Dahon D7 Vitesse Conversion

[kouchris]

hello all,
My nane is chris and i live in Athens, Greece.
This is my frist thread to this forum after doing a lot of reading, i gotta say that this forum is more than amazing and the people posting in here are very passionate and take things a step further than the average cyclist forum.

I own a Dahon Vitesse D7 and i am interested in converting it to an electric one following the DIY route.
There are 3 reasons that i want to do this following the DIY route
1.The main reason that i want to follow this route is because i want to undrestand how it works so that i will be able to repair it myself.
2.Another reason is the money. I cant spend to much cash to buy a kit that includes everything.
3.Last but not least The feeling that i did it myself
I have been searching the forums and the internet for some weeks now and i cant seem to find someone that has converted a dahon following the DIY route. Many thanks to Daniel and jerry for their posts, i have spent a lot of time reading their them and their links to sites that have helped me understand many things concerning electric bikes and the DYI route.

The one site that has converted a dahon D7 is this:
Dahon Vitesse D7 Electric
This is something that i would love to do.It looks really neat and there are no cables or bags hanging out.

Anyone tryied to convert one of those ?
Any suggestions on what i should be looking at?
Any help would be more that great!

Chris

 

[kouchris]

bafang 350w BPM

I came across this motor..Looks like it can take a 7-speed cassette and 350w would be more than enough to take me up on every hill..
I gotta say 4 kg is much tho
What do you think about it?

Chris

 

[Deleted member 4366]

The kit in the first photo looks a lot like a Sunlova kit - certainly the same motor (Bafang 250w), rack and battery. I have fitted one of these kits to a mountain bike. I'm unfit and 110kg and I find a 250w motor adequate for my needs. I only struggle on very steep hills. The things you have to look out for is;
- Having enough room between the pedal and bottom bracket for the pedal sensor. You might need a longer spindle.
- If you have twist-grip gear change, you must think about how to install a throttle (left or right hand)
- not a problem for you, but some bikes have the brake levers integrated into the gear-changes. These mean you can't install the ones with the necessary brake power cut-off switches
- if you have a disk brake, it needs to be at least 180mm otherwise the caliper will rub on the motor. Smaller disks can easily be upgraded by buying a spacer and larger disk.
- The Sunlova pedal sensor doesn't appear to be waterproof, so I would recommend dismantling and sealing it with silicon sealant.

All the above problems are from my own experience, and when you know about them are easy to overcome, so don't let that put you off. I think that the Sunlova kit represents good value, when you get it sorted. I'm sure other kits have similar and different problems.

 

[Trevor Holloway]

- Having enough room between the pedal and bottom bracket for the pedal sensor. You might need a longer spindle.
- If you have twist-grip gear change, you must think about how to install a throttle (left or right hand)

There was a plastic cover on the pedal sensor which once removed allows another 4-5mm clearance - its still a bit tight and the two halves rub together - may be able to reduce this with some "wet & dry paper", something to check when putting the silicon sealer in.
I requested a thumb throttle with my Sunlova kit - which gets round the twist gear change problem.

Now getting close to 500 miles on it and am very pleased with how it performs.

 

[kouchris]

Thanks very much for the reply.

I find a 250w motor adequate for my needs. I only struggle on very steep hills.

I was thinking that 250 might not be enough but i weight less than you do so i dont think i ll have problem with climbing. What worries me and im not sure about is that you have installed this kit to a mountain bike and means that you probably have bigger wheels than the dahon(20"). As a result i ll be having less RPM(?) and better torque(?).Does torque have to do with wheel size? (That can probably be found on other topics but im writting this so..)
Is that Right?

The 350w Bafang BPM i posted is named high speed motor. does that mean that it goes better on flat ground mostly? I d rather go for climbing abilities than speed.

The sunlova kit is a front wheel hub motor. I was hoping i d find something that i can install on the rear wheel. I d love to try finding the parts one by one and buid it step by step.
Hoping its not muuuch more complicated as a build(The rear wheel route i mean)
@Trevor. what kind of bike do you have the kit installed?
Thanks again for the replies they were really helpful.
PS: Thats a pretty smart quote on your messages d8veh

 

[kouchris]

- Having enough room between the pedal and bottom bracket for the pedal sensor. You might need a longer spindle.

i'm posting an image of the pedal build below

The other side

I think i ll have to do some work on this cause there is no space in between..

 

[jbond]

The 350w Bafang BPM i posted is named high speed motor. does that mean that it goes better on flat ground mostly? I d rather go for climbing abilities than speed.

The BPM comes in a number of "codes" that reflect the motor wind and gearing and hence the top speed and torque available. Detail here.
Endless-sphere.com • View topic - Bafang BPM Pics and Specs - Large 3.9Kg Sensorless Geared
The one fitted to the Alien Aurora is a Code 11 for a 26" wheel marked up as 36V350W 26(11) That gives about 21mph top speed and serious hill climbing. It's a very good compromise. The specs in the link show a code 10 with a bit more no-load rpm and there may be a code 9 as well with even more no load rpm.

So who knows what "high speed motor" actually means without knowing the actual product type numbers.

 

[mechaniker]

So who knows what "high speed motor" actually means without knowing the actual product type numbers.

"high-speed-motor" means the internal speed of the motor. The higher internal speed follows a higher rpm-reduction in the planetary gearbox.
the SWXK or SWXH or SWXB work with 4,3 rpm reduction and the BPM with 4,9 rpm reduction.
That´s what "high-speed-motor" means.
now the real high speed motor from bafang is the SWXU with 5,2 rpm-reduction

If somebody would like to see the Bafang Motors from inside, i can put on my website, just tell me wich motor internal photo i should put on there.


"kouchris"
you can fix the magnets from your pas to the sprocket and for the pas-sensor is enough space on the crankbearing

have a good day
frank

 

[Deleted member 4366]

Kouchris: When you buy a kit, you only have to tell them what size wheel you have and whether you want front or rear wheel drive and they will send you the right one. If you check out the Sulova.com website, you can see the different kits. It looks like you don't have enough room for the pedal sensor unless you change the bottom bracket spindle, which is quite straight forward. I took the opportunity to upgrade mine to cartridge type by fitting this one, which I can confirm allows the standard RHS sensor to be fitted:
131mm KINEX SEALED BEARING BOTTOM BRACKET 31L132 on eBay (end time 17-Dec-10 10:31:36 GMT)

 

[kouchris]

The one fitted to the Alien Aurora is a Code 11 for a 26" wheel marked up as 36V350W 26(11) That gives about 21mph top speed and serious hill climbing. It's a very good compromise. The specs in the link show a code 10 with a bit more no-load rpm and there may be a code 9 as well with even more no load rpm.

I guess that those performances are refering to a motor fitted in a 26 wheel. Will the difference be a lot when i build it on a 20" wheel?
As i said top speed is the top speed is not the primary target in my case. i want the morot to be able to help me on hills. I am also worried about the weight on that motor. The bike is a folder so i would like it to be as light as it can be.. i ve seen that jerry and dave have chosen the light versions of the tongxin and the bafan motors.
Would you recomend me to choose one of those?
I will be pedaling as well, its not that i want the motor to do all the work for me. What i am concerned about is getting a motor and after building it in find out that it doesnt have what it takes to help me commute.
is there a motor(preferably rear motor) that any of the members recomends for my needs?

 

[kouchris]

I took the opportunity to upgrade mine to cartridge type by fitting this one, which I can confirm allows the standard RHS sensor to be fitted:
131mm KINEX SEALED BEARING BOTTOM BRACKET 31L132 on eBay (end time 17-Dec-10 10:31:36 GMT)

That looks pretty good. Thanks so much for the information d8veh. Im pretty sure i ll be needing one of those

 

[kouchris]

"high-speed-motor" means the internal speed of the motor. The higher internal speed follows a higher rpm-reduction in the planetary gearbox.
the SWXK or SWXH or SWXB work with 4,3 rpm reduction and the BPM with 4,9 rpm reduction.
That´s what "high-speed-motor" means.
now the real high speed motor from bafang is the SWXU with 5,2 rpm-reduction

Im confused.:S
So from what i understand this can means that high internal RPM leads to an reduction in the wheel spinning?
So the High speed motor refers to the internal RPM?
if so, is that good for the torque?
not sure if my questions make sense i hope im not frustrating some with my noobish questions..i would appriciate someone sending me liks to read abot motors and electric bikes. An e-book would be greaaaat
PS : could some one show me how to use mutli quotes ?)

 

[jbond]

I guess that those performances are refering to a motor fitted in a 26 wheel. Will the difference be a lot when i build it on a 20" wheel?
As i said top speed is the top speed is not the primary target in my case. i want the morot to be able to help me on hills. I am also worried about the weight on that motor. The bike is a folder so i would like it to be as light as it can be.. i ve seen that jerry and dave have chosen the light versions of the tongxin and the bafan motors.

The Bafang BPM is a big old heavy motor. It's good for what it is, but it's probably overkill for a folder. The specs tend to be in terms of no-load rpm which is a little above the maximum speed. As speed increases, there comes a point where torque drops off and this is the point where the torque just equals the drag. The speeds I quoted were for a code 11 mounted in a 26" wheel. For a 20" wheel you'd need more rpm for the same speed.

I think you'd be better looking for small motors such as the Bafang QSXK/H (front/rear), the Cute 85SX or 100SX or a Tongxin. There are several threads here about people converting Bromptons with the Bafang and Tonxin motors.

 

[Deleted member 4366]

Kouchris: As I said before, you don't have to worry about motor speeds, torques and designations. You only have to order one for a 20" wheel and the supplier will give you the correct one optimised for you application.

The way I see it is that you only need to decide whether you want front or rear wheel motor and 250 or 350 watts.

There's been previous discussion in this forum about what's best regarding front or rear and the consensus seemed to recommend front as the best, but that didn't take into account the need to fold your bike. If you fold frequently, there might be some advantage in a rear wheel drive, but it'll be a bit harder to remove the wheel to fix punctures etc because of the power cable.

250 watts is legal 350 isn't. If you are involved in an accident, you run the risk of being prosecuted for no tax and insurance with 350, otherwise I don't think there's too much risk of getting found out.

If you decide on the 350 watt kit, you can get it from here with the motor already built into a wheel:
Bafang 350Watts/500Watts BPM Motor E-Bike Kit [Kit-BPM] - $179.00 : BMSBATTERY!, The Art of Battery
You must click the "Attributes" tab to select wheel size etc. Without a battery, it's about £200 inc postage. You probably won't have to pay duty. If you want the 250 watt kit, you would be better to get it from Sunlova because a 9ah battery is included and there is no risk of getting caught for duty. Or you might try one of these that looks very similar to a Sunlova kit. Perhaps they come from the same source:
36v 250w Rack mounted Electric bike conversion kit for 20 inch wheel bicycle at Online buybuybicycles.com

 

[mechaniker]

I agree that the BPM is a little bit oversized for a folder.
I would use a swxh for the rear or other small motor´s for the front, the freewheel of the BPM is also not relly good. The BPM is build to climb mountain in a 26" wheel. If you have a 20"wheel, you dont need this kind of motor.
The BPM is not old because this motor is around 2years on market and for what he should doe, climbing mountain, it is a good motor.

In a 20" folder, a small 250Watt motor have enough power to climb the mountain, my opinion.
I would choose a SWXH for the rear or a SWXU or an SWXK for the front. But unfortunatly most time the front fork of dahon-bikes is only 80mm so you must change the fork into a 100mm fork because Bafang or xinfeng dont build 80mm motors
I dont like cute Motor but it is a bit better as a tongxin or a weifeng 80mm Motor.

frank

 

[jbond]

the freewheel of the BPM is also not relly good.

It's the only Bafang I've tried but the freewheel feels fine to me. The wheel spins down less fast than my Hybrid rear with the same Shimano gearset but the drag is otherwise imperceptible.

I dont like cute Motor but it is a bit better as a tongxin or a weifeng 80mm Motor.

Any particular reason you don't like the Cute motors? The specs seem very similar to the small Bafang motors but lighter.

 

[Trevor Holloway]

@Trevor. what kind of bike do you have the kit installed?QUOTE]

Its the other end of the scale - a 28" wheeled Peugoet Hybrid.

 

[rooel]

Back to your original question, Kouchris: does the Dahon D7 Vitesse not have an aluminium frame? If you go for a front wheel drive, as I have done with steel frame Speed TRs, you will require a motor width of 75mm. These are available but most are 100mm. As the front forks on the D7 Vitesse are aluminium it is not possible to widen them as I and others have done with the front forks on steel Dahons (eg Speed TR and D7, but not D7 Vitesse). It may be possible however to obtain a spare Dahon steel fork from CH Whites of Malborough (the same company as foldingbikes.biz).

 

[kouchris]

Sorry for being away for so long.

The past week has been a little crazy and i didnt find the chance to post a reply giving the appropriate attention.
I would have to agree with all of you sugesting that the BPM is an overkill for a folder. After some searching on the web i decided i will go with the SWXH unless someone has something better to suggest and then i would have to reconsider.
Concerning the SWXH there are some things that worry me.
1. The Bafang site rates this as a 220w Maximum so i guess that it is less powerful than a 250. Since many people recomends this i guess that i has what it takes.(?)
2. Bafang says that it will fit a 6-speed Cassette. My dahon has 7. Any help here?
3. Bafang mentions shaft length of motor:192mm. Does that mean that the distance of the iron rod(not sure what the name is) that goes from the one side of the fork to the other has to be 192mm?if so then what is the firk size:136mm?(and that has to do with the question no2).If i am to use a 7speed cassette, how? if a am not i would have to get a new gear control that is for 6 speeds?
4. 24 or 36 volts? i havent seen anyone using 24 volts. From what i get 36 wolts means more power to the motor(?)
5. Anybody knows a place to buy these(safely)? I should probably contact bafang. Thing is that i would prefer ordering for inside the EU so that i dont have customs to face. Anyone knows the price for this set?(including controller Ect.) What will the difference be between the price i ll get from bafang directly and the price i ll get inside the EU?(i ll search these myself too but if someone has already done it, maybe he can point things out for me.)

Thank you so much for the help you have already given me.
Chris.