The Unofficial 'CroMotor' Owners Tech-Tips Thread

[oatnet]

After alot of mishappens, my motor is being laced to a 17" 2.15 moto rim with 2.75 tires...
How can I calc the final wheel size?

Moto rim or Moped rim? Moto rims are new to me, but here is what I have been using. The height of the tire is added to both sides of the wheel diameter to get total diameter:

17"+2.75+2.75=22.5" diameter

This is 100v performance based on the calcs I have been using. I am not sure if the no-load x 80% = road speed holds true at higher MPH with increased drag, but we'll see.

22.5 Diameter
70.65 Circumferance, inches
5.89 Circumferance, feet
12.98 KV of CroMotor
100.00 Voltage
1298.00 RPM Unloaded
86.84 MPH unloaded
938.55 RPM loaded (80%)
62.79 MPH loaded

 

[zombiess]

After alot of mishappens, my motor is being laced to a 17" 2.15 moto rim with 2.75 tires...
How can I calc the final wheel size?

Moto rim or Moped rim? Moto rims are new to me, but here is what I have been using. The height of the tire is added to both sides of the wheel diameter to get total diameter:

17"+2.75+2.75=22.5" diameter

This is 100v performance based on the calcs I have been using. I am not sure if the no-load x 80% = road speed holds true at higher MPH with increased drag, but we'll see.

22.5 Diameter
70.65 Circumferance, inches
5.89 Circumferance, feet
12.98 KV of CroMotor
100.00 Voltage
1298.00 RPM Unloaded
86.84 MPH unloaded
938.55 RPM loaded (80%)
62.79 MPH loaded

FWIW, your estimates come out almost identical to mine. I'm also estimating the winding resistance at 0.6 ohms which means it's probably going to take right around 100A to reach the 60+ MPH speeds, but we don't know how this motor is going to act inductively, it might not be as big of an amp hog as we think.

I arrived at my sim numbers based off posted examples. I don't know if most of us will have the power needed to reach the BEMF point. Could be a good reason to go with 24 and 36 FET controllers, more amps for under 100V use since this motor might want them. I heard one guy ran a 18 FET at 70A, 84V top speed over 80km/hr with a 26" wheel.

In a talk I had with Markobetti he said he won't run less than a 24" wheel due to the torque of this motor.

This motor is also rated for 4kw continuous without vented covers or is it just 2KW?

I should probably go to the garage and fix my controller now and start building a new 8 gauge phase wire harness for this when I get it later today.

 

[gensem]

Moto rim or Moped rim? Moto rims are new to me, but here is what I have been using.

It there a diference Oatnet? I said moto because the first wheel the guy offered what a 2.5 one wich was intentend to be used in MX.. but im not sure about this 2.15 one...

 

[gensem]

FWIW, your estimates come out almost identical to mine. I'm also estimating the winding resistance at 0.6 ohms which means it's probably going to take right around 100A to reach the 60+ MPH speeds, but we don't know how this motor is going to act inductively, it might not be as big of an amp hog as we think.

I arrived at my sim numbers based off posted examples. I don't know if most of us will have the power needed to reach the BEMF point. Could be a good reason to go with 24 and 36 FET controllers, more amps for under 100V use since this motor might want them. I heard one guy ran a 18 FET at 70A, 84V top speed over 80km/hr with a 26" wheel.

In a talk I had with Markobetti he said he won't run less than a 24" wheel due to the torque of this motor.

This motor is also rated for 4kw continuous without vented covers or is it just 2KW?

I should probably go to the garage and fix my controller now and start building a new 8 gauge phase wire harness for this when I get it later today.

The motor is rated for 3kw, at least its what its printed on its covers. Even tho a 17" rim with 3" moped tires ll end up being 23" in the bicycle world.
There is no such a thing as too much torque... is our throttle modulation that sucks. Two diferent fixes for that... either use the 3 speed mode on med/low to take of traffic lights or use CA current throttle.
I ll be using a 24 4110 controller, but as I want my commuter bicycle to be reliable I ll either use 70v 100a or 90v 80a.

 

[zombiess]

Will hopefully be running tomorrow. Building the 8 gauge phase wire and hall wiring extensions tonight.

Wheel builder wasn't too happy about putting this into a 20" BMX wheel and told me to keep an eye on it due to the brace angle of the spokes and the possibility of the nipple cracking. Far from perfect but I have a 9C done exactly like this and it's been find for 200 miles of abuse now and I don't think the spokes/nipples on it are as good as these.

 

[johnrobholmes]

Yeah, I wouldn't be happy building that either. Watch the rim around the nipples, it will likely crack before the nips.

 

[zombiess]

Yeah, I wouldn't be happy building that either. Watch the rim around the nipples, it will likely crack before the nips.

He wasn't worried about the rim at all probably because it has eylets, thanks for the tip, I'll check it when I do my inspections. He said the hub metal as a MF'er to drill and is some strong stuff for the new spoke holes. I'm just lucky that I have a local guy willing to take on my weird, hard to do wheel project.

 

[johnrobholmes]

Eyelets or none, the rim will still start to crack over time from the constant loading and unloading. It is just a question of how long it will take. 2000 miles would be really good. I have seen cheap rims crack at 200 miles because of lacing and oversized spokes. Your particular rim is of good aluminum, so it may very well last long enough for what you need. Just keep an eye on it so you can stay ahead of any problems that could arise.

 

[zombiess]

Eyelets or none, the rim will still start to crack over time from the constant loading and unloading. It is just a question of how long it will take. 2000 miles would be really good. I have seen cheap rims crack at 200 miles because of lacing and oversized spokes. Your particular rim is of good aluminum, so it may very well last long enough for what you need. Just keep an eye on it so you can stay ahead of any problems that could arise.

Will do. He gave me the same advice, keep a close eye on it. He also ordered this wheel knowing what I was going to have him do. Now I want to ride it.

 

[fractal]

Just got mine today. I've seen pics of it taken beside a 9c, so I decided to the one beside my HT. This thing is FAT. ***(btw, why is my pic "not downloaded yet"??? why can't I see it without clicking on it?)

 

[Doctorbass]

Just got mine today. I've seen pics of it taken beside a 9c, so I decided to the one beside my HT. This thing is FAT. ***(btw, why is my pic "not downloaded yet"??? why can't I see it without clicking on it?)

The 9C look like a particule compare to the beef Cro motor!

 

[Gow864]

How long did the motors take to get from Croatia to you? i'm still waiting 5 weeks later.

Cheers,
Gow.

 

[fractal]

How long did the motors take to get from Croatia to you? i'm still waiting 5 weeks later.

Cheers,
Gow.

It was shipped on november 25th to Gatineau, Quebec.

 

[sn0wchyld]

How long did the motors take to get from Croatia to you? i'm still waiting 5 weeks later.

Cheers,
Gow.

It was shipped on november 25th to Gatineau, Quebec.

thats pretty damn quick for that heavy hunk of steel.

I think you need to shrink the pics to less than 500pixles wide or similar for them to appear instead of a clickable link.

on another note those axles look a damn sight better than the ht axles, not that thats saying much...

who's gonna be the first to post a vid of one in use???

 

[fractal]

How long did the motors take to get from Croatia to you? i'm still waiting 5 weeks later.

Cheers,
Gow.

It was shipped on november 25th to Gatineau, Quebec.

thats pretty damn quick for that heavy hunk of steel.

I think you need to shrink the pics to less than 500pixles wide or similar for them to appear instead of a clickable link.

on another note those axles look a damn sight better than the ht axles, not that thats saying much...

who's gonna be the first to post a vid of one in use???

thanks for the pics tip. and yes, the axle looks way stronger. i wil not be able to try it before april. winter is coming pretty fast around here.

 

[oatnet]

Just got mine today. I've seen pics of it taken beside a 9c, so I decided to the one beside my HT. This thing is FAT. ***(btw, why is my pic "not downloaded yet"??? why can't I see it without clicking on it?)

Wow! Great comparison, thanks!

The board limits pics to 640 pixels wide, your picture is much larger, so only the link is displayed.

Gow, I did the wire transfer for my CroMotor on October 21st JRH received it on November 11th. Accountant said 20-21 days for my address, so he was spot-on.

-JD

 

[zombiess]

Accountant always delivers, these guys are a class act! Took about two weeks to get mine as well after I did my initial wire transfer, gotta love a company that delivers what they say they will. Pretty rare these days.

 

[gensem]

Moped 17" wheel is ready (~22,7inch bicycle size) around 15,8kg !

What do you guys think???

Maxxis 24x 2.4 for size comparison.

Paintjob is not ready yet coz I runned out of matte black spray paint... wheel was regular black and I do not like it shinning.

Next week I should have the frame ready with Doc torque arms and some adaptations. But im still short of front bicycle wheel and 24 fet controller to test the hub motor...


(btw can anyone tell me how to use thumbnails in here)

 

[sn0wchyld]

Moped 17" wheel is ready (~22,7inch bicycle size) around 15,8kg !

What do you guys think???

.....

damn man, that looks tidy. Your bike is going to look like a motorbike though, not a pushy. 15.8kg is pretty hefty too, though bare in mind the 5404 is 15kg on its own! i haven't weighed my own wheel (HT35) but im guessing its around the 10-11kg mark, so your doing pretty well considering the strength of that wheel!

 

[oatnet]

Moped 17" wheel is ready (~22,7inch bicycle size) around 15,8kg !

NICE gensem!

What is the widest point on that 2.75" tire? Is it at the 2.75" tread line, or are the sidewalks wider?

I use a program called ThumbsPlus to crop/shrink my pictures to 640 x 480.

 

[gensem]

damn man, that looks tidy. Your bike is going to look like a motorbike though, not a pushy. 15.8kg is pretty hefty too, though bare in mind the 5404 is 15kg on its own! i haven't weighed my own wheel (HT35) but im guessing its around the 10-11kg mark, so your doing pretty well considering the strength of that wheel!

I think that somehow I pushed a little, but im almost sure I ll still be able to go by as a bicycle when I finish my build. 15.8kg its not that much if you account that the hub motor is 10kg and the tire is around 3kg...

 

[gensem]

NICE gensem!

What is the widest point on that 2.75" tire? Is it at the 2.75" tread line, or are the sidewalks wider?

I use a program called ThumbsPlus to crop/shrink my pictures to 640 x 480.

Im yet to understand the 2.75 in moped tires. I tought it was 2.75 inchs but my meter is telling me the treadline is almost hitting 3.3" wide.

I know how to resize images, but what I wanted was to let people see a small preview in low res like 640 and have the option to click on the picture for a full res, full screen picture.

 

[johnrobholmes]

Looks cool Gensem! I would have opted for a single cross lace. 19" is the smallest rim I double cross with motorcycle rims and big hubbies.

 

[gensem]

Looks cool Gensem! I would have opted for a single cross lace. 19" is the smallest rim I double cross with motorcycle rims and big hubbies.

Being the first hub motor the wheel guy did I really cannot complain. Aside the fact that he warranted me a replacement wheel if was able to break it. Yet I have to tell you that my next wheel ll probably be smaller with a thinner profile, like 1.85.

 

[johnrobholmes]

Where did you pick up the tire? Looks good!