Custom build & salvage of Tangent remnants- Astro 3220 mated to a CYC X1Pro reduction

12-C

100 W
Joined
Oct 14, 2016
Messages
212
My original tangent unit internals grenaded a couple years ago. I decided that since the reduction would be impossible to reverse engineer (even more difficult to source parts now) to the desired tolerances I would take a more conventional planetary-type reduction and mate it to the Astro. This is where the CYCX1 pro reduction came in. This would also mean that I'm using a conventional off the shelf part which should allow me to keep playing should I have any failures.

I had to design a housing to hold the astro, new BB mount plates, spider to hold the sprocket and chainring, and some other minor bits. So I got to work, took about a month of measuring, drawing and then finally designing it in CAD.

I had to have the shaft on the astro cut down shorter, turned and key slotted so that the CYC gear could fit on it. -had a local machinist/hobbyist do this for me.
Astro shaft modification.jpg


For the CYC X1 planetary I wanted to keep things as compact as possible. It was necessary get proper tolerances for the sun gear on the astro shaft to mesh with the planetary gears in the reduction unit to mesh properly. My next concern was grease leakage from the mating surfaces of the Motor housing and the reduction, so I made a space for a spec'd large diameter oring which seals everything between them. I also incorporated a small port to add grease- although I think I will just split the unit anyways to clean and reapply instead.
Motor_mount_2021-Jul-28_06-17-42AM-000_CustomizedView11458243923.png
Motor_mount_2021-Jul-28_06-18-59AM-000_CustomizedView29991538189.png

For the BB mount plates I wanted something that would allow me to quickly disassemble the motor from the bike if I ever want to use the bike for downhill hooliganism. My experience from a couple years ago is that they will not allow ebikes on the mountain. For this I made the mount a split unit.
Drive_side_mount_plate_2021-Jul-28_06-21-36AM-000_CustomizedView7947601576.png

The spider was custom designed as well, and I'm quite proud of it for reasons I'll explain later. I kept the 219 sprocket and chain drive design from the CYC setup although I sourced my own quality kart chain from Panther(the only 219 chain that can be broken to custom lengths and properly riveted using their tools) and custom tooth count sprocket from RK. I used a HD wide crank freewheel from sickbikeparts.com. Now for the part I'm really proud of having worked out. I wanted to use a stainless steel chainring with narrow/wide profile... which meant that my options were limited. All my previous chainrings from the tangent unit were aluminum and they eventually failed due to the odd chain skip/drop here and there and softer material. Also for the particular final reduction I wanted at the crank and the rear wheel I was limited by the chainring BCD/freewheel diameter &BCD/Sprocket BCD. Days.... no weeks of prior internet searching for the proper BCD/tooth count/profile was a headache…. Finally I came across the Wolf Tooth components CAMO chainrings. These come in a 28 tooth count with narrow wide profile. The only problem was that WT decided to create their own standard for the BCD pattern… Which was a real PITA! They did not simply create a radially symmetric BCD pattern…Oh no… they decided to slightly offset all the Bolt holes(ever so slightly but not obviously) just to keep it proprietary I suppose. So I ordered a chainring and got to work reverse engineering. I cast the bolt holes in a rigid cold cure acrylic. Then I got to work with calipers triangulating all the bolt holes to references/each other etc. This is when I realize that the 5 hole BCD pattern was not symmetric. Then I drew this up in CAD. I was a bit hesitant to use this for the final STEP file for the CNC machining so I had the bright idea of 3D scanning the chainring at work using my intraoral dental scanner. It took quite a while to do since the scanner is designed for use in the mouth and the software recognizes tooth like structures as it scans, so I had to get creative with how to make the scanner work. Once I got a working STL of the chainring I imported the file and got to work measuring and creating a reference model for the BCD layout. Suffice it to say I could have probably used the original hand measured unit. Comparing the two I was only off by 0.07mm at the worst, below the tolerances needed for machining the unit. And the thus the spider born. This allows me to use the WT CAMO chainring mated to the 219 sprocket revolving on a crank mounted freewheel exactly as the offset I wanted.
Carrier_2021-Jul-28_06-14-25AM-000_CustomizedView19665338.png
Carrier_2021-Jul-28_06-14-58AM-000_CustomizedView11399134170.png

Producing the custom parts cost about $1000US
Everything works great apart from the upper and lower chain roller guides. There isn’t actually enough space for me to use the stock roller/guide. I will be designing some at some point.

The tensioner on the 219 kart chain uses the CYC kit parts apart from the spring tensioning. I found the spring tension to be too weak. So I drilled some extra holes and put a couple bolts through the side plate and used a door-bumper spring for tension; works great!

20210727_235350.jpg20210727_235441.jpg20210727_235558.jpg20210727_235340.jpg
 

Attachments

  • 20210727_235603.jpg
    20210727_235603.jpg
    394.1 KB · Views: 1,394
Now we're talking, top stuff! Are you running the HV160 through CA3? I have a few parts spare and have pondered something similar (not as well refined as this though)

Congrats...how much fun is it?
 
Yes, still running the hv160 with the ca3 with the astro 3220. In the range of 60x reduction in lowest gear.

It's a beast. The unit hasn't so much as skipped a beat yet. Only problem I get is chain slipping on the rear cassette under hard acceleration... up hill lol. So I try and take it easy on that. Ive had yucky failures before from this.

Im pondering a belt conversion for bike now. Ive read mixed reviews on longevity etc. Would like less noise. Also considering the brass planetary gear set for the same reason. Im just worried about the longevity/ strength.

Also considering getting a new spider machined with a chain line offset a few mm further toward the largest gear in the back. This would allow for a straighter chain path for the largest gear, which under power would prevent against the slight lateral pull from turning it into a taco. Had this happen once even though im using the sram pg990 solid carrier.
 
I really need to learn to use a CAD programme!

I am currently working out how to run a direct drive to the left side rear and keep the disc brake.

Others have done so but finding adapters and precise details is proving a challenge. Going back to an Astro and a direct drive with a custom made frame is the ultimate plan...time and research for the correct parts and lay out is needed. Great to see the HV160 still kicking!
 
There are bcd104 steel narrow wides (asymmetric ones, so even better) on aliexpress.
 
Ferret,
I'll take a look back. I don't think I modeled the cyc, just used caliper measurements to build out my parts from there. I'll post those for you if that's the case. I only had the cyc reduction to work with. I can't comment on other dimensions.
 
@ferret

The outer diameter is 93mm
Widest outer dimension at mount bosses is 106mm
Wall thickness about 2.85mm
Height of unit 22.8mm with 5.5mm outer cover
Outer cover has 2x M5x0.8 on a 62mm BCD layout for the chain guard
4x mount holes are for M5

20210823_215740.jpg
 
Rough internal of the unit
 

Attachments

  • 20210823_215959.jpg
    20210823_215959.jpg
    183.7 KB · Views: 1,085
Did you ever get/try the cyc torque sensor bottom bracket with this set up?
 
Back
Top