with the seller. AliExpress Standard delivery speed, which seems to be about 2 weeks in my experience.

https://www.aliexpress.com/i/32951467441.html

 

[StuartsProjects]

Brilliant Bikes (in the UK) sell a standard front wheel Brompton double walled rim for £28. Rims from Aliexpress are around the same price.

I would be confident that Brilliant Bikes will supply the geniune article, I would not be sure about a dealer on Aliexpress.

 

[guerney]

I managed to avoid buying from AliExpress for years, because nearly every time, I've searched for and found exactly the same item being sold on ebay, shipped from the UK for about the same price. Ebay have never refused me a refund, getting money back from AliExpress isn't easy, as I discovered recently. Trouble is, new products appear on AliExpress first.

 

[guerney]

Lightest Brompton I've ever seen: 7.1kg

Super lightweight Brompton | ETA

Bromptons have become the go-to folder for rail commuters, but you'll be lucky to spot this one-of-kind custom superlight version by Derek...

www.eta.co.uk

The same guy's 5.9kg folding bike; custom carbon parts:

The world's lightest Brompton | ETA

The world's lightest folding bicycle has been built by a talented engineer who wanted to take his mind off his health problems. And what a job...

www.eta.co.uk

 

[StuartsProjects]

Early trials

Fairly often when ordering stuff on eBay if they do ‘Click and Collect’ I will have it delivered to the Argos in Sainsbury's which is about a 5.6km journey each way and about 80m in height of hills to climb, or around 260 feet of climbing in units that most of us grew up with.

To give eBrompton a trial, whilst waiting for supplies of 21700 5Ahr cells to turn up, I bought a Hoverboard battery, its 10S2P @ 4.4Ahr of allegedly Samsung 18650 cells and cost £50 delivered, it arrived the next day too. It weighs 965g.



eBrompton has not been upgraded to shopping trolley mode, so when I arrived at the store I carried the folded eBrompton, with battery still in bag by its built in handle (the saddle nose) to the Argos outlet at the back of the store. I carried eBrompton about 75m. Would not want to carry it much further, but I could manage it. So for local trips such as to small shops if your ebike does not have shopping trolley mode, its quicker to fold up the bike and carry it rather than lock it up outside. I was going to say the same would apply when visiting the doctor or dentist, but most people wont remember what they are.

The route home to shop only has a couple of hundred meters of main road, the rest is about 50:50 quiet residential streets and cycle paths. I mostly rode on assist level 2, but on a couple of the steep bits I put it up to level 5. The motor and battery seemed to cope with this well enough.

When I got back to my house, I waited 60 seconds and made a note of the battery volts, it was 36.2V. When I get some ‘better’ batteries I can use this 11km hilly route as a standard to compare batteries against. If I get a battery that would do the route twice, that would be enough for my needs, for longer trips just carry another battery.

 

[Solarbake]

Hi nice thread my standard Brompton with Swytch kit with modified battery mount and cadence sensor mount must weigh it to see the total weight