Brompton q70 motor

[pears_91]

The spokes shouldn't be a problem. I've seen many motor wheels like that even on factory ebikes. If you do another conversion, use 14g spokes and a one cross pattern. Avoid rims with eyelets in the holes because the eyelets hold the spokes at the wrong angle, especially if you use 13g spokes.

I had good results with a Sunkko welder, which was about £130. After several years of good service, It has stopped working until I fix it properly. It works when disassembled, but not when I put it back together. There are many stories of them tripping breakers in consumer units because they make spikes in the mains. Maybe I was lucky, but had no problems in two houses. Its welds are very adjustable and predictable once set.

I have since tried a couple of portable welders that run off internal batteries. After some practice, I was able to get some decent welds, but these battery ones are very hit and miss, so you have to do loads of extra welds to be sure. You have to have a delicate touch when you use them. Press too hard and they don't weld. Press too soft and it blows holes in the metal.

I've now got one of these adapted to take the heavier electrodes from a battery one because the electrodes and leads that come with it are too small. I'm full of hope, but I can't try it until I've made up a set of heavy duty leads for the battery. I'll let you know in a week or so how it works.
View attachment 54269

Thanks saneagle I'll take that onboard about the spokes and although it doesnt sound critical I will try to improve it at some point because I've also spoked it up with the valve between the crossover of spokes so it's possible but not so easy to get the pump head on the valve.

The one you showed in the picture looks very similar to the one I used.. mine was a red one available on Amazon. I didn't get very good results,, but it does seem Abit of a common theme with me doesn't it.. I have seen a YouTube video of someone using the very same machine and getting good results,, the main feedback I gained from that video was he was bringing them down at an angle rather than straight down (perpendicular) onto the battery like I had.

 

[pears_91]

What question are you actually asking ?

There are a large number of electric Brompton wheels in use around the world.

I have two that I have ridden and they are fine.

I dont understand a need for a 'solution' for the spokes.

hi stuart

my spokes are bent,, because the angle as the motor diameter is bigger than a standard hub,, you can use smaller spokes but the bigger the hub gets the bigger the angle the spoke has to be at to connect to the rim.

The holes for the spokes in the rim seem to be all in the centre coming out at 90 degrees to the hub.

It does feel fine to ride and sturdy, but just looks abit funny and although it feels ok im sure it will be weaker as a result, like I wont be throwing myself off curbs as confidently. Also because of the position of the valve as mentioned in previous message I am going to re-building the wheel soon so open to ideas of things I can change to improve this..

I have since been looking at other rims online and I can see there are ones called 'straight drilled' and others called 'angle drilled' I'm not 100% yet but I am assuming this is referring to the spoke holes being at an angle which should help solve this problem. But also I will consider using slightly smaller spokes and nipples that I can imagine may allow for more freedom of movement.



Battery wise,, its covered up with heat shrink now so i cant show much in picture.
voltage across it and at all points measures exactly as it should.
the strip i used to connect them had some holes blown in it during welding.
but still welded were secure.

For now I'm just going to use it but charge and store it in the garage.
I do hope to be making more battery powered things in future so will think about getting a better machine for spot welding and or just practicing my technique. Add if it makes sense ill make a new battery for the bike as its something I will be using daily for years to come hopefully.. and move this battery onto something else that might be used less frequently and that would be permanently kept in the garage or shed for example.



to be honest the battery cells I bought say ' not to be connected by the end user' or something along those lines.. So strictly I don't think any member of the public should be making battery packs themselves.. similarly I have a throttle on the bike which also is strictly not allowed.. but i take it all with a pinch of salt and off course know there is some risk to it.

 

[StuartsProjects]

This is a Swytch Motor Wheel for a Brompton, spokes look fine to me, nice and straight;

 

[pears_91]

This is a Swytch Motor Wheel for a Brompton, spokes look fine to me, nice and straight;

View attachment 54291

Yes,,, your spoke holes in rim seem to be offset at an angle to eachother. Rather than all straight through the centre like mine.

I did consider going for the swytch kit and would have been much more straightforward I'm sure.

Did you get full kit from them? And finding it all ok or made any modifications to it?


I will get some pictures over the weekend.

 

[StuartsProjects]

I did consider going for the swytch kit and would have been much more straightforward I'm sure.

Did you get full kit from them? And finding it all ok or made any modifications to it?

I did get a full Swytch kit around 3 years ago and fitted it to a 20 year old M3 Brompton.

I have since done a DIY conversion on a highly modified C3, the kit, including motor and controller etc came from TopBikeKit, full story of the conversion is here;

eBrompton Build

That electric Brompton weighs around 12Kg, compared to about 18Kg for the old Swytch converted Brompton which became too heavy for me to handle.

The Swytch electric kit from the old M3 Brompton has been removed so that I now have a 3 speed manual Brompton that weighs 12Kg so OK to handle and is fine for local shopping trips etc. I intend to upgrade the gearing to a 6 speed, maybe 9 speed, with a wide ratio Sturmey Archer hub that I picked up second hand with spokes and cogs for £40. Booked a wheel building course at the local cycling charity and after that I will build the wheel.

 

[pears_91]

This is a Swytch Motor Wheel for a Brompton, spokes look fine to me, nice and straight;

View attachment 54291

My motor has 36h and a lot of them for Brompton seem to have 28h like I can see yours is.

Your valve for pumping though seems to be like mine inline with a crossover of spokes.. maybe it's just from the angle of the picture but seems like it would be easier to access if it were between spokes that don't cross.

 

[StuartsProjects]

Your valve for pumping though seems to be like mine inline with a crossover of spokes.. maybe it's just from the angle of the picture but seems like it would be easier to access if it were between spokes that don't cross.

Crossed spokes ?

All radial laced.

 

[saneagle]

Yes,,, your spoke holes in rim seem to be offset at an angle to eachother. Rather than all straight through the centre like mine.

I did consider going for the swytch kit and would have been much more straightforward I'm sure.

Did you get full kit from them? And finding it all ok or made any modifications to it?


I will get some pictures over the weekend.

He's used a radial spoke pattern, so there's no angle to any spokes. If yours are angled, then you've done a 1-cross pattern, which is better, but only if the spokes are free to take the correct angle. Why don't you show what you've done? Which spokes (gauge) did you use?

The portable battery operated welders all seem to work the same. They use a different principle to normal spot-welding. In normal spot welding, you need pressure to ensure all the current goes through the material yo want to weld. If you use pressure with the portable ones, the resistance is too low and more current than what the device can give tries to flow, and it collapses. The idea is to use less pressure so that you have higher resistance and make more heat . As I said before, If you press too hard, you get no weld; if you press just right, you get a good one, and if you press too light, you get sparks that blow through the metal. Basically, you're using your feel to adjust the quality of the weld. I found the best technique is to press down hard to make sure that the strip makes good contact with the battery, then release the pressure enough just to hold everything in place while I pressed the switch. That's no so easy on the ones that weld with a timer delay because it goes off when you're not ready.

 

[pears_91]

He's used a radial spoke pattern, so there's no angle to any spokes. If yours are angled, then you've done a 1-cross pattern, which is better, but only if the spokes are free to take the correct angle. Why don't you show what you've done? Which spokes (gauge) did you use?

The portable battery operated welders all seem to work the same. They use a different principle to normal spot-welding. In normal spot welding, you need pressure to ensure all the current goes through the material yo want to weld. If you use pressure with the portable ones, the resistance is too low and more current than what the device can give tries to flow, and it collapses. The idea is to use less pressure so that you have higher resistance and make more heat . As I said before, If you press too hard, you get no weld; if you press just right, you get a good one, and if you press too light, you get sparks that blow through the metal. Basically, you're using your feel to adjust the quality of the weld. I found the best technique is to press down hard to make sure that the strip makes good contact with the battery, then release the pressure enough just to hold everything in place while I pressed the switch. That's no so easy on the ones that weld with a timer delay because it goes off when you're not ready.

Ill post some pictures over the weekend, Id say it's currently a 2 cross, not sure about the spoke gauge, I'll find out by measuring.

Probably I should get a new rim that has angled holes.. the q70 has 36 holes though so not so easy to find as the 28h rims.



I think a foot pedal would be very useful from what you are saying.. mine was going off as soon as contact was made, so as you say very difficult to control the pressure.

 

[pears_91]

Crossed spokes ?

All radial laced.

Indeed it is,, I was confused by the picture angle

 

[saneagle]

Indeed it is,, I was confused by the picture angle

So was I at first. I had to study it to see what it actually was.

 

[pears_91]

Here are some pictures

Needs cables tidying still,, but you can get an idea of the spoke pattern and bending.. they are like a gentle s shape bend. 2mm diameter spokes.

I can't find a rim available online that has 36 holes with angled holes. Angled ones are available for Brompton with 28 holes and it sounds like a fancy spoke pattern with different length spokes will make that ok to thread 36 hole hub onto 28 hole rim.

The battery pack I'm very happy with how compact it is.. I don't know how long the juice will last in reality yet.. but it's 36v 7ah. So in theory at 250 watt it should last 1 hour.

The motor is very powerful on full throttle level 5 assistance, I don't see the need for anything more and can see why that's the legal limit for a bike to be honest.. feels like your going down hill when your going up hill with just a little peddling your flying. My partner had a go and it's quite funny to watch someone on a Brompton traveling up hill that fast.

 

[saneagle]

I think those spokes will be OK. I've seen worse. maybe check the tension after a few hundred miles. You'll probably be OK if you can find a rim without eyelets. I'm pretty sure that I used the same rim as you (Sun CR18) when I built one. I used straight 14g spokes, which I cut down from longer ones and threaded them myself.

 

[pears_91]

I found a solution to ease my worries about battery.. a LIPO fire proof storage bag.
for less than 10 quid and what we hear about fires and e bikes surely they should be essential?

 

[pears_91]

I think those spokes will be OK. I've seen worse. maybe check the tension after a few hundred miles. You'll probably be OK if you can find a rim without eyelets. I'm pretty sure that I used the same rim as you (Sun CR18) when I built one. I used straight 14g spokes, which I cut down from longer ones and threaded them myself.

Yes that's the rim I bought,


Out of interest what tyres do you use on it? I've got the marathons and they are very tight fit on this rim.

I'll leave it all be for now and keep an eye on it.. but I can see me threading it onto the original Brompton 28h rim that I removed.. it doesn't have eyelets and the holes are slightly angled to each side.

 

[StuartsProjects]

Marathon tyres are a tight fit on Brompton rims, especially the Plus, thats normal.

I have stopped using Marathon Plus and have switched to Continental Contact Urbans. They roll very well, seem to be highly puncture resistant, are cheaper and much lighter than Marathons. Easy to fit too, especially to folding version.

 

[saneagle]

Yes that's the rim I bought,


Out of interest what tyres do you use on it? I've got the marathons and they are very tight fit on this rim.

I'll leave it all be for now and keep an eye on it.. but I can see me threading it onto the original Brompton 28h rim that I removed.. it doesn't have eyelets and the holes are slightly angled to each side.

I used a Marathon Plus. I wasn't able to get it on myself. Normally, I never use levers to put a tyre on, but this one wouldn't go on with my motorbike tyre levers. I had to take it to a bike shop, and the guy there couldn't get it on either until he went deep into his tool store and pulled out a 2ft long tyre lever. Using all his strength, he finally got it over the rim.

 

[pears_91]

I used a Marathon Plus. I wasn't able to get it on myself. Normally, I never use levers to put a tyre on, but this one wouldn't go on with my motorbike tyre levers. I had to take it to a bike shop, and the guy there couldn't get it on either until he went deep into his tool store and pulled out a 2ft long tyre lever. Using all his strength, he finally got it over the rim.

I feel you with that,,, I took it off to change the inner tube today. I only just manage to do it with 3 metal tyre levers making the smallest steps around the wheel and pretty much hoping for the best I don't pop the inner tube in the process. I'm not looking forward to getting a puncture in the rain with this one. At least I can fold it up and get on the bus.

 

[StuartsProjects]

I feel you with that,,, I took it off to change the inner tube today. I only just manage to do it with 3 metal tyre levers making the smallest steps around the wheel and pretty much hoping for the best I don't pop the inner tube in the process.

Never had a significant problem myself with the Marathon Plus, but then the rims I have used them on are the 28 hole rims specifically for the Brompton.

 

[saneagle]

Never had a significant problem myself with the Marathon Plus, but then the rims I have used them on are the 28 hole rims specifically for the Brompton.

It's just that Sun CR18 rim that's tricky.