dahon folder conversion - fast and light

[sandyman44]

hi all
so, I am thinking of buying a Dahon Vigor D9 20" folder for london commuting and converting it.
Before anyone says "why not this or that ready-e-biked 20" folder" I have not found a single one (for a sensible price anyway) that has as long a virtual-top-tube frame geometry as this dahon, and I've researched and sat on / ridden a lot. The stretched "almost roadie" riding position is a requirement for me. with the addition of bar ends or aero-clamps then an aero position will be achievable.

so I am thinking rear hub motor because:
a) stealth (hiding behind the sprockets)
b) light weight - want to increase the base weight of the bike (assume battery removed) as little as possible so it remains carryable. Base weight is 11.7kg. I'm a strong chap, fine with 14-15kg on my arm and the rest in a bag over shoulder.
c) maintain gearing ratio which is 53:{11-32} and allow me to increase ring beyond 53 if I want in future. crank drives seem to come with 48 or 46 rings aimed at 26" or 700c, and adapting that seems hard/fiddly. plus the crank drive motor may well impinge on the folded state.
d) I've got the use of a borrowed whoosh crank drive 700c ebike and can't get used to needing to stop pedalling to change gear - being a keen non-assisted cyclist I am always wanting to flick the shifter to keep my cadence right and maintain the power. Assuming rear hub much more accommodating for that.
I have never been anywhere near wheelbuilding so would need a prebuilt wheel or find a builder.
the bike has a 135mm rear dropout and 9 speed cassette which I would want to maintain - a lot of kits seem to be freewheel only?

I'm also pondering on speed requirements. I have some nice flat offroad cycle paths and quiet, well surfaced bridleways so want to run at 20mph or thereabouts. The 36v motors for 20" wheel seem to be sold with around 340rpm spin speed which if I read it right comes out ~20mph? what will it do as that speed is approached or exceeded - stop pushing completely, or worse, generate drag? do I need to look at 48v so that it keeps on pushing at that speed? all the uk kits I have found seem to be 36v?

Next, battery. my range requirement is LOW (7 miles if I charge at work, 14 if I don't, all pretty flat) and again because of the folding and wanting to carry it on a train I want to keep weight down. But I am riding at max PAS, to avoid sweatiness. 10Ah should more be enough, removable and I don't want it all on the back to keep the balance of the bike better.
(again , the borrowed whoosh has a rear rack 17ah which is really heavy and unbalances it at speed/cornering, so I know I dont want that).
So I am thinking battery in a removable touring bag on the front frame-mount luggage truss (not on the bar). Just the same idea as the factory electric brompton. My plan is to remove the battery bag for each train journey and sling it over my shoulder - and so it needs to be built as light as poss and with some form of quick-connect for that reason. Most kits seem to be aimed at bottle, downtube or rack, non of which really suit. Does anyone build/sell battery packs to the general public in that bag-mount style? again do I need to go 48v?

controllers: no idea where to start.. other than if I can put it in the bag with the battery, great.

brakes: I'd like to uprate the brakes on this chap to magura HS33 hydraulic rims. Anyone "been there done that" who knows how they work with ebike cutouts - their spec says it has an "ebike switch"?

ta for any help

 

[Nealh]

Panda are introducing the Swytch system next year currently discounted if you subscribe now.
https://comingsoon-tech.com/swytch-electric-bike-wheel/

Not a recommend but Keyde have a new lightweight cassette hub motor with in built controller, might be a bit pricey.
Seen it on AliEx for about $400/450 though may well be cheaper contacting them direct.
https://www.aliexpress.com/item/2-3Kg-Max-24V-33V-36V-500W-Built-in-controller-disc-brake-cassette-rear-hub-motor/32773366284.html?spm=2114.10010108.1000013.4.1f61d93qffcFB&traffic_analysisId=recommend_2088_2_90158_iswistore&scm=1007.13339.90158.0&pvid=ac59935f-ed52-4599-8a8f-b264fbbe8d57&tpp=1

 

[jwm]

Having read the first couple of paragraphs, I did start to wonder why you want an ebike, even more so with the short ride?

John

 

[anotherkiwi]

c) maintain gearing ratio which is 53:{11-32} and allow me to increase ring beyond 53 if I want in future. crank drives seem to come with 48 or 46 rings aimed at 26" or 700c, and adapting that seems hard/fiddly. plus the crank drive motor may well impinge on the folded state.

controllers: no idea where to start.. other than if I can put it in the bag with the battery, great.

brakes: I'd like to uprate the brakes on this chap to magura HS33 hydraulic rims. Anyone "been there done that" who knows how they work with ebike cutouts - their spec says it has an "ebike switch"?

You can buy chainwheels so big for the bafang motors they would scrape on the ground with a 20" folder... https://www.dutchbikebits.com/alligt-chainrings-60bcd?keyword=alligt&category_id=0

Nope you want to unplug just the battery from the controller so you need to find somewhere to attach it it. Down the back of the seat tube looks like a good spot for it.

You don't need a hydraulic rear brake. You don't need a cut off switch with a hub motor and a modern controller. As long as you turn the bike off or to assistance level 0 when you dismount and push it around, that is when you risk turning the pedal by accident and zoom off it will go if you aren't holding on to it firmly enough A HS11 will be plenty enough but hey! if you have the cash for a HS33... Which I think may have a brake light switch IIRC, not the same thing as a cut off.

 

[Deleted member 4366]

The motor is easy: Q100C. You need the 328rpm for a 20" wheel. It gives 18 mph at 36v, so run it at 48v if you want 20 mph OTR. You can get the battery in an under-seat toolbag from Jimmy at Insat International. A 26 cell one will give you a useable 5AH or 240Wh, which will take you about 20 miles at 15 mph or 10 miles at 20 mph. You can get a 48v 14A Sinewave KT controller from Aliexpress or the 17A one from PSWpower.

 

[DynatechFan]

Having read the first couple of paragraphs, I did start to wonder why you want an ebike, even more so with the short ride?
John

14 miles doesnt seem short to me - and an ebike can be as much about speed/comfort as anything, especially on a commute. An ebike Dohan lightweight commuter sounds like a great idea to me

My round trip is 12 and frankly without a motor it is a very different experience - with a motor I can do either direction (one is mostly uphill, the other down hill) completely sweat free in normal work clothes in 20/25 mins - its a hugely practical way to travel. Faster/cheaper than a car and without parking issues too

 

[sandyman44]

Having read the first couple of paragraphs, I did start to wonder why you want an ebike, even more so with the short ride?

John

I didn't want to bore all with the details but its actually 5.5 miles home-station - takes me 23 mins on ebike non-sweaty in work clothes. To do slow enough to not sweat would mean double at least. if at full pace in lycra - nowhere to change.. and its followed by 1hr on train to london, followed by 1.5 miles across london. starting EVEN earlier to allow non-sweaty pace not sleep/family friendly. It works on the ebike, its the only valid alternative to the car for home-station which I am trying to avoid using.

 

[sandyman44]

Panda are introducing the Swytch system next year currently discounted if you subscribe now.
https://comingsoon-tech.com/swytch-electric-bike-wheel/

Not a recommend but Keyde have a new lightweight cassette hub motor with in built controller, might be a bit pricey.
Seen it on AliEx for about $400/450 though may well be cheaper contacting them direct.
https://www.aliexpress.com/item/2-3Kg-Max-24V-33V-36V-500W-Built-in-controller-disc-brake-cassette-rear-hub-motor/32773366284.html?spm=2114.10010108.1000013.4.1f61d93qffcFB&traffic_analysisId=recommend_2088_2_90158_iswistore&scm=1007.13339.90158.0&pvid=ac59935f-ed52-4599-8a8f-b264fbbe8d57&tpp=1

I've contacted panda already and awaiting a response . swytch is close to how I want to do it but the bag is bar-mount (I want it lower) and its front hub. plus availability long time away.

400 for just the motor and controller seems a lot when there are other motors available for a lot less.

 

[sandyman44]

You can buy chainwheels so big for the bafang motors they would scrape on the ground with a 20" folder... https://www.dutchbikebits.com/alligt-chainrings-60bcd?keyword=alligt&category_id=0

Nope you want to unplug just the battery from the controller so you need to find somewhere to attach it it. Down the back of the seat tube looks like a good spot for it.

You don't need a hydraulic rear brake. You don't need a cut off switch with a hub motor and a modern controller. As long as you turn the bike off or to assistance level 0 when you dismount and push it around, that is when you risk turning the pedal by accident and zoom off it will go if you aren't holding on to it firmly enough A HS11 will be plenty enough but hey! if you have the cash for a HS33... Which I think may have a brake light switch IIRC, not the same thing as a cut off.

ok, so I can see that uprating the chainring may not be impossible. are you saying crank drive is a better than hub for my requirement? I thought that cranks were heavier, or are they more or less the same as hubs? crank drive is an alternative solution to the top speed issue right? so long as the motor + my legs has enough wattage to sustain the required speed, and we have the right gearing, the theoretical top speed with crank is higher (without going to 48v hub) ? what cadence are crank drives optimally geared/wound for?

hydraulics - yes only plan to fit to the front. the rear is internally cabled anyway so replacing it would be a pain. Only thinking hs33 vs hs11 as it says it has the "ebike switch" - can't find much about what that actually is though. if cutoff not needed then fine.

controller - I don't want to put anything other than a light on the seat tube as will be dropping the seat when folding it. I was thinking with the battery in the front bag because I'll have the bag anyway and it'll be waterproof in there .

 

[anotherkiwi]

No just saying (for posterity and Google searches) that you are not limited to stock chainwheels on a crank drive.

Apparently the switch on the HS33 controls both brake light and cutoff. There is another switch available that you splice into the brakeline for the other brakes.

The seat tube is in a housing I was thinking you could attach the controller there. It would mean short cable runs from PAS and motor.

 

[DouglasXK]

Are you thinking of just folding the bike and onto the train, storing it as luggage? There’s some really careless people whose luggage could damage the hub control cable. The Dahon bikes aren’t, or were not, very stable when folded, not on mine anyway. Have you travelled on 20” wheels at +20mph on our crap roads? Frightening. I recently dug mine out and am wondering what to do with it so will follow your progress with interest. Good luck.

 

[Woosh]

Hello SM44,

London is only 1 hour train ride to Southend, come to test a few bikes and spend an afternoon at the beach.
I would suggest you test ride the Zephyr 2017 before starting on the conversion.
The Zephyr 2017 is perfect for your distance, comes with hidden battery, about 35-40 miles range on a full charge, hydraulic brakes front and rear, nice suspension with remote lockout and superbly waterproofed and because it can be folded you can take it into the trains too.

http://wooshbikes.co.uk/?zephyr-2017

I've got the use of a borrowed whoosh crank drive 700c ebike and can't get used to needing to stop pedalling to change gear

The new CD bikes are now fitted with gear sensor, you don't need to slow down or blip the brakes before changing gear anymore.

 

[sandyman44]

Are you thinking of just folding the bike and onto the train, storing it as luggage? There’s some really careless people whose luggage could damage the hub control cable. The Dahon bikes aren’t, or were not, very stable when folded, not on mine anyway. Have you travelled on 20” wheels at +20mph on our crap roads? Frightening. I recently dug mine out and am wondering what to do with it so will follow your progress with interest. Good luck.

not "as luggage" like in the mainline train end of carriage places. in the doorways (london midland). My train has loads of people taking bromptons and 20" dahons like this. bungee to the grab rail inside the door solves stability.
I've spent weeks test riding different folders , this is the only 20incher that I've felt stable on at speed and cornering - more or less like a normal bike. I bombed around some north london streets on it for 1/2 hr last week. if you have a sit-up-and-beg then I wouldn't feel good about going quick on it either..

 

[sandyman44]

The motor is easy: Q100C. You need the 328rpm for a 20" wheel. It gives 18 mph at 36v, so run it at 48v if you want 20 mph OTR. You can get the battery in an under-seat toolbag from Jimmy at Insat International. A 26 cell one will give you a useable 5AH or 240Wh, which will take you about 20 miles at 15 mph or 10 miles at 20 mph. You can get a 48v 14A Sinewave KT controller from Aliexpress or the 17A one from PSWpower.

Q100C looks pretty light @ 2kg, thats what I was hoping for. Do the controllers / PAS LCD setting vary the voltage so say a PAS of 3/5 would keep the top speed down when that is appropriate?

I guess this is old hat to you but I'm a newb.. can you be a bit more specific about which controller, what to look for/how/why ? Is there a really good "primer" I can read? Something with quick connectors rather than lots of soldering..as there is a huge amount of stuff on those chinese sites and very difficult to find your way as a newb.
is any of this stuff available from uk suppliers ?

insat = bga-reworking.co.uk right? am I right that they will custom build battery to whatever size/spec you want? I do prefer the idea of front bag, don't think under-seat will work nicely on a folder - need the upper part of the post for lights, and lower part needs to be able to drop for travel.

thanks

 

[sandyman44]

Hello SM44,

London is only 1 hour train ride to Southend, come to test a few bikes and spend an afternoon at the beach.
I would suggest you test ride the Zephyr 2017 before starting on the conversion.
The Zephyr 2017 is perfect for your distance, comes with hidden battery, about 35-40 miles range on a full charge, hydraulic brakes front and rear, nice suspension with remote lockout and superbly waterproofed and because it can be folded you can take it into the trains too.

http://wooshbikes.co.uk/?zephyr-2017

The new CD bikes are now fitted with gear sensor, you don't need to slow down or blip the brakes before changing gear anymore.

hi whoosh
TBH, an "XL" version of your gallego would be more like what I'd want if it existed. I've sat on soooo many folders that are for small/light people.. Build it with a longer frame , 20" wheels, a strong forward-angled handlepost and a vari-position stem and it'd be an option.
the zephy is too big and heavy for me to contemplate taking on a train.
I'm looking at starting from an 11.7kg bike - adding 2kg for a hub motor, and the smallest battery I can (which will be removable for bike carrying).. so the carry weight target is under 15kg. which is probably comparable to the gallego minus battery.

Is the gear sensor retrofittable to your older bikes ? its a scirocco CD, my dads, he's trashed 1 chain/cassette already.

 

[Jason P]

I would put in a suggestion for the Kudos Secret. Mine has good riding position - with bar ends (Ergo G3s) I'm in a fairly sporty stance (I'm 6' with reasonably long legs), but it does have a telescopic stem if you want higher. The addition of something like an adjustable stem unit would be easy if you wanted to place bars further forward and enhance stability. Only thing is it's limited... I'm not sure if it can be de-restricted. It serves me well on my commute in London (9 miles, Ealing to Soho) and rides very well, certainly better (read more stable) than the Dahon Vitesse I had beforehand. If you could up the speed on it a bit, I reckon it would be perfect (mine has the 52 chainring option).

 

[Woosh]

Is the gear sensor retrofittable to your older bikes ?

it is possible to do this in Southend but very fiddly to do this at home. You need to change the gear shifter cable, then run a cable from the sensor to the second brake sensor input inside the controller box.

 

[Deleted member 4366]

Q100C looks pretty light @ 2kg, thats what I was hoping for. Do the controllers / PAS LCD setting vary the voltage so say a PAS of 3/5 would keep the top speed down when that is appropriate?

I guess this is old hat to you but I'm a newb.. can you be a bit more specific about which controller, what to look for/how/why ? Is there a really good "primer" I can read? Something with quick connectors rather than lots of soldering..as there is a huge amount of stuff on those chinese sites and very difficult to find your way as a newb.
is any of this stuff available from uk suppliers ?

insat = bga-reworking.co.uk right? am I right that they will custom build battery to whatever size/spec you want? I do prefer the idea of front bag, don't think under-seat will work nicely on a folder - need the upper part of the post for lights, and lower part needs to be able to drop for travel.

thanks

The S06S controller has 5 levels of power from the PAS. You can set it to use speed control for those 5 levels or use the default power control. The throttle can be used independently and regulates the speed to whatever you want, like a motorbike.

There's nearly always something you have to solder with any kit, especially if you want to make the wires the right length for your bike, though if you use a bag, you can hide spare wire in there.

If you're going to use a bag on the front for the battery, you might as well get a ready-made block shaped one from Aliexpress or Ebay.

 

[sandyman44]

well , after a lot more pondering and reading around, I wouldn't feel comfortable putting together the bits from china for a 48v hub motor kit, getting into overvolting on the first go at converting. I have concerns about fitting - the folder frames I am looking at are 130mm rear hub, seems this will need "stretching" which is not something I would want to do on a brand new frame never having done before. if I buy a uk sold 36v for a 328rpm motor in 20" wheel would stop pushing at 18-19 mph, which is when I want it to keep helping.. and last but not least i would really prefer discs, which is hard work with a hub (rotor size change, new/move calipers.. practically rebuilding the bike).

so I am now thinking if i use a crank drive, I can tune the gearing to suit my desired speed, and I am free to pick a frame with disc brakes no issue. 52t rings seems to be available now as standard in some of the 36v kits which is there or thereabouts. then means I can buy a 36v crank drive kit from one of the uk suppliers, safer option. 250-300w from the motor plus 50-100 from my legs at 20mph in semi-aero position is about right.

so what's the smallest lightest crank drive kit?
all I need to worry about on making it fit is bottom bracket, right?

 

[anotherkiwi]

If I could I would run with just one brake, the front one, but it isn't legal here - on brake per wheel. One hydraulic front rim brake would be my choice for weight saving.

Tern have bikes with 135 mm dropouts.