My 16" folder Mid-drive BBS02-750w build - COMPLETED

[nukezero]

Hi everyone

EDIT: SEE POST BELOW FOR BUILD

I'm doing my second build now. I just got this bike in the mail. I'm planning to electrify it with a bbs02 750w 48v 13s4p. I already have a 26" townie, Mac8T, 48v, and my gf has a 26" townie with bbs01 36v. I'll be using the downtube frame battery I made with 25R samsungs. This will allow me to share the battery between my 26" and my 16" bikes.

I wanted a folder so I can stash this in my trunk and take it out whenever, but I also know speed is my primary goal. The bafang kit is supposed to come next week.

The bike is a bit twitchy when going very slow. It was very, hard to find a 16" folder with a nexus 8 spd hub, and downtube is the only company that made it.

-52T/16T chainring/sprocket is stock - this is good because the bbs02 I got comes with a 52T as well. I won't need to add chain links. whew

My only concern now is just the chainline. I think the stock bafang chainring will give me about 8mm offset inward towards the bottom bracket.

 

[tomjasz]

I like it!

 

[tomjasz]

Progress?

 

[footloose]

Love folders, Nexus 8 hubs and BBS02.
Combo is cool.
I built up a Raleigh 20 with Nexus 8 and BBS02 last year.
Great bike.

Only issue was weight distribution related.
Folders generally have shortish wheelbase, upright riding position, hence c.o.g. pretty far to rear.
Combine that with some steep hills, and front end had a tendency to lift easily.
Once found myself riding up a hill unicycle style with front wheel off the ground. Unintentionally.

With 16" wheels versus 20" the tendency might be even more pronounced.

Have fun but be aware on first test rides!

 

[nukezero]

The motor kit is at customs lax. Expect to receive by tomorrow. No updates today.

I do agree yes that the folder is back heavy. But with the battery in the front downtube and motor, I expect it to help a little bit. I sure ain't gonna yank the throttle in the lowest gear.

 

[nukezero]

frock - ran into my first problem tonight. I can't insert the BBS into the bottom bracket. It gets stuck. The bottom bracket for sure is a 68mm.. but for some reason it gets jammed half way. I tried turning up and down but I feel like the threads on the bb and the threads on the motor are inter-meshing.

what to do???

 

[footloose]

Had a similar problem: BBS02 would insert halfway into bottom bracket shell, no further. Turned out the shell wasn't absolutely round. Had a blob of braze or weld grunge on the inside surface. Didn't interfere with a normal bottom bracket but did interfere with tighter tolerance fit of BBS02. Ground blob off carefully with half inch sander drum and Dremel tool. Fixed problem. Hope yours is that simple!

 

[nukezero]

AS PROMISED!

Took me 3 hours to put this in. The two hardest part was the bottom bracket would not slide in. I had to wiggle with a shtload of elbow grease. The good news is the threads on the motor stud was not damaged at all. Somehow, I think this 68mm bottom bracket isn't exactly true on the inside so it was a bit lopsided.

The second difficult part was installing the stupid LCD screen. It was tough to hold and squeeze the bracket mounts and screw at the same time. That took a lot of fun.

Cleaned up a wires a bit, also folded it up to see how it works with slack, and I'm amazed/surprised it can fold with the battery still properly attached. Just need to make sure that I give the batt->motor cable some slack when folding.

Other than that, I took it out for a spin with a helmet and bike light in pitch black against my fiance's wishes. I told her I'd be back in 3mins, but more like 15 mins.

Woosh, on a 13s4p samsung 25R pack that started at 51V, I managed to hit 26.5MPH (display is calibrated for 16" wheels)

This thing is a TORQUE monster. I wouldn't say it pulled wheelies.. but MAN what a TORQUE rush... right off the line. The only strange problem happening is when I apply from brakes, the steerer vibrates and resonates like crazy. When coasting, it does not have this issue. Stem is tight, and so is the front wheel hub so I'm not sure where the vibration is coming from.

The chainline is also perfect with the stock bafang 52T.

 

[puregsr]

How you mount the battery base onto the frame with that hinge in the way?

 

[Leeleeducati]

Looking good! Check the headset and bearings. Then the pivot bolt on the front brakes. If it's still a mystery, try a different compound brake pad.

 

[footloose]

Nice bike! Should stash easily in car trunk or under desk, and I expect that with 16" wheels it accelerates out of the hole like a rocket.

Re speed / handling. My own experience with 16" and 20" wheels (BikeFriday Tikit, BikeFriday SIlk and Raleigh 20) -- both pedal powered and electrified -- is that they are nimble but twitchy at very low speeds, a joy in normal riding at speeds up to about 20mph, and plain scary at much above 20mph. Small potholes, bumps in road, train track crossings etc etc... small wheels seem much more sensitive to them. At speed on small wheel folder, it is way easy (for me) to get into trouble before I see the trouble coming.

Re the front shudder on braking... don't know cause... but the very long front steerer on folders seems to amplify any kind of shudder or oscillation. Hope you can find root cause of shudder and address it. Does it happen mainly in braking from high speeds, or braking at any speed?

 

[nukezero]

How you mount the battery base onto the frame with that hinge in the way?

I engineered it by placing a collar washer m5 in size to raise the back bracket just enough to be over the hinge. Then I use a Titanium M5 bolt to hold it all down.

Looking good! Check the headset and bearings. Then the pivot bolt on the front brakes. If it's still a mystery, try a different compound brake pad.

I tightened the headset more. I think it still there. Pivot bolt on the front brakes are fine. May try a different brake pad. Rear brakes are fine though.

Nice bike! Should stash easily in car trunk or under desk, and I expect that with 16" wheels it accelerates out of the hole like a rocket.

Re speed / handling. My own experience with 16" and 20" wheels (BikeFriday Tikit, BikeFriday SIlk and Raleigh 20) -- both pedal powered and electrified -- is that they are nimble but twitchy at very low speeds, a joy in normal riding at speeds up to about 20mph, and plain scary at much above 20mph. Small potholes, bumps in road, train track crossings etc etc... small wheels seem much more sensitive to them. At speed on small wheel folder, it is way easy (for me) to get into trouble before I see the trouble coming.

Re the front shudder on braking... don't know cause... but the very long front steerer on folders seems to amplify any kind of shudder or oscillation. Hope you can find root cause of shudder and address it. Does it happen mainly in braking from high speeds, or braking at any speed?

Yeah, that was my goal. To be easily transportable and throw it under my cubicle desk. It does accelerate off the line like a rocket. It definitely starts to get scary above 20mph. But I do have 57-305 2.125" tires, which helps a bit.

As for the shuddering, it only happens on front brakes and only happens during braking at high speeds above 15 mph. The rim looks true.

 

[tomjasz]

Nice build! Keep that motor humming.

 

[nukezero]

So I think i may have determined the vibration. When I brake on the front, and look down, I can see the brake pads kind of pulsate in and out. The rim appears to be true. So it looks to me like it's a bad pad. But something else is also concerning to me and I'm not sure if I need to do this. The bolt that is holding down the brake caliper into the fork, seems like there is play. Play as in, you can kind of wiggle it and the brake calipers can shift forward/back. When I brake hard, then I can tell the calipers are moving forward. Am I supposed to tighten down these caliper bolts so that the caliper doesn't have up/down movement, but can still swing left and right?

 

[docw009]

Nice! Is the little dog named Morton?

 

[Ykick]

Am I supposed to tighten down these caliper bolts so that the caliper doesn't have up/down movement, but can still swing left and right?

They should be tightened against a bushing so that they can only pivot in/out in motion to pinch the rim but not up and down along the pivot shaft.

Whatever the cause of the shudder, do figure it out. Front end weirdness ain't nothing to to trifle with.

Cool folder! If I could only have one eBike a folder's the one I'd choose.

 

[nukezero]

Nice! Is the little dog named Morton?

that's Toto-bear, we call her. 4lb maltese.

 

[snowranger]

Nice build.. Any updates? How is the igh holding up with the power?

 

[craneplaneguy]

I too had a little obstruction in my Montague BB. It had a un machined boss right in the center, where it wasn't threaded, and it acted like a hard stop when i tried to insert the BBSO2. The trusty die grinder, after a little thought (am I screwing up doing this???) made that problem go away.

That is a super cool folder. Like my Montague, the frame on your folder allows that motor to tuck up nice and high, very cool, and very compact.

 

[cwah]

no wheelie, not such a strong torque

 

[nukezero]

Nice build.. Any updates? How is the igh holding up with the power?

I am running it at 18A 48V now instead of 25A. The bike is holding up great. There was a time where the rear wheel was not tightened well and the chain got loose and it jumped off the sprocket. When it jumped off, it sounded like I blew up my rear IGH. But thankfully, it was just the chain popping off. I have since tightened it correctly.

Other than that, bike is holding up great. I haven't been riding it for over a month now. The weather is a bit cold out lately. Going 25mph is too cold.