tangentdave
1 kW
Here's 9.2kRPM unloaded (192kV @ 48V); 220W. If I remember right, this Astro 3210 at max speed is 40-60W on the bench.
-dave
Dave's 80:1 RC mid drive kit build log
- Thread starter tangentdave
- Start date
Here's 9.2kRPM unloaded (192kV @ 48V); 220W. If I remember right, this Astro 3210 at max speed is 40-60W on the bench.
-dave
dequinox
10 kW
I like the harmonic/cycloidal? drive... I'm a little familiar as I worked on the ATRIAS project at OSU. That robot used harmonic gear reduction in its "hip motors".
Pretty unit, can't wait to see how this works out for longevity!
Pretty unit, can't wait to see how this works out for longevity!
tangentdave
1 kW
There are two cycloidal gears inside the housing, offset for balance. These gears sit inside the tooth profile of the housing in a planetary arrangement. These two wobble gears are 4140 steel (aka Chromoly) as are the teeth on the annular gear (the housing is aluminum). The bearings inside are well overrated- the output bearing is rated for over 2,000lbs static. The unit I'm riding now shows no signs of wear, this type of gear is known for it's toughness and efficiency. The drive units are completely serviceable and come totally apart. The unit holds about 4cc of grease and maintenance means a quick shot of special grease through the fill port every few hard rides and open in up once or twice a season to wipe the old grease. This takes about an hour to remove it from the bike, pull the motor (for convenience) pop it out of the housing and wipe it down.
I've been riding on prototypes for 3 months now. These used 6061 aluminum gear faces and showed me where the design issues are by wearing faster. The steel units don't wear or get hot until you've been using over 2000W for 5 minutes or more. Less than 2000W and the unit is barely warm, and it's been hot in Seattle lately. I've been working on the shape of the tooth profile and the energy transfer to the output carrier and its making an efficient unit.
-dave
I've been riding on prototypes for 3 months now. These used 6061 aluminum gear faces and showed me where the design issues are by wearing faster. The steel units don't wear or get hot until you've been using over 2000W for 5 minutes or more. Less than 2000W and the unit is barely warm, and it's been hot in Seattle lately. I've been working on the shape of the tooth profile and the energy transfer to the output carrier and its making an efficient unit.
-dave
Thats a good point, how do you repair or rebuild the gearbox and what life does it have ? i have seen the AFT kit gears last over 5000 km and then its a cheap $30 USD set of planetary gears. The belt drive kits like LR not sure how long the belt lasts? but i am guessing they are very cheap to replace. If the gearbox is so complicated it is very important to know how long it will last and how much it costs to replace the wearing parts, i wouldnt want to be changeing a $300 USD custom hard to manufacture gearbox every 1000 km...
tangentdave
1 kW
There are two gears, both Chromoly steel, under compression stresses. Cycloidal reducers are known for their toughness, hence their use in construction equipment and industrial applications. This gear is designed to be serviceable; tools required for complete disassembly: flat blade screwdriver and a 2.5mm (m4) Allen key.
If any early adopters were to experience issues with the system, I'd like to know what's wrong so I can fix it for you and everybody else. My unit shows no signs of wear on the gearset and I'm inside that unit every couple days checking. I ride it like I hate it too, I'd rather it break with me than you. But all this said, this is why the early discount.
-dave
If any early adopters were to experience issues with the system, I'd like to know what's wrong so I can fix it for you and everybody else. My unit shows no signs of wear on the gearset and I'm inside that unit every couple days checking. I ride it like I hate it too, I'd rather it break with me than you. But all this said, this is why the early discount.
-dave
dequinox
10 kW
This is a great primer on a cycloidal drive.
A cycloidal drive is different from a harmonic drive in operation principal in that there is flexing intermediary ring called a flex spline:
Video 1: CAD animated
Video 2: real operation
A cycloidal drive is different from a harmonic drive in operation principal in that there is flexing intermediary ring called a flex spline:
Video 1: CAD animated
Video 2: real operation
ScooterMan101
1 MW
In the world of ultralights ( microlights in Europe ) they use what I believe is called a Lord Mount, They work on mounting very torquey , Vibration Intense 2 stroke motors, and they work quite well.
I do not have the time to look it up right now, anyone here fly / have knowledge of those, where tangentdave could get them ?
>
Matt[/quote]
The noise should be reduced with a isolation mount, but definitely not eliminated. He should download a spectrum analyzer for his phone and then first measure it with the unit hanging in free air, and then mounted to the frame, to see how much the frame is amplifying the drive vibration. From there you might play around with touching parts of the the drive kit to find the main source of the "irritable" sound. The goal is not to totally eliminate the sound, but reduce the level and make it more pleasant. I'm guessing couple damping pads on the two large side plates or bracing could also help, in addition to the isolation mount(s). The plates could be acting as a sound board.[/quote]
I do not have the time to look it up right now, anyone here fly / have knowledge of those, where tangentdave could get them ?
>
Matt[/quote]
The noise should be reduced with a isolation mount, but definitely not eliminated. He should download a spectrum analyzer for his phone and then first measure it with the unit hanging in free air, and then mounted to the frame, to see how much the frame is amplifying the drive vibration. From there you might play around with touching parts of the the drive kit to find the main source of the "irritable" sound. The goal is not to totally eliminate the sound, but reduce the level and make it more pleasant. I'm guessing couple damping pads on the two large side plates or bracing could also help, in addition to the isolation mount(s). The plates could be acting as a sound board.[/quote]
tangentdave
1 kW
New mounts, no twisting, no downtube clamp, frame resonance is drastically decreased. There is still a solid mount to the bike frame at the bottom bearing so some vibration comes through under high RPM.
I chose this bike as a demo 'cause of the odd downtube shape, like a rounded pyramid, point on the bottom, almost impossible to clamp to, super thin wall aluminum. I'm using a polyurethane tube over an aluminum spacer to transmit the forces to the downtube, and a zip-tie to make sure the motor stays rotated up (fancy rubber strap to follow soon). I've been through at least 4 side plate designs to get this working without twisting.
40mph, 28lbs, the ultimate commuter machine. Wheelies on thin tires kinda hurt coming down.
-dave
I chose this bike as a demo 'cause of the odd downtube shape, like a rounded pyramid, point on the bottom, almost impossible to clamp to, super thin wall aluminum. I'm using a polyurethane tube over an aluminum spacer to transmit the forces to the downtube, and a zip-tie to make sure the motor stays rotated up (fancy rubber strap to follow soon). I've been through at least 4 side plate designs to get this working without twisting.
40mph, 28lbs, the ultimate commuter machine. Wheelies on thin tires kinda hurt coming down.
-dave
adriftatsea
100 W
Rad. How noticeable is the improvement in watts per mile when switching from the Kona to roadbike?
It also looks like this resolves my worry about my shock mount interfering. Good stuff.
It also looks like this resolves my worry about my shock mount interfering. Good stuff.
tangentdave
1 kW
Put this bike together the other day, been testing the power on hills around town. The biggest efficiency killer is the throttle, it's too much fun. I'll put some commuting miles on it this week for comparison- the Kona needs constant power to keep moving, even downhill, whereas these street tires just roll and roll.
-dave
-dave
tangentdave
1 kW
dave + cameras = 
They're standard 700c wheels, both of 'em.
They're standard 700c wheels, both of 'em.
tangentdave
1 kW
All the clamps I cut for the kits are at the anodizing shop still, sorry I can't take a picture. They're essentially the same as on the website, just beefed up. However, this is the downtube interface I've been running successfully as late. The kits will get both- if people decide not to run 3000W, they won't need to think about the downtube clamp. There still needs to be a hold-up strap, especially for off-road.
That's a nice squishy polyurethane tube over an aluminum spacer, decouples the resonance well. The way the mount bracket surrounds the housing prevents the twist. The kit side plates are 1/8" 1018 steel with reinforced cross bolts. Some vibration still comes through the bottom bearing since the mount is clamped tight. It's not bad and a small price to pay to hold this much power.
-dave
That's a nice squishy polyurethane tube over an aluminum spacer, decouples the resonance well. The way the mount bracket surrounds the housing prevents the twist. The kit side plates are 1/8" 1018 steel with reinforced cross bolts. Some vibration still comes through the bottom bearing since the mount is clamped tight. It's not bad and a small price to pay to hold this much power.
-dave
tangentdave
1 kW
The Kona has been unceremoniously tossed into a corner and it's drive transplanted into a new beautiful raw Intense Tracer 275. The guys at GHYbikes are great, highly recommend.
The mass centralization improves handling quite a bit. The front end is much lighter and the bike dances over obstacles better since the weight of the drive is so near the center of gravity. Also replaced the rubber strap with an adjustable metal band so the poly downtube cushion is now the preferred mounting method- the metal band won't stretch, takes up less space and believe it or not, is easier to make.
16Ah took me 20 miles up and back Hansen Ridge yesterday with about 4000' of vertical climb after a wrong turn down a fire road. The trail was mostly 6" loose boulders (big enough to stop the bike and pitch me over the bars on the way down) which the drivetrain handles flawlessly, no dropped chains. I've kept the stock Shimano 10speed cassette and am running a 34t narrow-wide for the front chainring. Top speed is about 32mph (gearing limited) and performs great on the trail. The first three cogs aren't a good match for the motor, too much torque means you hit the end of the gear too quickly, but I did enjoy the 32t rear when I ran out of gas. The VPP suspension seems to love the torque of the motor and launches the bike forward with a twist of the wrist. The uphill boulder fields were easily tamed without use of the pedals.
-dave
The mass centralization improves handling quite a bit. The front end is much lighter and the bike dances over obstacles better since the weight of the drive is so near the center of gravity. Also replaced the rubber strap with an adjustable metal band so the poly downtube cushion is now the preferred mounting method- the metal band won't stretch, takes up less space and believe it or not, is easier to make.
16Ah took me 20 miles up and back Hansen Ridge yesterday with about 4000' of vertical climb after a wrong turn down a fire road. The trail was mostly 6" loose boulders (big enough to stop the bike and pitch me over the bars on the way down) which the drivetrain handles flawlessly, no dropped chains. I've kept the stock Shimano 10speed cassette and am running a 34t narrow-wide for the front chainring. Top speed is about 32mph (gearing limited) and performs great on the trail. The first three cogs aren't a good match for the motor, too much torque means you hit the end of the gear too quickly, but I did enjoy the 32t rear when I ran out of gas. The VPP suspension seems to love the torque of the motor and launches the bike forward with a twist of the wrist. The uphill boulder fields were easily tamed without use of the pedals.
-dave
That looks awesome Dave - I always thought that the motor would be better inside the triangle as it is protected far more than hanging off the bottom of the bike - good to see it's possible. Do you need to be more careful of your legs getting chewed though?
All the best and hope it's all going well!
All the best and hope it's all going well!
tangentdave
1 kW
If anybody is lucky(?) enough to be in Vegas Sep 15-18 for Interbike, I'll be there with the two bikes in the pics. PM me and we can set up a demo ride.
-dave
-dave
Ralith
100 mW
I continue to commute on it daily, it continues to be great. I'll get around to taking a photo or two one of these days.
adriftatsea
100 W
Archer said:
It sets the high water mark so far for 'off the shelf' mid drives. I use it for my daily commute and haven't run into anything I couldn't climb with it.
I transitioned into mid-drives from a 20s HT35 rear hub setup into a 16s GNG chain driven mid drive. In both cases it was obvious whomever produced these parts didn't actually use them everday (or at least weren't 'into it' like ES readers) ... questionable engineering choices, poor tolerances, horrible QC etc. The GNG specifically had a crankset adapter that was poorly thought out and large runout on everything that moved which made it really loud and caused chaindrops. But I lived with it since I like changing gears.
Dave's kit on the other hand is obsessively well built.
The only 'downside' is that it's kinda loud when it's not really loaded down in a high gear. Perhaps I'm overstating 'loud', but it's enough that I refrain from mashing it through our 'pedestrian only' main street and felt weird using it when people were speaking during a recent 'bike tour' group ride of local landmarks. Aside from that it's sounds kinda neat and I like it.
Anyway, while I know a sine-driven rear hub would be a better fit for my commute, I still like knowing I have an overbuilt drivetrain that can devour any hill, is realiable, and was made from mostly made in the USA components.
I'm working on a more data oriented review in the coming weeks once I get the bike gearing and such sorted.
Lurkin
100 kW
Really, really nice work. Working in finance in a company with R&D.... it takes $, time, sweat and plenty of scotch to get a finished product. Looks really good and significantly better than many of the current mid drive options out there.
I choose a bafang mid drive for my first bike for it's simplicity. It will probably need to be retired at some point and I am slowly investigating potential replacements in the meantime.
I have no astro motor experience. Are these motors ok to be run with lower power? I would be interested in a range between 500w - 1500w.
Is there a thinner version of the astro/your design? I really like the central mount option, but it's probably too wide for my application.
Is there a chain guide option? I picked in the bafang in the end because it was simple to install, quiet and most of all, discrete. If anything, its a the battery and wiring currently giving it away.
I choose a bafang mid drive for my first bike for it's simplicity. It will probably need to be retired at some point and I am slowly investigating potential replacements in the meantime.
I have no astro motor experience. Are these motors ok to be run with lower power? I would be interested in a range between 500w - 1500w.
Is there a thinner version of the astro/your design? I really like the central mount option, but it's probably too wide for my application.
Is there a chain guide option? I picked in the bafang in the end because it was simple to install, quiet and most of all, discrete. If anything, its a the battery and wiring currently giving it away.
tangentdave
1 kW
The Astro motors work great at low power. The 7 turn is most efficient at 24 amps, but using less current still means less heat. If you were to use an Astro Flight 3205, which might be well suited to what you're asking for, the width of the drive could be made half inch narrower, making the motor side 55mm wide from centerline.
There could be a chain guide- do you mean something to cover the motor chain?
There could be a chain guide- do you mean something to cover the motor chain?
Lurkin
100 kW
tangentdave
1 kW
A cover should be easy. I'm thinking a plastic piece held down by a couple screws. When we settle on what shape the side plates will be then we can work on fancying it up.
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