Single-speed track stealth ultralight

[zro-1]

Hello ES peeps,

I'm beginning my next ebike build. As reference, my first build is a FS Motobecane with a BBSHD and a plastic "shark" pack mounted on the downtube. It's a beast, both in looks and in power. I built it clean without any wires dangling around, but there's no fooling anyone that it's an ebike. This time I'm going in the completely opposite direction.

This time I'm using an ultralight aluminum single-speed track style frame, and I'm using a Q100H with a Phaserunner controller. I'm also building a 14s2p pack using LG MJ1 3500 mAh 18650 battery cells. So, I'll have 51.8V 7Ah with 20A discharge available to power this thing. I'll probably only put 11-15A out to the motor to start. I do have a couple hills that can be challenging, so I'll need to test the bike to see if I need to put a few more amps into the motor or not. The battery will be contained in a seat bag behind the seat and I'll be running the wires inside the seat tube to exit just above the bottom bracket shell in the rear.

I'm taking this build slow so there won't be a mad flood of updates to this thread all at once, but I'll post new images as I make progress.

Here's the bike I'm using as a base:

The bike in stock form comes in at about 18 lbs (8.16 Kg). I don't have a specific weight goal other than "as light as possible while meeting my needs".

I got the Q100H already, so I decided to do a test fit. This frame has only 120mm dropouts, so I decided to remove the nut and one of the spacers on the drive side of the shaft. I knew I could flex the dropouts to fit the motor with just the 2 spacers and no nut, but I wanted to get the drive side as close to the dropout as possible since I'm only using single-speed. This actually worked out really well, because shifting the motor over by removing the spacer ended up mostly centering the motor in the dropouts and is going to give me a nice straight chainline for the single-speed.

EDIT: I took some measurements, and the motor is shifted towards the drive side by 4.5mm. This should be a very easy dish. Time to go plug the numbers in to the spoke calculator over on ebikes.ca

Here's what the motor looks like in the frame:

Here's the centering of the motor in the dropouts:

I think this photo makes it look a little more offset then it actually is. I need to take some measurements to know for sure. I'm OK with a little dishing as long as it's not too much.

Here's the chainline using a straightedge pressed against the inside of the chainring:

I need to pick up some washers to fill the gap between the remaining spacer and the drive-side dropout:

Over on the brake side of the motor, I'm thinking about removing this side of the shaft and drilling a hole to run the wire out between the case and the dropout. I'm using rim brakes so I don't need to worry about clearing a rotor or anything.
Here's the gap I have to work with if I decide to go this route:

Do you guys think this might weaken the axle too much? I could live with the shaft-end exit, but if it didn't risk integrity, I'd love to hide the wire even better (and protect it) by keeping the wire inside the dropout.

That's about all I have to show so far. I'll update the thread as I do more work.

 

[zro-1]

Hmmm. The images won't load here. They load just fine if you right-click on the [?] and choose to open the image in a new tab... I wonder if its something with dropbox...

EDIT: I moved the pics above over to my website and now they load as expected.

 

[zro-1]

This may be useful to the rest of the forum: I was able to decipher the info printed on the motor casing. Here's what the motor reads:

AKM17062901002
AAD3620A
H

AKM = the manufacturer, Akiema (or however that's spelled)
170629 = the date of manufacture (2017-06-29)
01002 = The motor model and version (0100 = Q100, 2 = version 2)

AAD = I haven't been able to figure that out yet, but I believe it is the code for the style of gears/brakes the motor can use (freewheel + disk/rim brake)
36 = 36 volts (yeah, I'll follow that :wink: )
20A = 20 amps
H = the H-series of the Q100

 

[zro-1]

Dang. I was hoping a 4.5 mm offset wouldn't be such a big deal. The spoke calculator seems to show a pretty big change in spoke tension though...

Maybe I should consider letting the chainline be a bit off to get the motor better centered.

EDIT: Problem solved. I can just flip the orientation of the left spokes to get a better tension balance.

 

[zro-1]

I got my batteries and BMS today, so I decided to hot glue them together and see how they fit in the seat bag I have. This will be a 14s2p pack

51.8 nominal volts
7 Ah
20 A discharge
364 nominal Wh

This is the batteries glued into 3 groups 2 batteries wide, which will be easier to spot weld.

These are the three groups.

Here's the bag the pack is going in to

The pack fits really nice with just enough breathing room for the BMS and wires. LOL ignore all the notes I'd scribbled all on the margins of that paper it was just stuff I was thinking about as I was researching.

This next drawing is to show how the cells will be connected

 

[zro-1]

I ordered a Boss Welder from ES member Aulakiria yesterday. Since his welder uses a remote probe I won't have to worry about squeezing a bunch of batteries under the attached probes of the 709A welder I was thinking of getting. So, I'll be gluing the parts of the pack together ahead of time to get it ready for welding. I'm excited to be building my own pack for the first time.

 

[chas58]

Nice – that is the bike I built in 2013. It is so much fun riding a fast light ebike (and super rare). I have a mountain bike version too, but I don’t use that much. Light and fast is my passion!

Where did you buy the motor from? What rpm version is it?

FYI, I went to the hardware store and found some nylon washers (in the nuts/bolts section) and just cut that down to the size I needed to make it fit the 120mm drop out. Chainline was perfect, and I don’t remember the wheel requiring much dishing. Gotta love single speed!

I like where you are going with this. I may have to order some of those battery packs from you.
(see the thread in my sig. Bike is about 29lbs with battery and 25mile range (at 25mph)).

 

[chas58]

Here is my light weight speedster. The frame bag holds the battery, but it is mostly empty (or available for other cargo). I've cleaned up the wiring a little since this shot.

 

[zro-1]

I actually looked at your build thread (EDIT: not your build thread, but I have check that bike out on here at a couple of points) chas58 when I was researching which hub motor I wanted to go with. I really like your build. I almost chose a similar bag to what you have. I've got a 14s4p that still has some good Ah left in it and I was going to use that and toss it in the frame bag, but it just wasn't stealthy enough for what I want to do with this build.

I got the motor from BMSbattery. It's the 260 rpm Q100H. From some of the older Q100* threads I read through, I think this motor should have .35mm laminations as opposed to the older ones that had .5mm. That combined with a FOC Phaserunner I think should give nice efficiency for the small size. Do you know what sort of Wh's you consume on your ride? When I was doing some back-of-hand calculations to see what sort of range I may get, I was using 25Wh/mile but I honestly don't know what to expect with such a light build as this.

 

[zro-1]

By the way, this is my FS MTB build that's my current daily ride. It's nice, but I just want something lighter, cleaner, and that looks more like a non-electric bike.

 

[eCue]

zro-1 I like those mid drives, it appears to me your bike is fairly stealthy as is you could carry the battery in a day pack it stands out as much or more then the motor.

Im feeling like being stealthy as well, my kit is on order have a front 350w black hub motor and 12AH of batteries that I will carry in a day pack with the controller.
I have been reading keeping it warm will extend its winter range by 20%

According to a online chart 75* to 80*f is the sweet spot for retaining max battery AH's

 

[zro-1]

I've considered placing the battery in a pack, but the trouble is that I use this bike as my daily commuter, so I'm already lugging a laptop and lunch along with some small tools and a spare tube in my pack as it is. That's not counting the days that its raining and I need a change of clothes or rain gear. Then there's the fall where its jacket cold in the morning and t-shirt warm in the afternoon, so I end up packing spare clothes. I don't want that much weight on my back every day.

With a small seat bag pack, it won't look like a battery, and it'll keep the weight off my back & shoulders.

 

[eCue]

I'm thinking that the seat post would be a good spot for me for summer.
If I can mount the battery somehow , it appears it would be the best place to balance the front / rear weight distributions with both a front wheel and mid motor set up.

Its important to the ride quality or quality of ride and something I planned to tweak. As it is for winter the backpack is my best option and its not noticeable weight for me. I carry a daypack to the grocery store and hardly notice 30lbs on the back , it doesn't slow me down.
A pack battery will cut into cargo space though but it will fit where the camel bac bladder slides in so its fairly unobtrusive

 

[chas58]

I have a seatpost battery for one of my builds. with my 3lb battery it works. I wouldn't want too much weight that high.

How do you attach the power feed to the backpack?

I saw one design once that used magnetic coupling effectively acting as a quick disconnect to the power supply. I did do the backpack thing once, but the cord just seemed like such a hassle...

 

[PRW]

I did this, using a Luna mighty mini and a seat bag - but I don't think it is the right solution for running +-1500W (Mac 10T). I will probably change to something else (bottle battery/ shark) at some stage.

 

[chas58]

I love the mighty mini.

Long before they came out with that, I asked them if they would make me one in 36v format. At the time they were not interested in 36v packs, so I had em3ev make me one (same size and watt hours, but much more Ah). I'm glad they took the idea and ran with it (at least in a 52v format). But, since they are basically the same configuration, my battery fits in their little under seat battery pack.

 

[eCue]

I need to find a durable quick connect power coupling when I get it figured out I'll try to remember to post back here.
Im thinking I might use jet ski kill switch with lanyard and zip tie the power cable to it with a disconnect near the kill switch

 

[zro-1]

Yeah, the mighty mini is pretty sweet. I'm basically building a mighty mini (14s2p) but custom shaped to fit my bag instead of square.

 

[zro-1]

eCue: Micha from ebikeschool.com did a video on those magnetic connectors
[youtube]cxXKvG3Y9-0[/youtube]

If I ever did do a backpack battery, I'd definitely use a magnetic connector.

 

[eCue]

Thats the Gizmo I need , will do some online searching and and pick one up.

thanks for the post , it is the ticket alright

 

[zro-1]

I finally have some time and money to continue work on my bike, but I've hit a major snag and I need some help.

I started lacing my q100 into my rim, and I noticed that the spoke holes on the flanges are directly across from each other instead of being offset. You can see what I mean here when you look at the right side flange holes and the left side flange holes:



If you look where I'm pointing at here, it looks like the factory had center punched a mark on the flange to drill which would have given the offset, but then ended up drilling in a different pattern:



This is causing me a major headache in getting the wheel laced up, particularly when trying to do the leading spokes in a 2-cross pattern. This is where I've gotten to so far:


Here's the spokes at the hub flanges (I tried to line everything up):


Here's how short the last 9 leading spokes are despite muscling-around the hub and rim alignment:


I was hoping one of you with a q100 can check the flanges on your motor and tell me if the spoke holes are directly across like mine, or if they're offset from each other as you'd see on a regular (non-motor) hub. Also, any tips you may have on how you laced your q100 into your rim would be helpful at this point. I'm at my wits end in trying to figure this out.

If the holes on your flanges are directly across from each other on either flange, how do the spokes run to the rim? I'm wondering if I need to run the trailing spokes directly across from each other on both sides instead of offsetting them by one hole, but that seems in my head like it would just make matters worse and I wanted to ask here before I tear-down the wheel and start over.

 

[zro-1]

Following up to reinforce that I suspect the flange holes were drilled wrong on my motor, in this marketing pic, you can clearly see that the holes are offset on each flange

 

[eCue]

Maybe try a longer spoke ? it looks like the punch hole is the one thats out not the drill hole ?
Different Hub but on my and others Mxus xfo7 350w they use one cross only , it looks stupid buts its how they did it at the factory. It looks like the spokes are straight across the rim.

 

[Chalo]

The spoke holes must always stagger evenly. The only way to cross-spoke a hub that's drilled incorrectly as yours is, is to use mixed spoke lengths. That's a project for an advanced wheelbuilder.

You can use "radial" lacing on your hub, and because the holes aren't correctly aligned, it won't be purely radial and thus will be able to workstand torque. Add maybe a mm to whatever length you'd need for normal radial spoking.

 

[Buk___]

The spoke holes must always stagger evenly. The only way to cross-spoke a hub that's drilled incorrectly as yours is, is to use mixed spoke lengths. That's a project for an advanced wheelbuilder.

You can use "radial" lacing on your hub, and because the holes aren't correctly aligned, it won't be purely radial and thus will be able to workstand torque. Add maybe a mm to whatever length you'd need for normal radial spoking.

Doesn't this result in an even length and pull?