Dave's 80:1 RC mid drive kit build log

[brumbrum]

I've run it around 35A for minutes at a time with the 3210 and things merely get warm. It's efficient enough (and my chainring is small enough) that it can be difficult to actually push the motor harder than that without a good hill.

Ok, thanks. I just want to get any idea how the system will work off-road on rugged deep muddy puddled terrain with steep hills. I would not be using the bike on the road all that much. I am guessing it will use more amps than on a smooth surface to get around. I have since read that the 3220 was fed 60a by Dave, perhaps he can confirm this, but i am not sure how much the 3210 can handle. Here's my local terrain...

 

[Nathan]

You have no idea what you are talking about. A 3220 is 92% efficient while the cycle is around 80%. That means a 3220 can produce over twice the power of the cyclone per pound of weight. I have run 8kw continuously through a 3220 without any problems (10 kw with fan cooling).

Where did you get 92% from ? on the astro webpage lists max motor efficiency of the 3220 to be only 90%
http://www.astroflight.com/3220

Also I bet if the cyclone was run on an ESC( or FOC vector controller ) like the 3220 I bet the gap would be closer or nothing due to the improved timing accuracy vs standard ebike trapedzoidal controllers.

I don't think the difference in efficiency or power will be as much as you think in the real world when motors get hot. Even though the astro motor can run up to 200C this means that the winding resistance will be a lot higher and less efficient at these temperatures to compared to the cyclone motor with forced air cooling, so even thought it has a lower temp limit it will always run at this lower temp and hence higher efficiency point. The actual efficiency in use is more important then peak efficiency in a data sheet .

 

[macribs]

Well again you forget that heat is not an issue with the Astro motors when cooled with a fan. So resistance should not increase badly because even if the motors can take 200 degrees celcius they do not get that hot. Also Matt aka recumpance is also the man behind the Davinci drive and have worked with Astro motors for several years and have done many high performance build with Astro motors. Both ebikes, trikes, single drives, dual drives etc. Heck if you ask him for a triple setup for insane power I am sure he would fix you up nicely with peak power close to 25-30 kw.
If he claims efficiency is higher then 90% you can be sure he knows it.

 

[recumpence]

You have no idea what you are talking about. A 3220 is 92% efficient while the cycle is around 80%. That means a 3220 can produce over twice the power of the cyclone per pound of weight. I have run 8kw continuously through a 3220 without any problems (10 kw with fan cooling).

Where did you get 92% from ? on the astro webpage lists max motor efficiency of the 3220 to be only 90%
http://www.astroflight.com/3220

Also I bet if the cyclone was run on an ESC( or FOC vector controller ) like the 3220 I bet the gap would be closer or nothing due to the improved timing accuracy vs standard ebike trapedzoidal controllers.

I don't think the difference in efficiency or power will be as much as you think in the real world when motors get hot. Even though the astro motor can run up to 200C this means that the winding resistance will be a lot higher and less efficient at these temperatures to compared to the cyclone motor with forced air cooling, so even thought it has a lower temp limit it will always run at this lower temp and hence higher efficiency point. The actual efficiency in use is more important then peak efficiency in a data sheet .

Dyno charts used to be provided with each 3220. The best I have ever seen was 94.4% efficiency.

Efficiency has to do with lamination thickness, magnet gap width, copper full, etc, etc, etc.

I stand behind my statement; you don't know what you are talking about.

 

[Thud]

Nathan, study your charts.
Your reading a single chart for the 3220.....(which is complete overkill on the reduction unit this thread is about)

all the motors in that chart are loaded to their 90%
The 4 turn motor is drawing 96 amps & is delivering 5+ horspower at 90%.
The same motor is delivering 93% eff. at a 43amp load.

Regarding heat, fan cooled or not. Its apples & oranges.
The industrial Astro's were developed in the early 80's for the 1st forays into UAV for the us military. They had to be sealed to survive desert dust & the magnets had to deliver in 200C heat.
That is why they cost what they do..

By any metric you measre motor performace, the astro is superior. The neodyninum in the cyclone will begin a death song @ 175f (80c) this is way before copper loss & resistance start to effect motor performance
Thats not saying the cyclone is garbage...for what we're doing here, both are more than capable. Horses for courses.

As for sinusodial controll on the astro? AFAIK they are wound to deliver a trapazoidal bemf wave form to get the most efficancy from the lightweight controllers of the time....i dont know if going sinusodial will show any measurable sound reduction from tangent daves kit.

Oops, typed too long. Recumpence has already answered.
Take it for what its worth.

 

[tangentdave]

I just want to get any idea how the system will work off-road on rugged deep muddy puddled terrain with steep hills.

35A continuous is easy peasy, all day long. 35A pretty much means you're in about the 15t rear cog with a 38t front going up a steep-ass hill without helping much. 35A could also mean the 22t cog, 38t front, going up a nasty steep boulder hill like a dirt bike, lifting the front when you want and popping over the square edges with the extra 30A of overhead. Or 35A could mean an axle deep uphill mud rut at 10mph without pedaling.

I use 35A basically constantly on the road bike and the drive might be warm. The real world continuous rating of this system is 1750W. (35A@50V)

Website updated.

-dave

 

[brumbrum]

Thanks for answering, appreciated.

 

[tangentdave]

[youtube]F9lML1AqV24[/youtube]

stinky. 40t front chainring into my 4sp cassette 24/20/15/11t. This was using the 12S LiPo pack, 16Ah, which lasted about an hour fifteen when ridden like the video. This was full-on/off riding, not the most efficient, but quite fun. Always wear your helmet.

-dave

 

[Phife]

That sounds pretty good, much quieter than I was expecting after the other videos. Cant wait to try one of these out!

Thanks for all your work Dave!

 

[StinkyGoalieGuy]

That torque looks amazing and it would be a blast to ride. It's much quieter than before but it still does sound like a gasser. Regardless, still an awesome product!

 

[Warren]

Dave,

As Matt mentioned earlier in this thread, the only problem with your drive is putting that much power through a standard bicycle drive. I see you have figured out that 4 gears is plenty for any foreseeable terrain. I would just add my previous posting for your consideration.

https://endless-sphere.com/forums/viewtopic.php?f=28&t=72411#p1093757

Warren

 

[Warren]

Again, none of this is rocket science. The strength, in tension, of a standard bicycle chain is plenty. The problem is pressure between rollers and teeth. By going to larger numbers of teeth you reduce load per tooth in direct proportion. By doubling the width of the cogs, you halve the pressure per square inch of rollers against teeth.

 

[tangentdave]

Yes, bigger power means bigger stresses, that's kind of what I'm after. Even a cheapo bike chain has a breaking strength of 2000lbs, we're ok there. I've been running a Shimano cs-hg300 9 speed (11-28t) without issues and the stock Shimano Deore 11sp on the Intense works like it should. The 4speed in the video is only for the wheelset currently on the bike- the ratios are a bit too far apart.

I'm inclined to say I want this much power, so the rest of the components need to hold the power. Bike components do hold it, they're usually as thin as possible and so wear faster. So be it, still waaay less maintenance than a dirt bike. I think I paid $15 for the cassette and another $15 for a chain? If we make high-power ebikes and need beefier components, somebody will see an opportunity and sell us what we need. In the meantime, I'm gonna ride hella fast and replace what I need to to keep doing it.

-dave

 

[jk1]

In that video it sounds a lot quieter then the first ones I have seen but you haven't changed anything really in the design ? Normally the gearbox or motor are the noisiest and they are the same ? So I think it has to do with the distance you have recorded it as noise drops very quickly with distance. Can you do another video like most people do with the camera on the bike as that is the noise people will here when they ride it in the real world.

Also for the DBA measurements on the phone the best way to do this is at a certain distance like 0.5meters from the BB bracket to simulate worst case of going past a pedestrian on the footpath full power and what would they hear ? easiest way to do this is with the wheel off the ground and brakes on and full power to simulate full load and see what the DBA is at 0.5m.

 

[tangentdave]

to simulate worst case of going past a pedestrian on the footpath full power and what would they hear ?

Horses for courses, right? The point of 4000W on the bottom of your bike is to ride the motor. The sound enhances the experience of riding the motor, just like a big moto. It's satisfying. I'll turn it down to 500W and get a sound measurement in a bit.

I lost that crappy Sony helmet cam and the weather is a bit, Seattle-ish right now. My $65 Turnigy helmet cam should be here by the time the weather dries out. Then I'll get you a vid of what this minimoto can do.

-dave

 

[joostj]

Ordered my kit this week. I want to thank Dave for making custom brackets for my unusual frame. (s-bend and linkage under the BB).
I went for some upgrades;
-3215 motor
-HV120 esc
-22t freewheel on the motor.
This takes it to about 60:1.......170 rpm max at the crank.
I will report back on my thoughts on the kit with my limited ebike experience. 1st post/1st ebike

Joost

 

[brumbrum]

Wow, that's a nice kit to start ebiking with, i am sure you will be happy with it.

I must admit, i do rather like the sound it makes, but unfortunately i know for sure that other trail walkers will find it obnoxious

 

[Phife]

I'll turn it down to 500W and get a sound measurement in a bit.

I lost that crappy Sony helmet cam and the weather is a bit, Seattle-ish right now. My $65 Turnigy helmet cam should be here by the time the weather dries out. Then I'll get you a vid of what this minimoto can do.

-dave

I'd love to hear what it sounds like at 500-1000w, If it can be pretty quiet at those speeds then I would have no issues passing people "quietly" at low power and still have another 1000+w left to play with when im out away from the other bikes and walkers.

 

[Ralith]

I'd love to hear what it sounds like at 500-1000w, If it can be pretty quiet at those speeds then I would have no issues passing people "quietly" at low power and still have another 1000+w left to play with when im out away from the other bikes and walkers.

The noise is really proportional to the RPM, so if you're at a sufficiently high gear, or just moving slowly, it is indeed pretty stealthy. As Dave's observed, the noise is something of a self-enforcing safety measure--if you're loud enough to draw attention, then you're probably moving fast enough that stealth would be unsafe, and the converse applies just as well.

 

[StinkyGoalieGuy]

I'd love to hear what it sounds like at 500-1000w, If it can be pretty quiet at those speeds then I would have no issues passing people "quietly" at low power and still have another 1000+w left to play with when im out away from the other bikes and walkers.

The noise is really proportional to the RPM, so if you're at a sufficiently high gear, or just moving slowly, it is indeed pretty stealthy. As Dave's observed, the noise is something of a self-enforcing safety measure--if you're loud enough to draw attention, then you're probably moving fast enough that stealth would be unsafe, and the converse applies just as well.

But the idea with these Astro 32XX motors is to try to keep them at high RPM and gear down for the torque. If I'm climbing an ultra steep trail, I would want to be running full RPMs from the motor, but use my biggest cog on my cassette so I'm moving at 10MPH or so. If I sound like a gasser as I'm passing the folks who are slogging up on their granny gear, that's going to be a good way to draw lots of unwanted attention.

 

[tangentdave]

I'm moving at 10MPH or so. If I sound like a gasser as I'm passing the folks who are slogging up on their granny gear, that's going to be a good way to draw lots of unwanted attention.

We all want the whole cake. But we should acknowledge what we're doing, there's nothing wrong it. e-MTBs don't tear up the woods, they're not obnoxious. Using a power assist is using a power assist, and that's fine. I hate pedaling, I love riding. The MTB trails across from the shop are off limits for testing cause there's people jogging and walking dogs, it's the intent of the trail we need to respect. So, the MTB trails across the street are for going like 10mph, at most, like I were pedaling. At comfortable climbing pedal speed the drive is in the meat of the powerband, the Astro is spinning like 5kRPM. You can easily pass people without them noticing at all.

Where I test and ride is where the drive really has to work, where it's ok to ride 30mph or out in the real mountains, the national forests where I don't bother anybody. So much fun.

 

[aCeMadMod]

ok here's what we have who is better a plian Idiots or drunk idiots and who would be safer one ? on a bike stop pick on dave kit . trolling

https://www.youtube.com/watch?v=7XvV9hbGSUQ

https://www.youtube.com/watch?v=GH6woyL8W4E

 

[StinkyGoalieGuy]

ok here's what we have who is better a plian Idiots or drunk idiots and who would be safer one ? on a bike stop pick on dave kit . trolling

https://www.youtube.com/watch?v=7XvV9hbGSUQ

https://www.youtube.com/watch?v=GH6woyL8W4E

I'm not trolling or picking on Dave. As someone who wants to buy this drive, it's fair to ask questions to know what to expect and state my observations. This is a compact and well executed reduction drive for these motors. I have had a taste of the power of the Astros and also the quiet of the Bafangs BBSX kits. Now I want the combination of both. But that doesn't exist.

I don't think I have offended Dave, but my apologies if I have. It was not my intention.

 

[tangentdave]

These questions are totally fair. I'm working on a better way to answer them, and the commercial side of this endeavor wants to know what you guys think and want. I invited the discussion with that first shitty video. It don't sound like a can of bees no more.

The drive ain't zero silent. You can use it to meander past trail walkers and they wont even know. This is big appeal to me as well, cause I don't ride balls out all the time and maybe when I'm in a place I shouldn't be balls out I see an opportunity for fun with big power without offending anybody.

We're still figuring where to ride these things. I think we'd be missing a huge opportunity to get cars off the road if we don't allow the use of ebikes on trials and bike paths, even high power drives like this one. The big trail here in Seattle is the Burke Gilman trail, paved, multi use, 15mph speed limit. I should be able to pedal my moped at less than the speed limit until I turn off and go up the stupid steep hills on the way home from work. Or maybe that dangerous overpass at the end of the bike path doesn't have a bike lane, and that's kept you from riding to work.

I guess I'm struggling to say the sound isn't offensive, its just that riding with a motor is something new; lots of people have a hard time figuring out what's already here. As Ralith points out, if the drive is loud enough to catch your attention, you're moving somewhere fast. Wide open down the paved street its as loud as my soft tubeless tires humming at 30mph. Pedestrians are thankful, not pissed. On a slow bike lane, the sound is a non starter. If someone gets pissed, its because they're picking a fight.

-dave


edit: like the video shows, nobody cares. People were everywhere when I was filming and when they do notice, they want to know what 'it' is. Screwing around in the park is basically riding a skateboard in an empty parking lot- only the security guard cares.

 

[brumbrum]

ok here's what we have who is better a plian Idiots or drunk idiots and who would be safer one ? on a bike stop pick on dave kit . trolling

https://www.youtube.com/watch?v=7XvV9hbGSUQ

https://www.youtube.com/watch?v=GH6woyL8W4E

I am sure Dave needs no help or sympathy holding his own on here. Like said above by another Forum user, i personally am only asking questions and making comment as i have a genuine interest in investing my hard earned money into this kit. At present it's still in early development so people like myself are going to be cautious considering it. As Dave as said, people want the whole cake, and this kit is ever so nearly it(for me anyway), but there are ALWAYS trade offs with differing kits and options. It is just about finding the right solution by swaying between what the heart wants and what the head needs. I myself am a 42 year old high school teacher who loves riding in the dirt here in Wales up rugged woodland and mountains. I hate weight on bikes and love acceleration over top speed, but if i got pulled by the law with this kit, i would likely lose my driving licence, and likely get in trouble with my employer, so stealth is something important to me. I know this sounds a bit paranoid, but a chainsaw/motor sound in the local woods where i am from is going to alert the farmers and ramblers alike. For me, that's a problem. So that is why at present i ride heavy hub motors with heavy battery packs and i may continue to, as this is a sacrfice i have to make to go unnoticed. If this kit was even 400 miles away from me somewhere in the U.K i would be banging at Dave's front door demanding a test drive, but alas, all i can go from are video clips, photos, and very few comments made by the few people who have actually purchased so far.