recumpence
1 GW
12-C said:Beauty of a build!
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
The pedal drivetrain could never handle that much power.
Dave's 80:1 RC mid drive kit build log
- Thread starter tangentdave
- Start date
The pedal drivetrain could never handle that much power.
aCeMadMod
1 kW
Beauty of a build!
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
yes i ask dave time of ask did not seem want to help get parts made for dual 3220 motor rc Tangent setup .
i can be done, i have all the parts just few to modding
hope hopeful dave will change his mind,
thank you all
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
yes i ask dave time of ask did not seem want to help get parts made for dual 3220 motor rc Tangent setup .
i can be done, i have all the parts just few to modding
hope hopeful dave will change his mind,
thank you all
recumpence
1 GW
aCeMadMod said:Beauty of a build!
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
yes i ask dave time of ask did not seem want to help get parts made for dual 3220 motor rc Tangent setup .
i can be done, i have all the parts just few to modding
hope hopeful dave will change his mind,
thank you all
I'm telling you, absolutely positively no way on Earth the pedal drive system could handle that much power. Absolutely no way at all. Also, with that much power there's no reason to have multiple gear ratios. A direct drive to the rear wheel is the only system that would handle that much power and as I said you don't need multiple gear ratios for so much more.
adriftatsea
100 W
Any feedback on this new gearbox from SRI, the 'archimedes drive':
https://www.youtube.com/watch?v=zoaHeamUqBE
Think this is any easier to manufacture (the one using ball bearings demo'd in the clear acrylic) or hold up to ebike abuse?
Anyway, my kit has seen near-daily use for over a year without major incidents.
https://www.youtube.com/watch?v=zoaHeamUqBE
Think this is any easier to manufacture (the one using ball bearings demo'd in the clear acrylic) or hold up to ebike abuse?
Anyway, my kit has seen near-daily use for over a year without major incidents.
recumpence said:12-C said:Beauty of a build!
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
The pedal drivetrain could never handle that much power.
That was my first thought, but I wondered if there was anyone mental enough to try it
recumpence
1 GW
12-C said:recumpence said:12-C said:Beauty of a build!
Dare I ask if there is anyone with a dual astro setup of this reduction?
Sorry had to...
Is there any way to do that?
The pedal drivetrain could never handle that much power.
That was my first thought, but I wondered if there was anyone mental enough to try it
It is not so much having the nerve to try, it is the fact that a derailer chain will not handle the torque. It would skip and break.
wyvernwaddell
1 W
I see that my new baby is in the mail-once it shows up I'll start posting build pics and stuff-I expect this is going to be wonderfully fun! Dave has been great helping me get it all figured out and, while I won't be pulling wheelies on a Yuba Mundo (I think the frame is too long for that), I expect I'll be zipping along quite nicely. THANKS!!
litespeed
100 kW
That looks nice and light.
Tom
Tom
tangentdave
1 kW
Torque, too much.
For a 50V wind, the 7turn 3210 makes 8in-oz of torque per amp, the 4turn 3220 is 8.5in-oz. Let's use battery power for calculations since we don't have accurate insight to phase current. At 50V, 3kW will produce 8x60amps= 2.5ft-lbs motor shaft torque, then 2.5x(64:1)= 160ft-lbs into the crankset. For reference, I weight 160lbs, cranks are 6.5 inches on average, so my weight generates 87ft-lbs (only when the cranks are horizontal). The 40:1 internal is best paired with a 20->32t chain reduction for an overall motor->crankset of 64:1. The 20:1 internal ratio is best paired with a 16->32t secondary, so 40:1 motor->crankset.
The 3220 will run at 3kW all day. So, we can push it to 6kW peak. 6kW run through the 20:1 then 2:1 generates a calculated 212ft-lbs at the crankset (120amps, 8.5in-oz/amps, 40:1). 6kW run through the overall 64:1 can make 340ft-lbs, that's too much to be useful unless you have a 100t front chainring. With that much power on tap you'll want to ride the motor, so more RPM in each gear is beneficial. The lower reduction 6kW kit can still act as a commuter pedal assist just fine, use a tiny amount of throttle, then when you see that fun looking ditch you pass every day...braaaap, the power is still there, you hooligan.
-dave
For a 50V wind, the 7turn 3210 makes 8in-oz of torque per amp, the 4turn 3220 is 8.5in-oz. Let's use battery power for calculations since we don't have accurate insight to phase current. At 50V, 3kW will produce 8x60amps= 2.5ft-lbs motor shaft torque, then 2.5x(64:1)= 160ft-lbs into the crankset. For reference, I weight 160lbs, cranks are 6.5 inches on average, so my weight generates 87ft-lbs (only when the cranks are horizontal). The 40:1 internal is best paired with a 20->32t chain reduction for an overall motor->crankset of 64:1. The 20:1 internal ratio is best paired with a 16->32t secondary, so 40:1 motor->crankset.
The 3220 will run at 3kW all day. So, we can push it to 6kW peak. 6kW run through the 20:1 then 2:1 generates a calculated 212ft-lbs at the crankset (120amps, 8.5in-oz/amps, 40:1). 6kW run through the overall 64:1 can make 340ft-lbs, that's too much to be useful unless you have a 100t front chainring. With that much power on tap you'll want to ride the motor, so more RPM in each gear is beneficial. The lower reduction 6kW kit can still act as a commuter pedal assist just fine, use a tiny amount of throttle, then when you see that fun looking ditch you pass every day...braaaap, the power is still there, you hooligan.
-dave
aCeMadMod
1 kW
hi dave , you say now ,, tooo much torque with 4 turn 3220 ,,
just about when i done, with fan cool deta 6 turn 3220 , and makeing costom hub for ebike, with your kit,
just need help for the right gearing, my frame not like any other i know with your kit, i was picking old gearbox 40.1 due it teeth alot stronger
i just got c.a wire up , just stunt not right can't limt amps to set hight and low
will this be too much torque for the rear swing amy of the frame, ?
thank you all 8)
just about when i done, with fan cool deta 6 turn 3220 , and makeing costom hub for ebike, with your kit,
just need help for the right gearing, my frame not like any other i know with your kit, i was picking old gearbox 40.1 due it teeth alot stronger
i just got c.a wire up , just stunt not right can't limt amps to set hight and low
will this be too much torque for the rear swing amy of the frame, ?
thank you all 8)
tangentdave
1 kW
The shunt does more than limit battery current, it lets us use 'Current' as the control mode for the throttle rather than 'Pass-thru'. With the CA in 'current' mode, the throttle is mapped to the battery current and we can sharpen the throttle ramps and increase the gain as high as we can to get the most response out of the system while still have a very precise and easy to control throttle. Pass-thru responds like a standard RC throttle where the ESC applies full power when moving between throttle commands (marginally un-ridable).
Match the battery voltage to the 6turn motor- without 10k motor RPM, the 40:1 reduction might be slow without a giant front chainring.
-dave
Match the battery voltage to the 6turn motor- without 10k motor RPM, the 40:1 reduction might be slow without a giant front chainring.
-dave
I think this drive is really sweet. I live how compact and simple it is. The one drawback I see is how loud it is. Although, some people say it's really loud and others don't. I guess that's a relative term. And some people like the noise. Ive had the cyclone with noise shroud from AFT. It was really sweet but a little too loud for me.
Does anyone know how much louder it is compared to BBSHD?
Does anyone know how much louder it is compared to BBSHD?
tangentdave
1 kW
A steel gearbox is the only way I've found to provide the robustness, efficiency and power handling in such a small package. The tradeoff is gearbox sound, which is on par with a cyclone gearbox as far as sound level (Eco Bike Adventures has a fleet of cyclone bikes, several riders mentioned they preferred the sound of the Tangent over the cyclone gearbox). It is relative though, at 500W it's like a freewheel, at 2500W you're moving/accelerating too fast for people not to assume a motor is involved, and at this power level the drive is usually mistaken for knobby tires on pavement.
I've never actually ridden a BBSHD though, just the little one.
-dave
I've never actually ridden a BBSHD though, just the little one.
-dave
recumpence
1 GW
Sound is truly relative. I have gotten to the point that I purposely "Engineer in" the sound I am looking for. I do not add sound. However, if changes can be made to alter the type of sound or frequency of that sound, I do my best to engineer the sound the way I like it. That being said, I prefer a purposeful sound. If a design has inerrant sound, so be it. Again, I try to focus that sound the way I want it (nothing artifical), but I like being able to hear what is going on in a mechanical system.tangentdave said:
Matt
ElectricGod
10 MW
Just cheap chain vs good chain is going to sound significantly different. And of course since this mid-drive kit uses all bike chain, that comes in a variety of grades. I'm sure what one person uses as compared to another really effects noise levels. Also, it would be difficult to make the elipses use helical teeth to make the gearing quieter. It would add some width, but belt drive would make things quieter too.
tangentdave
1 kW
Same here. I've tried a hundred different pitch angles and gear profiles to get this growl. Different tolerances here and there, more backlash, less backlash, no backlash, more pins, lighter gears, thicker grease, thicker ring gear; they all have an effect. End of the day, we're reducing 10-12kRPM to 250 and generating over 100ft-lbs of torque in an inch of space with only 3lbs of gearbox that's so tough nobody has managed to break one*. Other trail goers seem to prefer hearing me 30ft away when I'm moving at 30mph, but I've heard good things about the BBSHD if total silence is your priority.
*We've broken 4 or 5 high speed bearings out of 50 kits, I suspect from lack of break-in procedure, which I ask everybody to do now. These bearings have always failed almost immediately and their replacements haven't yet. These bearings are 6806 series, same as the outboard BB's, available in most bike shops and I can swap them out in 20 min with a screwdriver.
-dave
recumpence
1 GW
tangentdave said:
It seems like 10 to 12k gives the best sound (motor sound). I have one drive running over 13,000 rpm and it is a touch high pitched. 12k is the ideal max rpm from a sound perspective.
Matt
Hey Dave and everyone else who might have knowledge on this:
Can you tell us what your experiences with the turnigy graphene lipos has been? Really there is little solid information on it regarding e-bike use and with 120a peak 18650 just doesn't cut it weightwise from my calculations? Did the 12s instead of 14s make much of a difference to you?
Thanks!
Can you tell us what your experiences with the turnigy graphene lipos has been? Really there is little solid information on it regarding e-bike use and with 120a peak 18650 just doesn't cut it weightwise from my calculations? Did the 12s instead of 14s make much of a difference to you?
Thanks!
tangentdave
1 kW
I haven't used the graphene cells yet, only the Multistar packs. Higher C rate is always beneficial for performance.
I recommend 14s/52V packs because that's the most power we can run through the tiny Castle ESCs. There's about 15% more oomph in a 14s setup than 12s for the same current level, but we can easily adjust the system to use a 12s pack by stepping down the Astro turn count by 1 (3turn 3220 or 6turn 3210). Building a 4s+4s+6s=14s LiPo pack only needs two series connections and no soldering, one more step than a 6s+6s=12s, but 15% is 15%.
Also, my experience, I never see max current draw and most situations don't need it. The bike cassette/derailleur multiply the drive's torque (lowering current draw) in all but the highest speed situations. If your current draw is high, downshift and wheelie up the hill.
Been riding on a 3turn 3220 in the Zerode, still think I prefer the 4turn but it's subjective. Both are run 52V/100A limit. Yes, I could increase the max battery amps for the 3turn, more power isn't really needed though, just experimenting in how we apply it. The 3turn runs up to about 12kRPM, 62.5ft-lbs @ motor freewheel (100A calculated), 4turn is 9kRPM, 88ft-lbs.
-dave
I recommend 14s/52V packs because that's the most power we can run through the tiny Castle ESCs. There's about 15% more oomph in a 14s setup than 12s for the same current level, but we can easily adjust the system to use a 12s pack by stepping down the Astro turn count by 1 (3turn 3220 or 6turn 3210). Building a 4s+4s+6s=14s LiPo pack only needs two series connections and no soldering, one more step than a 6s+6s=12s, but 15% is 15%.
Also, my experience, I never see max current draw and most situations don't need it. The bike cassette/derailleur multiply the drive's torque (lowering current draw) in all but the highest speed situations. If your current draw is high, downshift and wheelie up the hill.
Been riding on a 3turn 3220 in the Zerode, still think I prefer the 4turn but it's subjective. Both are run 52V/100A limit. Yes, I could increase the max battery amps for the 3turn, more power isn't really needed though, just experimenting in how we apply it. The 3turn runs up to about 12kRPM, 62.5ft-lbs @ motor freewheel (100A calculated), 4turn is 9kRPM, 88ft-lbs.
-dave
Microbatman
1 kW
Some info about Graphene Batts
https://www.rcgroups.com/forums/showthread.php?2592234-Turnigy-Graphene
https://www.rcgroups.com/forums/showthread.php?2592234-Turnigy-Graphene
tangentdave
1 kW
Lots in the works, quick update.
Torque sensing PAS is compatible with the 3kW kit, it's fantastically evil, the most sadistic trainer ever. The harder you work, the harder it works, only the drive never gets tired...
The bike is an Intense Tracer 29er, ultra short 150mm cranks and big wheels give lots of ground clearance. PAS functionality is provided via THUN torque sensing BB and Cycle Analyst, slower throttle ramp settings vs throttle-only kits make freewheel engagement smooth. This bike is set up to only engage the motor when pedaling harder than 60W so it really does ride like a normal bike.
The 3-position switch allows PAS adjustment on-the-fly, off/1.5x/3x assist are my personal settings, and of course the thumb throttle still has access to the full 70A at any time. When playing around as a legal ebike without throttle, the battery pack can be as small as 12s 5Ah (think Luna's Mighty Mini cubes, we only need 30A) which I toss into a belt pouch. With assist set to 1.5x, 5Ah is good for almost 20 miles as hard as you can ride. The PAS is responsive, shifting is not an issue and you quickly become accustomed to how/when the power engages. The THUN BB senses torque only on the left crank so keep the right pedal forward and use it to start pedaling and the system engages as the left crank comes down, very intuitive. I really like having the ability to quickly switch off the PAS for tricky or nasty downhill sections too.
-dave
Torque sensing PAS is compatible with the 3kW kit, it's fantastically evil, the most sadistic trainer ever. The harder you work, the harder it works, only the drive never gets tired...
The bike is an Intense Tracer 29er, ultra short 150mm cranks and big wheels give lots of ground clearance. PAS functionality is provided via THUN torque sensing BB and Cycle Analyst, slower throttle ramp settings vs throttle-only kits make freewheel engagement smooth. This bike is set up to only engage the motor when pedaling harder than 60W so it really does ride like a normal bike.
The 3-position switch allows PAS adjustment on-the-fly, off/1.5x/3x assist are my personal settings, and of course the thumb throttle still has access to the full 70A at any time. When playing around as a legal ebike without throttle, the battery pack can be as small as 12s 5Ah (think Luna's Mighty Mini cubes, we only need 30A) which I toss into a belt pouch. With assist set to 1.5x, 5Ah is good for almost 20 miles as hard as you can ride. The PAS is responsive, shifting is not an issue and you quickly become accustomed to how/when the power engages. The THUN BB senses torque only on the left crank so keep the right pedal forward and use it to start pedaling and the system engages as the left crank comes down, very intuitive. I really like having the ability to quickly switch off the PAS for tricky or nasty downhill sections too.
-dave
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