Next project RC build, looking for advice...

[damcard]

I have learned a lot from my cyclone bike. I am looking for advice on my next build. Here is what I am thinking about doing.

A new Giant Trance mountain bike. It has about 5" of front and rear suspension travel. I will ebay off the front crank and rear hub/gearset. In place, I will use a Shimano Alfine 8-speed internal geared hub. I am thinking a Matt single stage belt drive at 5/1 reduction mounted to the frame inside the front triangle above the shock with an Astro Flight 3220. I am not sure of the ratio yet (suggestions), but use #25 chain from the drive unit to the bottom bracket. I do not need a freewheeling sprocket on the drive. I will remove the pawls from the bottom bracket freewheel to completely disconnect the cranks from the front chain rings and turn the bottom bracket into a simple jack shaft. Later, I plan to put a sprocket on the left crank arm to drive a small generator, but that is after it is on the road. Then use the granny sprocket on the front chain ring to the Alfine hub using normal bike chain. Again, I am unsure of the ratio. Has anyone mounted a large chain ring to the Alfine hub? That will give three stages of reduction plus the 8 speed hub for a nice wide range. I will be using this bike mostly on paved surfaces. Some times I will pull my boy. I have one of those half bikes that attach to my seat post, so I need a pretty wide gear range. Again, for the motor I was thinking the Astro Flight 3220. But, I am really unsure about the motor. The 8150 looked good too. I thought the 3220 would do better with the heat, but I have no experience here. My cyclone gets pretty hot and I was concerned the little rc motor will have issues. I don't know how much power at 5/1 Matt's single stage drive will take. For batteries, I will go lipo with a Castle Creations HV-140 controller. I am unsure as to the number and size of lipos.

Here is a really poorly done windows paint rendering of the bike and motor layout.

I don't have any of the parts yet, and all of this can change based on your feedback. But to sum up, Giant Trance bike, Matt single stage belt drive to bottom bracket with #25 chain. Alfine 8-speed hub. I need to decide on the motor, sprocket ratios for the second and third stage, and the number of lipo cells. I want to be able to attain 45mph on the flats. I would rather gear for more acceleration than speed above that. I can get 35 now with my 1000watt cyclone kit.

Any suggestions?

 

[recumpence]

The belt drive is good for about 4kw. If you are staying under that number, my single stage will be fine. Above that, I can set the drive up for #25 chain primary. Also, I can set it up for #25 output sprocket (non-freewheeled) or a freewheel adaptor.

The 3220 is way overkill for most situations. But, it is truely a beast and will give you your 45mph with major wheelie snapping pull. I can supply you with the drive, the motor, and even the HV140 programmed for EV use.

Bear in mind, you will need to work out mounting the drive to your frame. I will eventually be manufacturing round tube frame mounts. But, I do not have them made yet (modelled and prototyped, but not produced).

Other than that, you can expect somewhere around 15 Wh per mile at 20mph with a good RC setup. At 45mph, I would say you would be around 30 or 35 wh per mile.

I would recommend 12S 15ah minimum for your pack. 20ah would be best, though. That pack would handle the power and give good range while only weighing 13 or 14 pounds.

Matt

 

[swbluto]

Other than that, you can expect somewhere around 15 Wh per mile at 20mph with a good RC setup. At 45mph, I would say you would be around 30 or 35 wh per mile.

.... It's not a recumbent.

With normal bikes, it seems the going average is 20-25 wh/mi. at 20 mph with little to moderate pedaling to 55 - 70 wh/mi. at 45 mph with no pedaling.

 

[MitchJi]

Hi,

With the Alfine I think 4kw with a 3210 or 8150 will probably be sufficient and a belt 1st stage will be quieter.

I don't think you need 3 stages plus an Alfine with a 3210 or a 8150 or particularly with a 3220. Why not go directly from the first stage to the right rear of the Alfine? Something like Gary's build but with 2 stages instead of 1:
http://endless-sphere.com/forums/viewtopic.php?f=28&t=12267

 

[recumpence]

Other than that, you can expect somewhere around 15 Wh per mile at 20mph with a good RC setup. At 45mph, I would say you would be around 30 or 35 wh per mile.

.... It's not a recumbent.

With normal bikes, it seems the going average is 20-25 wh/mi. at 20 mph with little to moderate pedaling to 55 - 70 wh/mi. at 45 mph with no pedaling.

I am quite aware it is not a recumbent. I am talking from upright biking experience. If built properly these numbers are typical for an RC build. Heck, even with a hub motor, 40mph is about 40wh per mile. I have seen motorcycles get 60wh per mile at 40 to 45mph.

I cannot say anything right, can I? :?

Matt

 

[swbluto]

I cannot say anything right, can I? :?

Matt

You can. There was the other 80% I didn't critique, and I don't critique 90+ % of your posts. Don't feel alone, I occasionally critique and correct my own posts when I spot errors.

I am quite aware it is not a recumbent. I am talking from upright biking experience. If built properly these numbers are typical for an RC build. Heck, even with a hub motor, 40mph is about 40wh per mile. I have seen motorcycles get 60wh per mile at 40 to 45mph.

And, 40 mph at 40 wh/mi. would be impressive. That would be pretty awesome if that could be achieved - that implies I won't need as much battery capacity to get the range I desire in an electric moped/scooter as I thought I would. I do only talk from my experience at 27 mph (crystalyte 407 @ 83% motor efficiency, wh/mi. obtained from CA), some rough simulations, some quickey physics and what I've seen on the board. I'm sure there are some combinations that might generate such an astounding number, like Louis Armstrong pedaling power and a low riding bike, or a very aerodynamic riding position or a fairing.

If you know of a specific example of "normal bike riding" combinations that is so wh/mi. efficient, please point them out. I think I may have something to learn.

I think I've spotted one underlying difference in our assumptions between your numbers and my numbers. I assumed there was no free-wheel whereas a "good drive" includes the free-wheel, and that usually increases the wh/mi. efficiency. I'm not sure how much an improvement in the wh/mi. that would be, but I'm suspicious of it improving the wh/mi. figure by 30% at 45 mph.

(As a quick irrelevant example, my electric scooter consumes 40 wh/mi. at 25 mph. That's extremely bad, I know. It probably has to do with the pulley rubbing and the awful aerodynamics of a standing person.)

 

[12p3phPMDC]

I have no idea how strong Louis Armstrongs pedaling ability was
He could blow the hell out of a trumpet though...

:lol:

 

[swbluto]

I have no idea how strong Louis Armstrongs pedaling ability was
He could blow the hell out of a trumpet though...

:lol:

On his quick specially designed bike, he could continuously maintain 30 mph or about 500 watts.

On one of our ebikes in a "usual" riding position, I'd imagine that'd drop to about 20-25 mph. :lol:

 

[12p3phPMDC]

On his quick specially designed bike, he could continuously maintain 30 mph or about 500 watts.

On one of our ebikes in a "usual" riding position, I'd imagine that'd drop to about 20-25 mph.

I think you mean, he could hit a High C on his custom large bore trumpet with about
100 dB sound power at 20 feet away and part your hair at the Newport Tour de Jazz...

 

[damcard]

I don't think you need 3 stages plus an Alfine with a 3210 or a 8150 or particularly with a 3220. Why not go directly from the first stage to the right rear of the Alfine?

I was thinking I would go with three stages to cut down on noise with the belt first stage. If I went with two stages plus the Alfine, where the motor turned the bottom bracket chain ring directly similar to my cyclone, then the second from the bottom bracket to the Alfine with a large sprocket would the noise level be significant? I could machine a plate that would be sandwiched between the bottom bracket housing and the spindle's retaining nut. All the bottom brackets I would use are 68 mm. I could get a 73 mm bottom bracket set and use a 5 mm aluminum plate with a hole the same diameter as the bottom bracket housing. I could then mount the motor to that plate and have a setup similar to a Harley's primary. I considered this before, but was concerned the chain in the primary would be too loud. That is the case in my cyclone. Now, if I could put a pulley on in place of the front chain ring, that could work.

All that said, the idea I showed with three stages would only require me to make the mounts for Matt's drive. Going directly to the bb would require some more fabrication on my part. The plate to mount the motor and the mount for the plate to the frame on the motor end. And if I did a pulley in place of the front chain ring, I would have to machine that. I have a friend teaching me how to use a mill so I am not opposed to that, but I was trying to apply KISS.

I would recommend 12S 15ah minimum for your pack. 20ah would be best, though. That pack would handle the power and give good range while only weighing 13 or 14 pounds.

Awesome Matt, I was thinking I would do 12s 20ah using 8 of the 5ah 6 cell packs. Good to hear you recommend that. At least I know I am in the ball park there.

 

[MitchJi]

Hi,

What I had in mind is a belt 1st stage. Then instead of running a chain (2nd stage) to the BB run it directly to the right side of the Afine. In other words your second stage chain would be in the same as Gary's single (only) stage.

This would eliminate going through the BB which will be simpler (if you have room for a chain from the output of Matt's drive to the right side of the Alfine).

EDIT: To make that work you would need to mount the motor/drive on the swingarm which might be difficult and not the direction you want to go. For a Seat-tube mount your solution sounds like a good way to go.

 

[recumpence]

The primary reason I mentioned efficiency is because you are running multiple gears. Though your efficiency will go down with additional stages, the use of multi ratios means you can run the motor in its most efficent range for your given speed.

It is possible to get poor efficiency with RC systems, but if setup right, the effiency is mind boggling. One frisnd of mine only uses 800 watts to run his trike at 40mph. Amazing......... My recumbent bicycle requires 1300 watts to run 40mph.

Anyway, the best efficiency I see with my recumbent bicycle without any pedalling and coasting down all hills is 13wh per mile at 20mph. 15 wh per mile is not hard to see. However, wind resistance really builds up over 20mph.

Matt

 

[Miles]

Why not go directly from the first stage to the right rear of the Alfine? Something like Gary's build but with 2 stages instead of 1:

I don't think this would work, Mitch. The cable control input is right next to the sprocket, on the Alfine

 

[damcard]

Why not go directly from the first stage to the right rear of the Alfine? Something like Gary's build but with 2 stages instead of 1:

I don't think this would work, Mitch. The cable control input is right next to the sprocket, on the Alfine

When you say Mitch's idea wouldn't work, are you referring to there being two drive sprockets on the the right side of the Alfine and that the cable control would prevent that? If so, I am not concerned with the human powered sprocket and will not be doing that, but I will be driving the Alfine on the right side with the single sprocket.

My cyclone bottom bracket chain ring wobbles. I have seen that others have had problems with the bottom bracket chain ring wobbling too. Is this limited to the Cyclone cranks, or do all of them have that problem. I am trying to source the best crank/freewheel combination. I really want to get rid of the wobble. I am still not sure if it is my cheap cyclone bearing or the crank itself. The bottom bracket spindle is straight.

The Alfine gear ratios are 0.53, 0.64, 0.75, 0.85, 1, 1.22, 1.42 and 1.62

If I target 5th being 31 mph, that would put 1st at 16.43 mph and 8th at 50.22. I think that is about right. Currently I am leaning toward using the 8150 but that is a moving target for sure. I would rather be on the overkill side and just run the motor at a lower power level. Anyone see a problem with that? That will help me decide on the number of stages to use. Currently the three stage setup with Matt's single stage drive looks the easiest from a fabrication point of view. It also gives me a lot of flexibility.

 

[voicecoils]

When you say Mitch's idea wouldn't work, are you referring to there being two drive sprockets on the the right side of the Alfine and that the cable control would prevent that? If so, I am not concerned with the human powered sprocket and will not be doing that, but I will be driving the Alfine on the right side with the single sprocket.

I'd say so, there's no real room to shoehorn anything on the Alfine drive side (right side) and the cable exit guide gives little clearance.

A sprocket on the disk side (left side) is a possibility though, with a spline to 6 bolt IS adapter and then a sprocket or similar bolted to that.

I've had some gear slipping on my Alfine and it's only running on my pedal power. It may just need servicing, but here's hoping that you'll be able to run power through your Alfine without problems.

 

[damcard]

I've had some gear slipping on my Alfine and it's only running on my pedal power.

Ohh no! I looked around and heard they were really strong. You are the first to tell me that. When you say slipping, are the gears actually skipping or is it giving you a spongy feel? I have heard of a spongy feel on the outer ranges but not slipping. I will always be able to go back to a normal cassette if it does break.

 

[damcard]

If I cannot rely on the Alfine holding together, I will definitely go with the 3 stage reduction so I can roll back to the cassette hub.

At the risk of looking like an idiot, I started to figure up my ratios. Critiques are encouraged.

If I gear for 31 mph when the Alfine is at 1:1 I did the following:

31 miles per hour = .51666 miles per minute = 32 736 inches per minute = about 400 rpm at the rear wheel for a 26 inch wheel

12 series lipo = 44.4 volts * 197 rpm/volt = 8746.8 max motor rpm

1st stage: 8746.8 rpm / 5 = 1749.36 rpm (Matt's single stage belt drive) What is the best power/efficiency ratio for the belt drive??? I guessed 5:1 for now.
2nd stage: 1749.36 rpm / 4.25 = 411.61 rpm (16t/68t sprocket #25 chain) I have a lot of room to play here to adjust for a different ratio on Matt's drive.
3rd stage: 411.61 rpm /1 =411.61 rpm (22t/22t sprocket bike chain) This one is pretty much fixed at 1:1 if I can get a 22t granny gear on the crank.

Matt: is 5:1 the best ratio for power and efficiency for your belt drive? I can change easily if my numbers are right. I will have to verify the sprockets I listed here will adapt to my bottom bracket.

Thanks, -David

 

[Miles]

When you say Mitch's idea wouldn't work, are you referring to there being two drive sprockets on the the right side of the Alfine and that the cable control would prevent that?

Yes.

 

[MitchJi]

Hi,

Use one of these Calculators for your gears. I'd use MPH at 100 rpm for the Gear units pulldown.

Geared Hubs (Select the correct hub from the pulldown):
http://www.sheldonbrown.com/gears/internal.html

Use this for derailleurs:
http://www.sheldonbrown.com/gears/index.html

This is a better quality FW than the Cyclone although the FW and whatever crank you choose will probably have some runout:
http://sickbikeparts.com/catalog/product_info.php?cPath=21&products_id=62