Custom cruiser build

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#1


I am part way through a scratch build and wanted to make sure I had my head screwed on right before I spent a lot of money on a crank drive. The bike (see picture) is loosely inspired by c. 1920 motorcycles. I'll explain why I want a crank drive, and which one, after a short preamble so that it becomes clear why the bike is the way that it is.

Firstly, I wanted it to be a capable pushbike. It is huge and it isn't light but it all works just fine. The huge painted rims rule out rim brakes, so I have a disk on the rear, and as the springer forks don't have a mount point, I have a Sturmey Archer drum brake on the front. Gears are essential where I live, so there is a Shimano Alfine 8 speed hub on the rear. So no spare hub ...

The bottom bracket is a sodding awful old-school BMX size. I've used an adaptor and it has a standard UK threaded bearing with a tapered spindle and taper cranks.

My first choice for a crank drive would have been the Bafang, but visual inspection of photos suggests there isn't space between the motor and the integral spindle for my old-school BMX oversize bottom bracket (58mm?).

My next choice would be the GNG 48/60V brushless chain drive. Or possibly the older model with the belt primary. I'm even wondering if I can tilt it over inside the frame. The GNG looks a bit micky-mouse, but might fit with the overall look of the bike.

My last choice would be the Cyclone. It just looks naff. That tensioner looks like something I would do when I can't be arsed to do it properly. Perhaps I am misjudging it.

Is there anything I've missed? Any better ideas or suggestions?

Lastly, I'd like to run 48V LiPoFe4. I've never ordered batteries, and the whole battery thing is doing my head in. I'm fine with electrical stuff and had planned to build a custom removable battery frame to sit inside a varnished wooden cabinet inside the bike frame. I like the ease with which Headway batteries go together. Is there a similar but better choice? Who would be the supplier of choice?

Sorry to trouble you with the usual questions, but as you can see, nothing is entirely normal in this build, and I can't afford to make a mistake :)

Thanks
Colin
 
D

Deleted member 4366

Guest
#2
The various GNGs all use a standard 68mm BB. Does that rule them out? I Cant quite figure out what yo're saying that you have down there. Whatever you fit, you'll need a free-wheeling crank, Which you can get from Eclipse ikes. I'm not sure if you need a longer B spindle for it. You'll have to ask them:
http://www.eclipsebikes.com/freewheel-chainwheels-c-32.html

I like your global positioning system over the back wheel. It just needs the right brackets to keep it stable.

LiFePO4 is very heavy for it's size. I'd use LiMnNiCo. This one will be good to supply 1500W. I have three of the 36v ones which I run at 30 amps each:
http://www.bmsbattery.com/48v/249-48v-10ah-lithium-ion-electric-bicycle-battery-pack.html
 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#4
The various GNGs all use a standard 68mm BB. Does that rule them out? I Cant quite figure out what yo're saying that you have down there. Whatever you fit, you'll need a free-wheeling crank, Which you can get from Eclipse ikes. I'm not sure if you need a longer B spindle for it. You'll have to ask them:
http://www.eclipsebikes.com/freewheel-chainwheels-c-32.html

I like your global positioning system over the back wheel. It just needs the right brackets to keep it stable.

LiFePO4 is very heavy for it's size. I'd use LiMnNiCo. This one will be good to supply 1500W. I have three of the 36v ones which I run at 30 amps each:
http://www.bmsbattery.com/48v/249-48v-10ah-lithium-ion-electric-bicycle-battery-pack.html


D8veh - thanks for the reply. You are correct - the GPS is unstable, and more suited to the van, but I have a new miniature version (see picture) for the bike.

I've attached a close-up of the BB for clarity. What you are seeing is a BB 68mm wide in the direction of the spindle. The diameter is 58mm, which I've reduced with interference-fit adaptors so that it takes a Shimano sealed, threaded bearing.

My belief is that the Bafang mid-drive won't fit because the BB diameter is too large. I believe the GNG drive will fit. I would have to fit a new spindle and freewheel chainwheel as you suggest (this is supplied), and I would expect it to thread into my current adaptor. This is what I will go for unless persuaded otherwise.

I haven't given the Cyclone serious thought, but would if someone made a case for it over the GNG.

The battery you recommend seems to come as a shrink-wrap 'blob' - would you think it feasible to unpick it and rebuild for aesthetic reasons?

Thanks again,
Colin
 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#5
D

Deleted member 4366

Guest
#6
The battery is more or less glued together, so not easy to re-configure; however, the photo in the listing is not representative, neither are the sizes they quote because they change the size of the cells. No point in asking them either because they'll probably just quote what's in the listing. The 36v one comes in two versions: long and thin, and short and fat. Here's a couple of photos of the short fat one. I'm pretty sure that the 48v will be the same as this version with extra cells in the direction of stacking.




I've never fitted an 8Fun crank-motor, but my understanding is that it fits a standard 68mm Shimano type BB. It doesn't use the thread. It just slides through and has a nut on the outside. The whole assembly could more or less rotate in the BB as far as the frame allows, but it's prevented by an anti-rotation bracket

The GNGs work, but they're a bit noisier than other options, and you have to keep adjusting and lubricating the chains. The free-wheel clicks when you're pedalling too, which is a little annoying. I think that the Bafang will be much better if you can fit it.
 

Clockwise

Esteemed Pedelecer
Jun 28, 2013
438
8
#7
Could I have some more info on the bb adapter?

I have a beach cruiser and it has the same awful american stuff and I keep thinking I should either sell it on or make something of it.
 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#8

Clockwise

Esteemed Pedelecer
Jun 28, 2013
438
8
#9
D

Deleted member 4366

Guest
#10
It's a bit of a shame you can't get them without the threads, which are not needed for the Bafang crank-drive.
 

Alan Quay

Esteemed Pedelecer
Dec 4, 2012
2,341
79
Devon
#11
Could I have some more info on the bb adapter?

I have a beach cruiser and it has the same awful american stuff and I keep thinking I should either sell it on or make something of it.
If you can get hold of a trek Clyde, and want front wheel drive, things are easy. The trek is all standard MTB bits, but with non sus, steel forks, 4 speed shimano nexus hub gears and V brakes.

Comes with flat bars that really need to be swapped for something more laid back (whick means new brake/gear cables).
 

Clockwise

Esteemed Pedelecer
Jun 28, 2013
438
8
#12
If you can get hold of a trek Clyde, and want front wheel drive, things are easy. The trek is all standard MTB bits, but with non sus, steel forks, 4 speed shimano nexus hub gears and V brakes.

Comes with flat bars that really need to be swapped for something more laid back (whick means new brake/gear cables).
Oh, you are one of those people who likes bikes they can actually ride/use lol

 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#13
Had this one on my watch list for ages. Does it work well? Rather not swap one issue for another lol

www.ebay.co.uk/itm/111215155503?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649[/quote]

That adaptor looks similar or identical. I found they were a tight interference fit and I made a press out of 12mm threaded rod and very thick plywood. There is a left and right side which isn't marked and if you put them in the wrong way like muggins here you will have to make another piece of improvised tech to get them out again. That was hard.

In use with the shimano crank bearing in place they seem rock solid.
That adaptor looks similar or identical. I found they were a tight interference fit and I made a press out of 12mm threaded rod and very thick plywood. There is a left and right side which isn't marked and if you put them in the wrong way like muggins here you will have to make another piece of improvised tech to get them out again. That was hard.
In use with the shimano crank bearing in place they seem rock solid
 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#14
It's a bit of a shame you can't get them without the threads, which are not needed for the Bafang crank-drive.
They are alloy, so I guess thread removal is not so hard. A little bit of gratuitous cross-threading might do it :) The larger issue is the minimal gap between the Bafang crank insert and the motor - it is hard to tell from photos, but I will wager there isn't space for the outsize BMX BB to fit in the space.
 

shemozzle999

Esteemed Pedelecer
Sep 28, 2009
2,821
90
#15
They are alloy, so I guess thread removal is not so hard. A little bit of gratuitous cross-threading might do it :) The larger issue is the minimal gap between the Bafang crank insert and the motor - it is hard to tell from photos, but I will wager there isn't space for the outsize BMX BB to fit in the space.
Hi Valkeerie,

At best there is about 7/8mm unobstructed clearance from the BB to the motor side wall, so maximum o/d 33.5 + 2x8 = 49.5mm diameter

There is a fillet on the base of the motor casting and a draft angle which gives the impression of a larger gap. You might be able to squeeze another 4mm on the diameter (i.e. 53.5mm diameter) if you radius the adapter to blend with the fillet but the figure of 58mm you quoted exceeds this so unfortunately I am afraid the Bafang won't fit.
 
D

Deleted member 4366

Guest
#16
I get it now. That's a bummer!
You could get someone to turn up a couple of eccentric spacers. The O/D would be the same as your present ones, and the I/D the correct size for the Bafang insert. You don't need them to be threaded. In fact, it would be better without threads. I'd keep the axial screws to hold the two sides in the right position re eccentricity.
 

Valkeerie

Finding my (electric) wheels
Oct 23, 2013
10
0
#17
Hi Valkeerie,

At best there is about 7/8mm unobstructed clearance from the BB to the motor side wall, so maximum o/d 33.5 + 2x8 = 49.5mm diameter

There is a fillet on the base of the motor casting and a draft angle which gives the impression of a larger gap. You might be able to squeeze another 4mm on the diameter (i.e. 53.5mm diameter) if you radius the adapter to blend with the fillet but the figure of 58mm you quoted exceeds this so unfortunately I am afraid the Bafang won't fit.
Thank you Shemozzle ... those are useful measurements. I was hoping someone would have the Bafang drive. I'll double check my BB but they reinforce my believe that the clearance is small and unlikely to fit.

Colin
 

shemozzle999

Esteemed Pedelecer
Sep 28, 2009
2,821
90
#18
You could try drawing it up and see if offsetting the hole in the adaptor as d8veh suggested would leave enough meat to support the motor when fitted.
 

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