BBS02 Cake -- FS mid-drive build, v2

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tln
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BBS02 Cake -- FS mid-drive build, v2

Post by tln » Oct 21, 2014 8:12 pm

I revamped my previous build:

https://endless-sphere.com/forums/viewto ... =6&t=62114

I switched the brushed GNG for a BBS02 and a Calibike for 2x 6S Multistar 16000 mah.
That saved about 7lbs bringing me down to a svelte 47lbs :)

The stock chainring didnt let me use the lower gears, I picked up one of the 42T italian
chainrings from hie2kolob and so far so good!

The battery box is a Radio Shack project box slung underneath the downtube. This box
fits very nicely between the cranks, I'd really recommend it. It has to be kept straight to
avoid the cranks; there were bottle bosses on the underside on this bike so I screwed the
lid directly to the frame which keeps it perfectly lined up. Gorilla tape is also used to keep
the weight off the screws (but tape alone would probably shift too much)

No clearance issues on the front tire, even if I let the shock pressure all the way out and
jump on the front a lot. In fact I positioned it for the stock chainring and could move it down
an inch more.

If you find a good way to mount it, this battery + box under downtube + BBS02 is
a sweet combo!
IMG_20141021_165306.jpg

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Re: BBS02 Cake -- FS mid-drive build, v2

Post by 1KW » Oct 26, 2014 11:37 pm

nice build!
I've got the same battery setup, 2 x 16ah multistar. which size radio shack box did you use?

http://www.radioshack.com/family/index. ... Id=2032276

tln
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by tln » Oct 26, 2014 11:51 pm

The 8x6x3... Its like a hardcase for these lipos :)

http://www.radioshack.com/product/index ... Id=2062285

evolutiongts
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by evolutiongts » Oct 27, 2014 1:36 pm

tln wrote:I revamped my previous build:

https://endless-sphere.com/forums/viewto ... =6&t=62114

I switched the brushed GNG for a BBS02 and a Calibike for 2x 6S Multistar 16000 mah.
That saved about 7lbs bringing me down to a svelte 47lbs :)

The stock chainring didnt let me use the lower gears, I picked up one of the 42T italian
chainrings from hie2kolob and so far so good!

The battery box is a Radio Shack project box slung underneath the downtube. This box
fits very nicely between the cranks, I'd really recommend it. It has to be kept straight to
avoid the cranks; there were bottle bosses on the underside on this bike so I screwed the
lid directly to the frame which keeps it perfectly lined up. Gorilla tape is also used to keep
the weight off the screws (but tape alone would probably shift too much)

No clearance issues on the front tire, even if I let the shock pressure all the way out and
jump on the front a lot. In fact I positioned it for the stock chainring and could move it down
an inch more.

If you find a good way to mount it, this battery + box under downtube + BBS02 is
a sweet combo!
IMG_20141021_165306.jpg
What's you top speed on a flat?
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tln
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by tln » Oct 27, 2014 2:42 pm

evolutiongts wrote:What's you top speed on a flat?
Honestly I've been spending more time going up hills :)

I've hit 30mph on a short flat, with pedaling help. Thats actually just over the PAS limit (50kph).

Its a 42 tooth front, 12S, with stock programming, and knobby tires.

I'm not really expecting much more than 30 but there should be a little more to squeeze out of
the setup

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0utrider
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by 0utrider » Oct 28, 2014 4:44 pm

tln wrote:I'm not really expecting much more than 30 but there should be a little more to squeeze out of
the setup
Yup, that's what I've been experiencing. On a flat my weight and gearing have me pegged around 30MPH. I'm going to experiment with lower gearing to see if I can reach 28-30 mph with a higher crank rpm so the motor is happier.

Anyway 30 is honestly is fast enough for my nerves on the walmart bike till I either dial in the stock brakes better or replace them with avid bb7s.

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Re: BBS02 Cake -- FS mid-drive build, v2

Post by 0utrider » Oct 28, 2014 4:45 pm

Awesome build! It has me hungry for cake!

tln
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by tln » Jun 05, 2015 1:20 pm

I figure its time to update this build. Its been running decently for the last 9 months, with mostly weekend use although I am now commuting on it 90% of the time.

The 16000mAh Multistar batteries are getting harder to balance though, and with this being a daily commuter, I started keeping an eye out for backup batts. Hard to get 16ah multistar in stock these days! and honestly don’t need it all so went for multistar 10ah batts this time.
10 on 16.jpg
Multistar, meet your little brother
10 on 16.jpg (74.8 KiB) Viewed 1317 times
I've been planning a more removable battery attachment, saw big blue saw sale and jumped on it to make a removable holder out of .25" Aluminum
holder on top of batts.jpg
Battery holder, on top of Multistar 16ah
holder on top of batts.jpg (61.1 KiB) Viewed 1317 times
While I was waiting for the part I crashed out on the trail and my old bottle-screw and strap-based system stopped holding the battery steady. I have very little room for play without the battery hitting cranks, so the battery was hitting the cranks while I limped home. it was definitely time to redo the system! In fact when I took off the battery, I saw that the screw had bent a bit...
old lid.jpg
Old battery holder system
screw bent.jpg
Doh! Bent the frame a bit around the bottle boss
screw bent.jpg (231.13 KiB) Viewed 1317 times
I decided not to use the second screw when installing my holder. Thats an M5 screw, lots of JB weld, and fiberglass repair tape. I don’t think it’ll budge now!
holder installed.jpg
Holder installed on bike with fiberglass tape and bottle boss screw
holder installed.jpg (74.87 KiB) Viewed 1317 times
Now I have a couple of changeable batteries :) I need to take a picture of how the case attached to the holder, and a video of the change out process, takes 10 seconds.

keithwins
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by keithwins » Jun 14, 2015 5:54 pm

Hey, I got here after you commented on my thread: this is a lot like the build I'm starting. Now that you've had a few months, how do you like the BBS02? That's what I'm looking at.

Keith

tln
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by tln » Jun 15, 2015 1:34 am

I love it, any hill is rideable now which is very impor ant for my neighborhood and local trails. I'm almost at 1500 miles!

There have been some annoyances, I've gone through two cranks and need another new one; and I get more chain drops and chain suck issues than I like.

It's a blast on the weekends and a fun commuter :)

Ps isn't DC pretty flat? If you have no hills then mid drive doesn't do much for you. You will have snappier acceleration from a MAC for instance

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Re: BBS02 Cake -- FS mid-drive build, v2

Post by keithwins » Jun 15, 2015 9:56 pm

Well, the MAC is interesting, I hadn't seen that. But I've figured that a hub motor would get creamed by all potholes, congressmen, etc. that I hit regularly. Though your replacement parts list with the BBSO2 is pretty concerning, I'm not looking for a project, I'm looking for an ebike...
k

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Re: BBS02 Cake -- FS mid-drive build, v2

Post by mwkeefer » Jun 16, 2015 12:34 am

Hello,

Depending on the weight and wind resistance (mostly), combined with rolling resistance (minimal in most cases) the BBS02 750 can be geared for up to 30-35 mph but even geared for 35 mph using 48v @ 25a you will only see 88% of that (efficiency) which would be roughly max road speed of 30.8.

This is for an average rider of 200 lbs and a 26 or 20" (gearing is different obviously).

If you switch to a 6FET external controller you can push 30A and 1.2 - 1.5x phase current and squeeze an extra 5 mph out of the top end so gear for 35-39 and reach and sustain 35 mph without damage.

In addition you can run 15S (don't expect to pedal along) and at 25A gear for 35 mph with the stock controller.

I prefer 118 RPM cadence at 48v on an external controller and geared for 38 mph on a 20" wheel which lets me get almost to 35 consistantly at nominal pack voltages..

In all these scenarios I have calculated the efficiency losses and confirmed the motor is performing at or near max efficiency in all gears available.

The max power I've run the BBS02 at (it got hot but not too hot to touch) was 1650w constant voltage but with an external controller only.

Hope that helps.

-Mike
Regards,
Mike

{My Rides]
2010 Dahon Jack - GNG v1 - LYEN 6FET - 20/40A - 18S2P10AH - Nom:66.6v,1332w
2004 Hard Rock Pro Disc - Recumpence ms eDrive v4 - Astro 3220 4T - 12S2P16AH - HV110 - Left Side Drive - Gearing: 38mph
Nominal Peak Power @ 60 seconds: 5328 watts - Maximum Power: 49.8v, 120A, 5872w
2010 Downtube 8FH - Stock GNG v1 Stock Controller - EB809XC - 12-16S
2012 Downtube Nova 7spd - Stock GNG v2 - 12S2P10AH - EB809 - 12S-16S - 20A/30A,Nom VCC: 44.4, 888w

tln
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Re: BBS02 Cake -- FS mid-drive build, v2

Post by tln » Jun 16, 2015 8:38 am

Mike,

That's really interesting. You are pushing the boundaries of the BBS02 system! Why do you run a 20" wheel though?

Are you actually pedaling at 118RPM cadence?

I barely hit 30mph only with a long runway (like 2 city blocks) and lots of pedaling :) Thats with 42t on the front,
12t on the back, knobby tires (not efficient!) and a fresh 12s battery.

Keith,

It should be pretty easy to avoid the issues I had. One set of crank arms got ruined when I tried to use some crappy old pedals
and frocked up the threading. After a couple of hundred miles the pedals worked themselves off the cranks. On the current left crank, I didn't torque it in sufficiently and now the taper part has widened so it wiggles a little with every stroke. Just torque the crank retaining screw in really tight and it'll be fine :) The chain ring I got was actually second hand and the seller was getting rid of it due to chain suck on his bike. Now there are more options for a 42t offset chain ring... I really should get a new one. I'm also eyeing a rear derailleur with a clutch.

Incidentally, if you get the BBS02, I'd suggest you get a spider adaptor and a 44t chain ring from bafang in additional to the stock 48t. You might need smaller gears up front because of the 29" in the rear, and the spider adaptors lets you choose anything you like. The 44t is pretty cheap and gives you another gear to try.

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