Electrifying my Dahon Mu Uno

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Jun 10, 2022
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This continues a thread I started in the "Technical" section, and if you refer to that, it'll get you up to date with the story so far. I'll kick off here by re-posting a photo of the bike as it is right now. Next I'll be ordering a replacement rear wheel based on a Sturmey Archer S2C coaster hub, and sometime later ordering the Swytchbike components. I appreciate that, compared to most of the more exotic (and definitely much heavier and more expensive) constructions detailed in E.S., my little ol' Mu Uno must seem very basic and modest. It's not so much an e-Bike, more like an e-SOS (Scooter On Steroids).
 

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There aren't a lot of build threads on folders, so it will be a good reference for people who want to do a project like that. I put a Grin geared motor kit on my non-electric Brompton a few weeks ago. We also have a factory Brompton Electric for my wife. It would be an easy project for most people and Grin has an excellent Youtube video on how to do it. Wiring in a headlight and replacing the bottom bracket with a torque sensing bottom bracket were the most challenging parts of the project. The bottom bracket was only challenging because the old Campagnolo tool I had kept slipping removing the old bottom bracket. A new Park tool made short work of it.
 
Another view of my rear end (if you'll pardon the expression). Apart from installing the PAS out of sight and out of harm's way on the RHS behind the chainwheel. my aim is to make the whole set-up as uncomplicated and un-cluttered as possible. The cable from the PAS will run along the bottom of the main frame member to the Power Pack, which is fitted on the luggage mount at the front of the frame by means of a Brompton Block. I estimate the all-up weight when completed will be around 25 pounds! (And it will still fold).
 

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Having done some more research, I now reckon that the all-up weight of the completed bike will be approximately 26 pounds (and it will be still foldable and extremely portable!)
 
The Sturmey Archer S2C hub I tracked down has just been delivered by courier, and I'll spend some time now choosing an appropriate wheel rim to order - I'll get a local bike firm to build the wheel for me. Then, as soon as funds permit, I'll order the Swytchbike outfit.
 
tonythebrit said:
The Sturmey Archer S2C hub I tracked down has just been delivered by courier, and I'll spend some time now choosing an appropriate wheel rim to order - I'll get a local bike firm to build the wheel for me. Then, as soon as funds permit, I'll order the Swytchbike outfit.

I watched this video on the kit. Hard to find real reviews since there's so many that are more like ads, but this one, even though the guy has some association with Swytch from testing earlier version, it pretty balanced. The second half of the video compares a lot of the options out there for, in his case the Brompton, but I would imagine apply to a lot of folders:
https://www.youtube.com/watch?v=xxxF241364w
This review is pretty good too, comparing the Swytch to another unit. It also mentioned problems that you may encounter over time with the kits.
https://www.youtube.com/watch?v=X9nC-A-0jLQ
Seem like a decent kit.
 
Thank you E-HP for your input. I checked out both of the Youtube vids, and while they were very informative, many of the features that both systems incorporate were hardly in the spirit of the simplicity that I'm looking for. Apart from the ARCC system, which I'm already aware of, there are 2 others I've now found out about - Cytronex and Nano (both British-made I think). In the end, I still feel that I favour the Swytchbike system. BTW maybe you're aware that the latest available Swytchbike version incorporates a very, very compact battery.
 
Now, there's one small problem that's arisen in my mind for when the time comes to fit the Swytchbike installation, and it's one that wouldn't occur for a bike with multiple gears. Because basically I only have a single gear, and given that the speed of the motor depends on the actual pedalling speed, how do I work out the optimum gear value I should aim for, as calculated by the number of teeth on the chainring and the number of teeth on the rear cog. For instance, my Mu Uno at present has a 54-tooth chainring and an 18-tooth rear cog, which produce a gear value of 57 inches with the 20" wheeels (and 78 inches when engaging kick-shift). Bear in mind a couple of things; firstly, that UK regulations limit my speed to 15-point-something MPH, and secondly, if I needed to change the gear value, I appreciate that it would be cheaper to change the rear cog rather than the chainwheel. Advice please.
 
tonythebrit said:
https://www.youtube.com/watch?v=UkMSn-wE3vE
( don't think I successfully posted the Youtube URL, so I'll try again). Now you know why I like the Mu Uno!!

To post a Youtube link, copy everything after the /watch?v= , click on the youtube button and paste it between the ][ brackets.

[youtube]UkMSn-wE3vE[/youtube]
 
The video was filmed at a presentation to mark the launch of the new Dahon Mu Uno at a trade show in Tokyo in 2010. In fact, I bought my bike at about the very same time in a local bike shop, but can't remember how much I paid for it - about £500 or £600 I think.
 
tonythebrit said:
The video was filmed at a presentation to mark the launch of the new Dahon Mu Uno at a trade show in Tokyo in 2010. In fact, I bought my bike at about the very same time in a local bike shop, but can't remember how much I paid for it - about £500 or £600 I think.

Dahon Girl not included...
 
On Saturday I took the S2C hub to my local bike shop guy for him to build the new wheel for me - using a Halo 20" BMX rim and black spokes & nipples. I also had a long think about the optimum gear ratio for my single-speed when I electrify it, and decided to keep the chainring/cog ratio the same (i.e. 3:1), but reduce the sizes in proportion. Therefore I'm fitting a 42-teeth chainring & 14-teeth rear cog, to replace the present setup of 54/18. I just think a smaller chainring looks neater, and I did say this was going to be minimalist!
 
Picked up my new wheel from the bike shop this morning, and I'm really pleased with it. I'll have to improvise where the brake arm from the coaster hub attaches to the bike, due to the fact that a Mu Uno doesn't have regular chain stays, but no big problem. Sadly though, I can't do any work on the project right now, due to the fact that I loaned my tool kit to my grandson to fix his own bike. He'd better get it back to me very soon, or else . . . . !
Before I forget, there was one other slight problem arose. In keeping with the general "Stealth" theme, I wanted to equip the bike with as many black components as I could, and I've been generally successful in this. However, when I attempted to source a 14-teeth rear cog in black (Sturmey Archer Part HSL714), it seemed that absolutely every supplier in UK only had the chrome version (HSL852) in stock, so that's what I'm compromising with at the moment. I've now discovered that United Bicycle Supply of Ashland OR have HSL714 in stock, so I've emailed them to see if it's viable to have one "shipped over". Fingers crossed!
 
That is the problem with lending out tools. You never have them when you need them. I bought my son-in-law one of those Bikehand tool kits for Christmas. He has been making good use of it.
 
Having checked out United Bicycle Supply's website properly, I now realise they are a wholesale company, and will only supply through local dealers in the US. I may have to rely on a VKP (very kind person) offering to help!
 
Nice try! What caught my eye was the comment "Does not ship to United Kingdom". However, if some kind person . . . .
 
Re. the advertisement on ebay for the 14T sprocket in black, I emailed the seller, basically asking why they wouldn't ship to U.K. So he replied that he would amend the ad to remove the restriction for U.K. I thought this was very helpful, but when I realised what the overall cost would be, I had second thoughts. It was going to cost the best part of 30 bucks, including freight charge and import duty, a lot to pay for a little 14T sprocket!
 
tonythebrit said:
It was going to cost the best part of 30 bucks, including freight charge and import duty, a lot to pay for a little 14T sprocket!

If you really want it, then you’ll be reminded of it every time you ride the bike, so better to buy once, cry once. If you don’t want it, not an issue.
 
I agree with E-HP, if you want it, get it. It isn't that much money in the overall budget for building an ebike. That said, you probably won't notice the silver one after it gets a little dirty. Well, you might, but other people won't.
 
Thank you guys for your input. I think I'll follow my instincts on this, and give it a miss! I'll just use some paint on the chrome one, and kid myself. After a while, the bits that the chain hasn't worn off will still probably show as black!
 
There's still one small problem that's been bugging me. Although it's not necessarily e-bike related, as it's part of my overall project, I guess it's OK to mention it here. As I already said, I've got to make modifications because the Sturmey Archer S2C rear hub is designed to be fitted to a bike with regular horizontal chainstays, which my Mu Uno has not got. So I'm sort of improvising, and then it ocurred to me that if I could change the orientation of the brake arm on the hub, i.e. pointing almost vertically rather than horizontally, then I wouldn't have to manufacture anything unwieldy to connect it to the bike. Does anybody out there have any knowledge of this hub? Can you alter the orientation of the brake arm? Is it a question of loosening off the lock nut on the non-drive end then moving the arm to the required position? I would be grateful for any advice.
 
Oh, I forgot to mention that the axle has flats to correspond with the drop-outs, so it's not a question of rotating the whole hub into the required position, In only it were that easy!
 
If the axle has flats that fixes the position of the torque arm, you can fabricate or buy a different torque arm or add an additional piece to the torque arm. There are a lot of threads on torque arms as they are used with hub motors as well. The torque arms sold by Grin are very good.

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