Warren's 350 MAC mid-drive (finally) recumbent

[mi7d1]

mi7d1,

You must be running a internal gear hub in the rear, correct? I can't see how you could spin at 30 mph for 44 miles with that tiny chainring, and a normal 11 tooth cassette high gear in back.

I suspect your buddy's Stokemonkey wouldn't do any better than your rig. Hills take a huge amount of power.

jbond,

Your mid-drive idea, with a geared hub motor has me sold. I will contact cell_man about a motor...maybe this one.

http://www.emissions-free.com/catalog/i3.html

mi7d1,

What is the highest amps you are pulling? Sounds like this motor is limited to about 15 amps.

Thanks, warren

No internal geared rear hub. Just an 11-34 cassette. My bottom bracket is a Schlumpf high speed drive. http://www.schlumpf.ch/hp/hsd/hsd_engl_ausfuehrungen.htm It's an internal geared two speed bottom bracket with a 2.5 overdrive. The chain ring is 27t and in overdrive is equivalent to a 67.5t chain ring. That gives me a gear inch range of 20.6"-159.5 with a 26" rear wheel. A pedaling cadence of 80 RPM will get me ~32mph and 100 RPM would net me 40 mph.

My e-assist is not a mid-drive but a bottom bracket drive. The motor see all the gears and not just the back set. My motor controller is/was 20amp. The Mac geared motor you linked to looks close to the specs of my Crystlyte direct drive motor but less weight. With the right setup, I think you'd be happy with it.

Here's the E-S link from May 2008 http://endless-sphere.com/forums/viewtopic.php?f=3&t=4426

[mi7d1]

mi7d1,

Looks like your reduction is 16/48. According to their spec page, a C408 runs 356.4 rpm on 36 volts, no load. That means your cadence is 95 rpm at 80% of no-load. Am I figuring correctly?

Warren

With my bottom bracket drive I'm using a C'lyte 408 motor with an 18t freewheel and a 46t chain ring giving me a 2.55:1 ratio. I'm trying to run the motor at peak efficiency. I believe that would be ~260 RPM for the motor. All that was new to me back on 08. Perhaps the 3:1 of a 16/48 combo would get closer efficiency to my friends Stokemonkey.

According to my friend in an archived email, the (His) Stokemonkey uses a 407/409 two speed motor and runs a 16/48 combo.

Bill

[mi7d1]

It just dawned on me that the 2008 E-S link I posted about the e-Power Challenge was or could be misleading. That link was about when I was running a C'lyte 406 hub motor in my rear wheel with a 48v 18Ah SLA pack. In April of 2009 I was building my bottom bracket drive for the May 2009 race date. With the bottom bracket drive at the 2009 e-Power Challenge I used a C'lyte 408 motor and a 36v 20Ah pack of Headway cells. Speed wise the bottom bracket drive was slightly slower but had many benefits most of all torque and the ability to climb hills.

I won my category but wasn't the fastest one there. That honor goes to Bill Bushnell who had a socked long wheel base recumbent with a mid-drive. Bill did ten laps in 36min 1 sec



My race results from the 2009 e-Power Challenge were;

20 miles (ten laps)
43min 42sec time

I cropped a photo of my race results, hope it isn't hard to see

[Warren]

Bill,

Now I am confused. Let us say your friend is using the 409 wind of his motor. The 36 volt no-load speed is 317.9 rpm, so the 80% (most efficient?) speed is 254.3 rpm. With his 16/48 reduction, he would have a cadence of 84.8 rpm...pretty comfortable.

For you, 408 wind, 356.4 rpm no-load, 80% is 285.1 rpm. With your 18/46 reduction, your cadence would be a very fast 111.8 rpm. If you are pedaling at 80 rpm, then the motor is turning 204 rpm, 57.25% of no-load. That is closer to maximum power rpm than maximum efficiency. Perhaps that explains the difference in Wh/mile? But you should be able to beat him in a drag race! At a cadence of 80, you want a 16/57 for maximum motor efficiency.

Warren

[mi7d1]

Bill,

Now I am confused. Let us say your friend is using the 409 wind of his motor. The 36 volt no-load speed is 317.9 rpm, so the 80% (most efficient?) speed is 254.3 rpm. With his 16/48 reduction, he would have a cadence of 84.8 rpm...pretty comfortable.

For you, 408 wind, 356.4 rpm no-load, 80% is 285.1 rpm. With your 18/46 reduction, your cadence would be a very fast 111.8 rpm. If you are pedaling at 80 rpm, then the motor is turning 204 rpm, 57.25% of no-load. That is closer to maximum power rpm than maximum efficiency. Perhaps that explains the difference in Wh/mile? But you should be able to beat him in a drag race! You want a 16/57 for efficiency.

Warren

I'm interested to know where you're getting the no-load 356.4 rpm for a 408 motor. It could be that I'm not understanding but according to the ebikes.ca simulator http://www.ebikes.ca/simulator/ the 408 motor has a no-load rpm of ~290rpm. If that's the correct number than I should be targeting a 232 motor rpm and a 100 rpm cadence (that being my cadence goal)

This is all still new to me. With me about to try a new motor, it's important that I get it correct.

Bill

[Warren]

Bill,

"I'm interested to know where you're getting the no-load 356.4 rpm for a 408 motor."

From their website.

http://www.crystalyte.com/Mspecs.htm

I haven't checked that simulator yet. I would assume the company is using actual measurements, not simulations? But then, I don't understand the amps, and watts given in each row either. For instance, for the 408 on 36 volts, at 15 amps, wouldn't the watts be 540 instead of 332.524? Or maybe that is measured power out...61.57% efficiency?

"This is all still new to me. With me about to try a new motor, it's important that I get it correct."

I know there are some real wizards on this list. I wish they would speak up.

Warren

[Sturdly]

Dom Harvey had a 48 volt 408 in his BB drive, built about 4 years or so ago now. I think he also used one of the dual wound two speed versions an a later incarnation. http://www.evalbum.com/769 a pic of an early version.

[Warren]

Sturdly,

"Dom Harvey had a 48 volt 408 in his BB drive, built about 4 years or so ago now."

Wow! He did just what I had suggested. He made a left hand threaded adapter, for a southpaw freewheel.

http://www.flickr.com/photos/89372267@N ... 115596918/

Man, I wish I still had access to a machine shop.

Warren

[mi7d1]

Bill,

"I'm interested to know where you're getting the no-load 356.4 rpm for a 408 motor."

From their website.

http://www.crystalyte.com/Mspecs.htm

I haven't checked that simulator yet. I would assume the company is using actual measurements, not simulations?

Warren

Very interesting between the two I put my faith with Justin Lemire-Elmore of http://www.ebikes.ca

The parameter values that are choosen for the motor model are based on directly measured data that we have compiled from tests using a custom built dynamometer made for the task.

[mi7d1]

Sturdly,

"Dom Harvey had a 48 volt 408 in his BB drive, built about 4 years or so ago now."

Wow! He did just what I had suggested. He made a left hand threaded adapter, for a southpaw freewheel.

http://www.flickr.com/photos/89372267@N ... 115596918/

Man, I wish I still had access to a machine shop.

Warren

Thanks for posting the flickr set link Warren. I see he was also using a 13/44 combo for a 3.38:1 ratio. Perhaps I should have used a smaller freewheel like you mentioned

Bill

[Warren]

Bill,

"I see he was also using a 13/44 combo for a 3.38:1 ratio.

Which, if you use the company numbers for no-load rpm, gives him 84.2 rpm at 80%. Right where I would want to be.

"Perhaps I should have used a smaller freewheel like you mentioned"

Actually, I suggested a bigger chainring, because you can no longer buy a freewheel smaller than 16 teeth for a standard 1.375 inch diameter thread. AC Racing made a 15 tooth briefly. Dom made an adapter for the smaller M30x1 size freewheels.

Warren

[mi7d1]

Bill,

"I see he was also using a 13/44 combo for a 3.38:1 ratio.

Which, if you use the company numbers for no-load rpm, gives him 84.2 rpm at 80%. Right where I would want to be.

"Perhaps I should have used a smaller freewheel like you mentioned"

Actually, I suggested a bigger chainring, because you can no longer buy a freewheel smaller than 16 teeth for a standard 1.375 inch diameter thread. AC Racing made a 15 tooth briefly. Dom made an adapter for the smaller M30x1 size freewheels.

Warren

I just checked my parts inventory and I have an 18t freewheel and a 60t chain ring. That will get me a 3.33:1 ratio. I'll have to get the e-assist reassembled in the velomobile and give it a try.

Bill

[Warren]

Bill,

"I just checked my parts inventory and I have an 18t freewheel and a 60t chain ring. That will get me a 3.33:1 ratio. I'll have to get the e-assist reassembled in the velomobile and give it a try."

Sweet! I will be anxious to hear how it goes. It must be nice living where it is not in the 20's right now.

Warren

[MitchJi]

Hi Warren,

I'm jumping in after only reading your first post so please forgive me if what I say is something that has already been mentioned or rejected.

Marcus (http://www.pimobility.com/) used to use a drive design similar to the Hanebrink (mid-mounted hub motor). In that application he really preferred geared hub motors. Because the use the bike's gears they were running pretty close to a perfect RPM with pretty good efficiency and were much lighter than comparable DD hub motors.

[Warren]

Mitch,

"Marcus (http://www.pimobility.com/) used to use a drive design similar to the Hanebrink (mid-mounted hub motor). In that application he really preferred geared hub motors."

Yes. I read that he dropped the mid-drive to get the price down. Too bad, other than the styling now, it is just like all the other hub drive bikes.

Warren

[Warren]

Folks,

I have been in correspondence with cell_man about a 350 watt, geared, rear, MAC hub motor. It sounds perfect, except for an aluminum threaded freewheel mount. He is checking into availability of the newer version with a steel freewheel mount.

This week, I had the "opportunity" to bring home a pedelec, front geared hub, comfort bike, from work to trouble-shoot. It has a loose connection somewhere. The thing is a nightmare of possible loose connections.

It has wires running from the battery pack/controller on the rear rack, to the brake levers, to the cheap left paddle throttle, and to the pedelec sensor on the bottom bracket. Switches which may have poor contact include the two plunger type switches in the brake levers, the incredibly cheap rocker switch in the paddle throttle, and the sloppy key switch in the controller!

Also, the battery is connected to the controller by two spring loaded plungers sticking out the back of the controller! The electrical stuff on this bike are way too complicated, and way too cheap.

This experience has led me to decide to go with only a left hand, half twist throttle. Hopefully I am smart enough to figure out when to turn the power on and off.

There is no manual for this thing. It only has three fairly large wires to the motor. Does this mean it doesn't use hall sensors?

Warren

[Warren]

Not much interest in my fairly weak mid-drive I guess. But I did sort out than pedelec. One of the power wires from the key switch to the spring loaded contact plunger. The nyloc nut wasn't tight. Resistance was high enough to melt the nylon out of the nut, darken the nut, connector eyelet, and melt insulation on the end of the wire. Sanded up all surfaces, and replaced nyloc nut.

[gtadmin]

Not much interest in my fairly weak mid-drive I guess.....

Hi Warren, don't get discouraged, not everyone who read the posts feel qualified to add to the topic (like me)

Cheers mate,
GT

[TylerDurden]

Not much interest in my fairly weak mid-drive I guess.....

Hi Warren, don't get discouraged, not everyone who read the posts feel qualified to add to the topic (like me)

Likewise here. Lots of looking, eventually an enlightened member will chime in.

As for the PAS motor, if it only has three heavy wires it is sensorless... PAS motors are typically moving before power is applied, so they don't need sensors to determine the direction of rotation.

It may be helpful to edit the title of the original post to "mid drive questions"... some folks in Europe are using the smaller hubbies for mid drives (bafang, etc.). Many are cyclists, well versed in gearing for minimal assist:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=17070&start=0&hilit=

[Warren]

GT and TD,

Thanks for the encouragement. I am pretty psyched by this project. Not very exciting for a motorhead. But for a bicyclist to have a stoker as strong as Lance Armstrong, who only weighs 50 pounds, is great!

TD,

How does the motor manage to keep in sync without hall sensors? I thought that required a fancy controller. This thing has a controller the size of a pack of cigarettes.

And thanks for the great link.

Warren

[TylerDurden]

As I understand it, once it is moving the correct direction, a sensorless controller can sync from the motor's back-emf.





Edit: removed landmine. ES remains independent!

[katou]

Check out the Castle Creations line of ESC (controllers in RC world) they're tiny!! You could fit two of the littler ones in a pack of cigarettes.

Good luck, how about some pictures?

Katou

[MitchJi]

Hi Warren,

Folks,

I have been in correspondence with cell_man about a 350 watt, geared, rear, MAC hub motor. It sounds perfect, except for an aluminum threaded freewheel mount. He is checking into availability of the newer version with a steel freewheel mount.

I'd prefer the aluminum. Matt had FW adaptors machined in both aluminum and steel. The reason he had some made in steel was not that the aluminum wasn't strong enough. He said it was because with steel he had the option of removing the set-screw-shoulder (narrower overall width) and welding the adaptor to the shaft. The reason I would prefer aluminum is it is quite a bit lighter. Here's Matt's description:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=7180&p=122330

...he steel adaptor weighs 4.6 ounces. The aluminum adaptor weighs only 1.6 ounces!

The thread shoulder can be machined off allowing the set screw hub to be inside the FW thread section. That narrows the setup by 1/2 inch. But, it hides the set screws. However, in some situations, that may be desireable...

One of the three pictures:

[Warren]

Mitch,

My concern was not that the threads wouldn't hold up, but that the aluminum threaded portion might break off the cover, as apparently has happened on several different brands of hub motors. The problem has been not a large enough radius between the threaded portion, and the side cover causing stress riser cracking.

My latest idea is to use two sprockets bolted to the disc brake mounting holes, on a 350 watt, front motor. It is almost a half pound lighter, mostly from the shorter axle.

I figure I will make a couple of spacers to separate the cogs from the motor and each other...enough to allow chain clearance.

http://www.velosolo.co.uk/shopdisc.html

http://www.tomicog.blogspot.com/

I will flip the motor so the cogs are on the right side. The inner cog will be a 16 tooth for the chain running to the rear wheel. The outer cog will be a 15 tooth for the chain to the front single chainring. This is to get my cadence down to a reasonable level. A 13 tooth would be my preference, but 15 is as small as the disc brake bolt circle will allow.

To compensate for the motor running backward, I will cross the chains (figure eight) running to the crank, and to the rear wheel. Since these are long runs on a recumbent, the side load where the chain crosses is small. A short section of teflon chaintube should allow the slack side chain to deflect around the tensioned chain. It will look essentially like the normal chain run on typical recumbent.

http://www.ransbikes.com/Enduro09/Enlarge09.html

Since I want to be pedaling, any time the bike is propelled, this should be about the simplest setup.

Cell_man, Paul, must be on holiday. He hasn't gotten back to me.

Warren

[MitchJi]

Hi Warren,

My concern was not that the threads wouldn't hold up, but that the aluminum threaded portion might break off the cover, as apparently has happened on several different brands of hub motors. The problem has been not a large enough radius between the threaded portion, and the side cover causing stress riser cracking.

My latest idea is to use two sprockets bolted to the disc brake mounting holes, on a 350 watt, front motor. It is almost a half pound lighter, mostly from the shorter axle...

It sounds like it breaks due to the pounding the hub motor gets mounted in a wheel every time the bike hits a bump. Assuming its a decent quality hub, a hub in a mid-drive configuration, which isn't subjected to the same stresses should be fine (unless I'm missing something ).