Electric2011 Dahon Jetstream P8

[morphix]

Rther than mess about with reed switches and brackets, if I did it again I'd use those "hidden wire" brake switches that you can buy alongside your kit. As far as I can figure out figure out, these brake switches have three wires (5v 0v, signal). You can pick up the 5v supply from the throttle or PAS, and then you connect the signal to the "high voltage" beake switch wire, which is a single wire in a double connector on the controller. Unfortunately, I forgot to order these switches with my last controllers otherwise I would've already tested it, but it looks like this guy has already done it - scroll down to number 13 for a schematic.
KU63 motor controller
HWBS - Hidden Wire Brake Sensor 1pcs - BMSBATTERY

I've seen those slim inline brake switch things and put them on my "to buy" list..but this raises a question..

On my old kit installed on my 26" bike there's no brake cut out, the kit states it doesn't need any as the motor cuts out instantly (in less than a second) when you release the throttle or stop pedalling.. is that the case with most kits and the cut out is just an extra safety precaution for people who might brake but continue pedalling... or could my kit be unique in this respect?

 

[muckymits]

On my old kit installed on my 26" bike there's no brake cut out, the kit states it doesn't need any as the motor cuts out instantly (in less than a second) when you release the throttle or stop pedalling.. is that the case with most kits and the cut out is just an extra safety precaution for people who might brake but continue pedalling... or could my kit be unique in this respect?

but I've seen a throttle break inside and stick on half power, also 1 second can still be a long time in an emergency

 

[Old_Dave]

Throttles have been known to fail .. having cut outs on the brakes can save an embarrassment

Unless of course you want to fit a high power kit & lock the front wheel up for doing doughnuts

 

[Deleted member 4366]

I've broken two throttles and they both stayed on. When I made my double throttles, I did some tests, which showed that the low throttle magnet has to be hard against the hall sensor for zero throttle. If you take away all magnets you get half throttle. I broke both throttles by hitting a bump (pothole) while holding full throttle. The plastic stops are very thin and easily ripped apart.

The next thin is the stopping within one second. That's an awfully long time in an emergency.

If you try and hold a motor with the brakes, it'll smoke very quickly.

 

[morphix]

I've broken two throttles and they both stayed on. When I made my double throttles, I did some tests, which showed that the low throttle magnet has to be hard against the hall sensor for zero throttle. If you take away all magnets you get half throttle. I broke both throttles by hitting a bump (pothole) while holding full throttle. The plastic stops are very thin and easily ripped apart.

The next thin is the stopping within one second. That's an awfully long time in an emergency.

If you try and hold a motor with the brakes, it'll smoke very quickly.

I guess it's a wise safety precaution then! We're fortunate that law on ebike's is quite relaxed...as far as I know there's no specific legislation which states you need brake cut outs (someone correct me if I'm wrong here)...but I will definitely fit something now based on these comments...the throttle failing is something I never even considered. That seller I got this kit from in Austria could find himself sued if someone had an accident.

I guess if you have speedict you could disable the throttle that way directly on the controller, but that would not be any help if you're doing 20mph!! No replacement for an instant brake cut-out ;-)

 

[Old_Dave]

EN15194 applies according to Wisper Bikes

Electric bikes and the Law

[h=2]brakes[/h]​

The power to the motor must be cut automatically when the brakes are applied if the bike is fitted with an independent throttle.​

But that only applies if you are taking any notice of EN15194 and not relying on the UK Electrically Assisted Pedal Cycle Regulations 1983.

 

[cwah]

In my quest of having a more comfy ride, I haven't found my DH bike for good price, but I've managed to get a Dahon jetstream for 380GBP delivered:

I'd like to have a lightweight powerful motor able to give me 30mph. I'm thinking of the BPM overvolted to 72V:
Bafang BPM 36V500W Rear Driving E-Bike Hub Motor - BMSBATTERY

Other options would be the Ezee V3 but it seems out of my price range. The Magic Pie 3 seems would have been interesting but it doesn't seem as torquy as the BPM.

There is also this new double speed motor:
New Double-speed Motor - Suzhou Xiongda Motor Co., Ltd.

I contacted the manufacturer but it seems this 3kg motor might have trouble to put some amps to it. I'm trying to see if I only have 25mph constant if this motor can make it. But I need at least as good torque as the BPM.

I think all these motors are 135mm dropout.

Any thought?

 

[Deleted member 4366]

What about a 500w Bafang BBS01 or the 750w one. They'll be a very easy installation. Seewhat your maximum pedal speed is down-hill, and that should give you some idea of the size of the crank sprocket you need. It should be easy enough to graft one on to the BBS01.

The GNG Gen 2 is another option. It's easy to graft a bigger crank sprocket onto one of those because I've done it. You can over-volt it to get it to spin faster, which is OK if you don't want to pedal, or you can also get a bigger motor sprocket from them to spin the crank faster, so you don't need such a high voltage.

The biggest problem is how to mount the battery. The best place would be on top of the frame using the bottle fixings plus some straps. A bottle battery fits there nicely with some spacers, but the most powerful one you can get is 18 amps continuous, 30 amps burst 11.6aH. You could mount a bottle battery on the frame and a frog battery behind the seat, and join them in series for 60v, which will make the high speed BPM spin to 30mph in a 20" wheel.

The frame at the back is very stiff. I could just about squeeze a Q100 in, which is supposed to be 134mm, so be careful that your motor isn't too much wider. You can't stretch the frame like you did on the Brompton.

 

[cwah]

I don't mind for any crank drive. I need acceleration and 30mph. Acceleration a little higher than my Mac 8T at 2000W on my brompton would be good.

Something that would allow me to wheelie lol. My mac didn't have enough torque for that.

I'm thinking to put the battery on the bottom of the bike, it's much more stealthy and provide more stability with lower gravity. Here is an example with controller and battery on the bottom:

Not sure yet how the battery will fit with the crank drive but without crank drive I should be able to fit about 100 sony U18650V3 cells on the bottom.


Where can I find the BBS01 750W or GNG (whatever is better for accélération)

 

[patpatbut]

Hi cwah,

Greenbikekit has 750w BBS01

Bafang/8fun/bafun 48v 750w mid crank driving kit for electric bicycle conversion-Greenbikekit.com online store for electric bicycle components-GreenBikeKit.com

p.s. how are you getting on with your MAC?

Pat

 

[Deleted member 4366]

You can wheely a crank drive in first gear dead easily. On my GNG Gen1 it's difficult to stop it from wheelying in the first two gears, si I normally use a higher gear to start. Once you're past 3rd gear, there's not so much torque. Each time you change up, it gets less. I'm not sure about the torque from the 750w BBS01. I tried one in China that they said was 750w, but it didn't seem very powerful compared with the GNGs. It's probable that they've changed something now, so could be OK. I think its 25 amps at 48v now. The one I tried had a 48v bottle battery, so 20 amps max. I run my GNG Gen 2 with 30 amps at 36v and the Gen 1 with 22 amps at 48v (12S).

Crank drives are not so good for acceleration because you have to stop the power each time you change gear like on a motorbike, so a BPM at 60v and 30 amps would be a beast. Nice and cheap too.

You need to upgrade your brakes. I'd put a hydraulic disc on the back and as wide a tyre as will fit.

I forgot that you have cells to make your own battery.

 

[cwah]

Hi cwah,

Greenbikekit has 750w BBS01

Bafang/8fun/bafun 48v 750w mid crank driving kit for electric bicycle conversion-Greenbikekit.com online store for electric bicycle components-GreenBikeKit.com

p.s. how are you getting on with your MAC?

Pat

Hello Pat,

I need to find an 8" puller but can't find one that ship to france for a decent price. I think i gave problem with the hall sensors :/

 

[cwah]

Dave, that was what I thought for crank drive. They're probably not the best for city riding. I'd get crazy to change gears before and after every red light lol.

I was thinking of the bpm or maybe the new double speed motor. Have you look at it?

And how can I add hydraulic disk brake to the jetstream?

 

[Deleted member 4366]

That two-speed motor doesn't look big enough to give enough power for 30 mph.

To add a disk brake: buy the disk brake and lever; buy a 140 to 180mm adaptor; buy a 180mm disk; remove old lever and cables; slide new lever onto the handlebar and fix with clamp-screw; screw the disk to the BPM; screw the disk caliper and adaptor to the rear fixing point. Simples!

Shimano Disc Brake Adaptors for Post And IS Mount Calipers | eBay

High Quality Mountain Bike Disc Brake Rotors, 160mm, 180mm, 203mm, incl bolts | eBay

Avid Juicy 3 Hydraulic Disc Brake Rear - used new pads and disc | eBay

Sometimes you can get the whole set together if you're lucky.

 

[cwah]

Thanks Dave. I'm going to buy all these part.

For BMSBattery purchase, what about this one at 328 RPM
Bafang BPM 36V500W Rear Driving E-Bike Hub Motor - BMSBATTERY

Then 20" 379mm rim:
Double Wall Aluminum Alloy Rim - BMSBATTERY

And these spokes?
1 pcs 13G Stainless Steel Spoke with a Brass Nipple - BMSBATTERY

Not sure how to calculate the spokes length?

And can I reuse my dahon jetstream freewheel? Or do I need to buy a new one?

Thanks

 

[Deleted member 4366]

Why not this one that's ready-built and a bit cheaper?

Bafang BPM 36V500W Rear Driving E-Bike Motor Wheel - BMSBATTERY

The Jetstream has cassette gears, so they don't fit the BPM. You need to ask Cyclezee for a 11T free-wheel. I have a 7 speed on mine, which works with the 8 speed changer system except, obviously, I have one redundant position on the changer. I'm not sure if there's enough room for the 8 speed. You should ask them to check the heights of each. They may be the same. You have 35mm space for it for a width of 134mm, so a stack-height of 40mm will make the overall width 139mm, which is about the maximum you'll get in the frame.

You should order a left-hand throttle and at least one of those hidden wire brake sensors too.

 

[cwah]

Thanks I'm going to do that.

I've seen they are also selling freewheel. Can't I use this one?
14-28 Teeth Freewheel - BMSBATTERY

And use this 180mm disc?
One Bicycle Disc Brake - BMSBATTERY

 

[Deleted member 4366]

The disk is OK, but the caliper is side-mount, so you have to find the right adapter. I think this is the one:
+20mm Disc Rotor Adaptor IS to IS 180mm 7In Hope Magura | eBay

14T top gear will mean that you'll be pedalling rather fast at 30 mph = a cadence of 120. With 11T one, the cadence would be 90, which is fast, but manageable for a fit guy like you.

 

[cwah]

Thanks for all Dave.

Going to order now.

Hope it's not going to take a month to arrive!

 

[Deleted member 4366]

I've still got my Jetsteam and I use it a lot for shopping etc. It was my birthday recently, so I decided to treat myself to some new motors. The Q100 now comes in cassette version, so I thought I would try one to put the original 8 speed cassette back to replace the 7 speed DNP free-wheel set. I was thinking of changing to a bottle battery with integral controller, but when it arrived, I looked inside to find a sealed controller, so I'd be stuck with 15 amps. I prefer it with 17 or 18 amps. I'll have to think for a bit.

Here's the motor:



I built it into a Mavic rim that I had lying around, which looks identical to the BMSBattery rims. I used BMSBattery 13g x 145mm spokes in a one-cross pattern. It needed a bit of dishing to get the rim central. I would say that it's about 140mm wide, but it should squeeze in.



Nice and stealthy. Even more so when I fit a disc brake. I'm fed up with the crappy rim brakes: