NoPhart

Parts are coming in. Everything except the 130BCD BBS02 spider adapter and 118T Gates Carbon Belt have arrived.

Gates goodies: 50T 130BCD Gates front sprocket, 28T Gates rear cog, Origin-8 cassette single speed spacer kit and a 42T Lekkie Bling Ring for size comparison.



Mounted the 28T Gates rear cog up in what is probably its' ideal location using both large support spacers to show how nice it looks this way. Only one additional spacer is need in this configuration (thin red one on the inside).



Then I mounted the rear cog as far out on the cassette as it will go with the cog offset to the outside and mounted it up. This is the key measurement that can be used to calculate if belt alignment can be achieved. The 28T Gates cog centerline is 10mm inward from the right side of the 135mm rear frame.



Here's a top view of the belt line just for perspective.



I don't have a BBS02 here yet to measure the front Gates 50T belt centerline from the edge or centerline of the bottom bracket yet, but I'll do some quick calculations from schematics of the BBS02 and the CS-RK3 and post them up.

NoPhart

Here are my quick calculations. Half the 135mm rear frame is 67.5mm. The 28T Gates cog is 10mm in from the right side, so it's 57.5mm from the frame centerline. The BBS02 drawings I have say the BBS02 sprocket mounting surface is 50mm from the centerline, so without even moving it inward via a spider adapter and the 50T Gates sprocket offset there is 7.5mm to work with. Not sure there will be enough room to use both Origin-8 wide black support spacers, but it looks like belt alignment won't be a problem if those numbers are correct.

PatrickGSR94

Wow this will be awesome, possibly the first ever e-assist mid-motor belt drive setup?

NoPhart

Finally got around to ordering a Bafang BBS02 750W/48V mid-drive with color display to get this project rolling. Also received this beautiful 130BCD alloy spider adapter from France.



It fits the Gates 50T front sprocket perfectly and looks good doing it!

NoPhart

The Bafang BBS02-B 750W/48V motor with 850C color display arrived and I quickly placed the 130BCD spider from France and Gates 50T CDX belt-ring on it. Everything clears!



It looks like with these parts the Gates belt-ring center line is ~22mm from the large flat surface of the motor facing the BB, but there is a ~2mm indent for the BB to seat into, so I’m getting ~20mm from the 68mm BB edge to the center line on the Gates 50T belt-ring. That gives ~54mm from the frame center line to the Gates belt-ring center line [(68/2) + 20 = 54].

The great news is even the chainring bolts clear and there will be no issue aligning the Gates Carbon Drive CDX belt with the CS-RK3 cassette hub. A Gates belt drive BBS02-B build is easily doable with these store bought parts!

Time to start putting it all together…

NoPhart

Getting down to the nitty-gritty on belt alignment now that the motor, spider and belt-rings are all here. I even bought a digital caliper for better accuracy, so the numbers have changed a little bit.

1) When I measure from the left flat side of the gear reduction housing that goes up against the right BB to the spider mounting surface on the BBS02B I get 24mm, but there is a 2mm indent in the area that sits against the BB. That puts the chainring/spider mounting surface on the BBS02B 22mm from the right edge of the BB.

2) The 130BCD spider from France is flat on the back where it mounts to the BBS02B, but has a 2mm indent into the surface where the belt-ring mounts on the side towards the motor.

3) The Gates 50T belt-ring is 3mm thick at the mounting point and the Gates specifications for this chain-ring state the center line of the CDX is 3.1mm from the mounting surface. So the center line of the CDX ends up virtually the same (0.1mm difference) as the other side of the mounting surface edge.

All that puts the BBS02B chainring/spider mounting surface 56mm from the frame center line [(68/2)+22=56]. The spider indent adds another 2mm (56+2=58), but the Gates 50T CDX center line is 3mm towards the motor, so 3mm gets substracted back. That puts the Gates 50T CDX center line 55mm from the center line of the frame (58-3=55).

Boy I hope I have all that right...

NoPhart

Using those digital caliper measurements, I need to position the rear Gates 28T belt cog at 12.5mm inward from the right side of the 135mm frame surface [(135/2)-55=12.5).

Even though the calculations changed slightly using accurate tools, the Gates Carbon Drive CDX belt will align okay. The rear cog ends up 2.5mm inward from its' outer most mountable position.

BruceMetras

Just for reference, the Bafang centerline using their stock chainring is 50mm +-.05.. that would put you roughly 5mm outboard .. hopefully the centertrack system will allow for that .. looking forward to your finished project..

NoPhart

If that is the case, then the stock Bafang chainring must have a 6mm dish to it, because the chainring mounting surface came in at 56mm.

I don't know of any IGH's that have the ability to be setup with a 55mm belt-line other than this CS-RK3 cassette IGH. One could possibly squeeze out another 1-2mm inward at most on the front belt-ring by adding spacers or using a flat on the mounting side spider, and indenting the belt-ring to spider bolt heads.

The Nexus 3 SG-3D55 is 43.85mm. Most 135mm IGH's are 43.65-43.85mm according to the Gates Tech Manual.

NoPhart

Here's a thought:

One can fabricate a big dish Gates Carbon Drive CDX belt-ring using a Likkie bling Ring and a 50T Gates with machine work and welding or possibly go with a machined and drilled slightly larger than 50T Gates belt-ring and using bolts at select Lekkie chain teeth locations.

BruceMetras

I pulled the dimensions out of the Bafang manual .. the stock ring does indeed have a lot of dish..

NoPhart

Waiting on chianring bolts from Taiwan...

PatrickGSR94

huh? Are they not standard chain ring bolts that you could pick up from your LBS??

NoPhart

I found some cool blue 7075 alloy chainring bolts the "proper length" on eBay for $4 shipped, so I grabbed them. The ones I've been using for testing are not the right length and my best guess is my LBS's wouldn't have what I wanted, but could order them. When that has to be done I get killed on shipping and costs. For whatever reason I can always get better prices than what they claim their cost is (?). Don't have that issue with in stock parts or labor costs at my LBS.

I've watched my costs on this build at every turn. It is close to $3K now and I haven't even bought the 48V/20Ah battery yet ($550+ depending on battery type). Custom builds aren't cheap, but you get exactly what you want. Small (bolts, nuts, spacers, etc...) and large (handlebars, stems, beltrings adapters, etc...) 6000/7000 series alloy and Ti bits add up quickly. It really depends on what quality and weight parts you desire, plus the color and look you want.

Anyway, you typically only wait 1-2 weeks for mail order; including international stuff.

PatrickGSR94

I see, yeah understood on all points. I lucked out with my utility bike build. I snagged a Marin Pine Mountain MTB steel frame with disc and rack mounts for $60 off a guy locally. It was a 2006 but looked nearly brand new. Then I was able to transfer most parts off my older aluminum MTB, and then buy a few more parts and build up the old MTB in a different way. So I basically took one old bike + $300 and ended up with 2 bikes, one of them being an upright riding utility bike with disc brakes. All it needs now is the BBS02 mid-drive setup and battery, which hopefully won't be much more than $1K.

NoPhart

The fun holiday season will be over after tonight's New Years Eve celebration, then the 2017 bicycling fun can be begin...

Because this is a new custom frame that I paid good money to have the BB faced, I really don't want to install the standard Bafang mount support bracket that digs into the BB edge, so I made a replacement bracket that uses a frame support to hold it in place high above the ground out of aluminum.



I will also be putting a small bead of strong polyurethane caulking on each BB edge prior to tightening the BBS02B down permanently.

Still haven't decided on battery type and placement. Santa delivered a nice pair of JANDD Folding Grocery Panniers, so a rear rack is in my future. Because of that, I'm leaning towards a rack battery in a stealth bag or killer whale type battery mounted to the top of the rack. Because they are only about 3" wide a killer whale type battery won't interfere with the panniers being installed and removed on the side rails.

NoPhart

Before mounting it up I wrapped the piece that slides in with one thickness of aluminum duct tape for a real snug fit, then put a bead of caulking on each side of the BB.



Then I slide the new custom bracket on and attached all the nuts and bolts.



All buttoned up!

NoPhart

Starting the New Year off with a bang. Gates Carbon Drive installed and looking sweet.



I'm getting excited now!

PatrickGSR94

So awesome, can't wait to see it finished, and to get the money to finally start my conversion!

RRC22

I just like to shift my ebikes too much to get excited about belt drives. Interesting effort though.

snowscum

I think he has a 8speed hub. Build is looking sweet!

NoPhart

This baby is actually setup as a 3spd IGH, but anyone that has many miles under their belt with a Bafang mid-drive knows that the assist levels act just like additional gears; in that each click of the 1-5 or 1-9 (depending on how you set it up) increases or decreases your speed. If you like to shift set it to 1-9 X 3spd IGH and you have a 27spd!

Today's project will be installing the shifter cable and looking up all the torque specifications, then going through each nut and bolt on the bike. Many of the higher end parts have torque specs right on them.

Does anyone know of a generic standard torque table for bicycle components I can reference for unlabeled parts?

With any luck I'll be pedaling and shifting this week without power.

RRC22

With the way this post has changed from the 1st posting, I guess both of us got confused.

NoPhart

Well, the idea of doing a beach cruiser did get tossed out early; not that I wouldn't still like an Electra Lux Fat Disc Brake 7spd Cruiser base electrified beach machine and I did mix in a bunch of MY1018 side project that never got tested on this frame in the end... My bad.

Found this great list of torque specifications for reference when not included with a p[roduct or stated right on a product. The ranges should keep me(you) within reasonable levels.

https://www.williambenedict.com/bikes...rque-chart.pdf

Hopefully others will find this helpful too.

PatrickGSR94

eh I usually just snug bolts by hand until it feels pretty tight. Never been a problem.