CroBorg Commuter

[Alan B]

Pedal drivetrain progress Update

Took a visit to ebikessf.com today. ilia worked on the ATS Schlumpf drive installation. The bottom bracket shell is nicely chamfered now, but the body of the drive touches the ring around the swingarm bearing. So some cone washer spacers need to be ordered.

The chainring is also fitted, which means that the drive's bent ear has been coaxed into alignment. Need to find the proper tool to tighten the chainring bolts...

ilia was impressed with the forks and the frame.

[Alan B]

Freewheel Spacing

I previously measured 2.3mm of space between the freewheel and the body of the motor. Today I tested a 2.25mm spacer there, and it pushed the freewheel out well beyond the end of the freewheel threads. Turns out the Dicta freewheel was already contacting the shoulder. The space I observed was at a larger diameter. So no spacer is needed or useable in a practical sense.

I didn't remeasure the freewheel versus end of threads, but it appears that the freewheel hangs out a fraction of a mm farther than the threads. So there is no point in trimming the threads back to get more room, the freewheel is the widest element now. A "C" or "D" washer is needed to keep the dropouts from rubbing on the freewheel.

[Alan B]

Freewheel Info

I tried to measure the freewheel edge to end of the Cromotor's threaded freewheel mounting tube, and it is essentially flush. I also tried to measure the inset of the axle shoulder, and it is not easy to measure, but it is very slight. I didn't get a good reading, but it appears to be a small fraction of a mm. So I gave up on measuring them and took some photos:

[acuteaero]

Hey Alan- Love the photos- great combo of pretty parts and good camera/technique

Looks to me like the FW side could use regular flat washer(s) between the axle shoulder and the dropout- 5/8 nominal size would likely work out fine- does this seem right or reasonable to you?

When I'm making up the prototype C washer out of aluminum, 1" OD, what would the most optimal thickness be? Still ~2.5mm? I may be able to do this before the end of the week, for dead certain before the end of next week.

-H

[Alan B]

A regular washer should work, though it doesn't get quite the shoulder support that a "D" or "C" washer would.

I grabbed those pics this morning before I went to work, I'll try the same on the flip side in tomorrow morning's light and verify spacing. How much clearance between the hub and the dropouts is prudent? The dropouts are about 130 mm and the motor is wider than that, so I will be bending dropouts outward slightly. I'm trying to minimize that but we need enough clearance.

OK, I just went to the garage and used a flashlight plus an off-camera slave flash to get some shots of the wiring side of the Cromotor. There is a bit of axle shoulder beyond the disc brake flange. Aboutn 1mm. So the washer needs to be disc plus screwhead thickness plus dropout clearance minus the approx 1mm to work with a disc, or just a couple of mm to work without a disc. I don't have the rear disc to measure yet, and I don't know how the disc is going to line up with the chainstays. Ultimately it might need a bit more washer width, but this might decenter the tire if it gets too wide.

So 2.5mm is about right for no rear disc, but more is needed for the rear disc. I don't have to start with clearance for the rear disc, though it might be smart to start close to that.

Here are some quick shots of it:

[Alan B]

Wow, a package from Yasusu arrived!

[Alan B]

The Yasusu package was shipped 3 days ago. Amazing!

The shock is installed. I had to grind the shock mounting plates a little to clear the shock top flange.

I also had to shorten the bushings on the low end of the shock. My swingarms are a little tighter than Stevil's, I should have used my dimensions instead of using his on that part. His were 30mm spacing, mine 25mm.

[Alan B]

OK, here is the shock mounted under the seat and connecting to the swingarm on the right, photographed in the dark with background fill flash:




Here is the beveled bottom bracket shell, ready for the Schlumpf:

[Alan B]

After returning from the Maker Faire I set up the Borg and re-spaced the front calipers, ending up with 2.10 mm of spacers.

Then I changed over the temporary steel bolts for stainless on the swingarm.

I tried a 5/8 washer on the motor's freewheel side and the OD is too large so it hits the threaded freewheel tube. The washers are needed to install the hubmotor wheel.

I reviewed various techniques for seating the star nut in the steering tube. I'll probably get a piece of all thread and make a tool to pull it in. That looks like the best technique.

[Alan B]

I found some cone washer spacers so we'll try to install the Schlumpf again early next week.

I ordered a small JST crimper for those little pins on the various ebike connectors. This crimper covers 1.0, 1.4, 1.6 and 1.9mm pins.

[Alan B]

Headset installation is complete. Turned a tool on the lathe from 1" 6061 aluminum bar to center a piece of 6mm allthread from below in the steerer tube and pull the headset star-nut into the steerer tube. Reassembled the headset and stem and adjusted them properly.

Off to the hardware store to get some more parts to make another tool...

[Alan B]

OK. Back from the hardware store, and made the tool and used it. Made a dropout spreader from 3/8 allthread. Spread the dropouts from 130mm to 135mm. In hindsight, should have put a 135mm spacer in there when I was pressing the swingarm bearings, perhaps.

I was away camping this weekend, or I would have made more progress. Just got back this afternoon.

[chroot]

Hi Alan, Is the freewheel made by White Industries freewheel? and I have a question to ask, Do they have 14T freewheel?

I need get a single freewheel for my cromotor, I am thinking going use 10g spokes with the alumnium dirtbike rim and I looked your cromotor seems uses 12g spokes?

Lastly, Are you going ilia's grand open shop tonight? and I will be there.

Freewheel Info

[Alan B]

The White Industries freewheel doesn't fit, so I bought a cheap Dicta for now and it fits perfectly. The Cromotor threads are so long they need to go all the way through the freewheel, and most freewheel designs (including the White) don't allow that.

I believe my Cromotor spokes are 12 gauge as that is what was required for the moped rim. Conical washers were fabricated for the motor holes to fit the spoke heads. I should take some good closeup photos of those. Stevil did a great job on the wheels.

I won't be at ilia's new store tonite as I have a previously scheduled appointment elsewhere to get my Schlumpf drive fitted.

I was at ilias' new store already.

We are getting really close to having this CroBorg come alive!!

[Alan B]

Well, I know everyone is waiting on the edge of their seats, or they are totally bored with this thread...

Another fail. No Schlumpf tonite.

The 4mm cone washer is not wide enough.

So we need to find the 6mm special aluminum Schlumpf cone washer, or make one. I may be able to make one. Looks like a good job for the lathe.

It also looks to me like the swingarms are not symmetrical from side to side (from the rear the rear wheel appears to be pointing slightly left), so we may need to do some frame bending on them. It is off more than the 5mm I adjusted them, so this was already off before I made the adjustment. Of course when I made the adjustment it seemed to get worse. However this is not enough of a problem to slow things down now, it will be a chore for later to straighten things out...

[MattyCiii]

Another fail. No Schlumpf tonite.

The 4mm cone washer is not wide enough.

I know exactly how you feel.

Please do post if you find a source for the 6mm, I could use a little more space in my chain line.

[Alan B]

To make a 6mm Schlumpf cone washer:

Start by slicing off some 2" 6061 Aluminum barstock using a special non-ferrous metal cutting blade on a 12" chop saw:




Chuck it in the lathe, turn the OD, face it, cut the 45 chamfer, then remove material from the ID, starting by drilling, then follow by boring out the extra material:




Keep boring until the desired ID is reached:




Part it off, cut the reverse inside taper (not shown) and clean it up, (note the real Schlumpf part is on the right):




Stock 4mm spacer on the right, homemade 6mm spacer on the left:




Slide it on the Schlumpf drive (4mm aluminum Schlumpf on the left, 0mm steel Schlumpf on the right):




Hopefully this will work where the 0mm and 4mm washers failed.

I had a long day today, getting this made feels good. Hopefully it will do the trick!

Note that they recommend aluminum spacers with steel frame bikes and steel spacers with aluminum frame bikes.

[chroot]

Gotcha, Which is the english or metric threaded for cromotor's freewheel thread and I need order one.

The White Industries freewheel doesn't fit, so I bought a cheap Dicta for now and it fits perfectly.

[Alan B]

It is the standard English thread freewheel, not the smaller BMX metric one. The cheap Dicta's drop right on. That's what is in the pics on the previous page. Smallest is 16 teeth. Smaller ones are generally metric.

[Alan B]

Houston, we have Schlumpf installed.

Next challenge: Motor Washers...

[acuteaero]

I swear I'm going to make some sick washers for you just as soon as I finish eating, here.

-H

[Alan B]

OK H. That would be excellent! Otherwise I'll have to hack something together!!

Here's the installed ATS Schlumpf (big thanks to Stefan at CycleMonkey.com):




Here is the tool I hacked together for the star nut install:




Here is a closer view of Stevil's special washers on the 12 gauge spokes in the Cromotor, they seem to fit really well:




That's all for now. More progress this weekend, hopefully!

Thanks to everyone helping out here!!!

[acuteaero]

Bam!

Now, to see if they fit right, and how well the design works-

[Alan B]

Wow, those look great!

[Alan B]

Notes regarding the ATS Schlumpf on the Greyborg frame:

The 6mm aluminum spacer was JUST adequate. It may require 6.5mm. Several things seem to be just about touching - the swingarm sticks out beyond the bottom bracket in the ring that surrounds the bearing, and the swingarm tubes, and the screw head for the swingarm bolt. The back of the Schlumpf is a plastic cover keeping lube in and dirt out, and it may be occasionally touching, but there is no pedaling resistance so it is a soft touch.

This 6mm aluminum spacer was not included, but is available from Schlumpf dealers. It can be fabricated if you have a lathe, but it is a $7 part that takes an hour or two to make the way I did it. I chose to make it because it was not clear how long it would take to order one.

Note that for steel frames an aluminum spacer is recommended. The drive comes with a 0mm steel cone ring suitable for an alloy frame that needs no extra clearance.

We also had some additional problems from the shipping damaged ear on the drive in mounting the chainring and getting it to run true. Chainring spacers were installed and the parts tweaked to get it to be fairly true. When the hubmotor is mounted it will become more clear where the chainline is, and the chainring may have to be spaced further out. We did what we could without the motor, hopefully it will be adequate at least to start with.