Single stage reduction project, input wanted

[Kaz]

Once again spring is getting near. And that of course means that money starts to burn a hole in my pocket and I can feel the ebike fever rising. About time to do something about it...

My current plan is to make a single stage reduction unit, sandwiched between aluminium plates, with LH drive chain to the rear wheel. Max speed of 40kph and budget of <550$ is my aim.

Here is the parts list I've been thinking.

Hobbyking.com
2x 83.64$ Turnigy 5000mAh 6S 20C Lipo http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9176
1x 17.99$ Hobbyking 6S 50W 5A Charger/Balancer http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=11668
1x 36.59$ Tz85A Turnigy Brushless ESC 85A w/ 5A SBEC http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10331
1x 4.99$ Programming card for Tz85A http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10459
1x 5.99$ Turnigy Servo tester http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=8296
1x 23.95$ Turnigy Watt Meter http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10080
46.67$ EMS Express 3-4 Day Shipping to Finland
----------
219.82$

Ebay.com
1x 65.45$ Aeolian C6374 170kv motor http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180609554846
1x 34.99$ Meanwell 12VDC 12A Power Supply http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370480864002

LiveFastMotors.com
1x ~35$ 48t Rear wheel sprocket kit http://livefastmotors.com/Gas-Powered-Engine-for-Bicycle-48-Tooth-Rear-Sprocket.html

Another motor option: Turnigy SK 63-74 http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7870

Other parts I still need:
Sprockets for the motor and middle shafts. Calculating from the desired top speed and already chosen parts, the first reduction step should be about 1:3.5. 11t motor sprocket and 38t axle sprocket should be about right.
Adapter for the freewheel. I probably have to get someone to make this one for me. Hopefully it doesn't get too expensive.
Hall thumb throttle. Most likely from ebay.
Automotive fuse and a holder. 80A one to protect the ESC.


I haven't messed around with RC-stuff before, so I've got lots of questions still unanswered in my head, but here's some I'd like input on:
1. Apparently all chain drive can be noisy, that's why people are using belts. Does it make any difference if the motor sprocket would be 14t instead of 11t?
2. I know that the cheap ESC is not the best available, but is it enough if I plan only to pull about 1200W from this drive? That should still leave some room for spiking.
3. Any general comments about the selected parts? Please point things out even if they seem like no brainers.

Thanks in advance for all the replies!


Edit: Added the second motor option and removed the freewheel with wrong threads.

 

[www.recumbents.com]

I think that the servo tester requires a 5K resistive throttle rather than the hall sensor variety.
If you are using the BMX freewheel as a drive cog, then it's a standard freewheel/threads, not flipflop.
5Ah is not going to get you very far...

 

[gwhy!]

Hi kaz,
I think a sensorless esc is a none starter unless you go down the CC route for a bike geared for 40mph. Also I would go with a motor from HK ( as you have a shopping list from them already ) http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7870 and look into fitting hall sensors to the motor and then you can use a lynen sensored modded controller ( member on this forum ).

 

[Kaz]

Good point about the throttle and thanks for clearing the freewheel issue. I got confused about the BMX terms. :? I know two lipos are not much, but I figured that it should be enough to get me started and on the road. I can always order a few more later.

Gwhy, 40 km/h, not 40mph. I also know that it's easy to fry the controller if I try to accelerate from complete standstill and I should get some speed before touching the throttle. But does any of that make any difference in this case?

(Adding sensors to the motor is already on my long list of future things to come.)

 

[gwhy!]

Gwhy, 40 km/h, not 40mph. I also know that it's easy to fry the controller if I try to accelerate from complete standstill and I should get some speed before touching the throttle. But does any of that make any difference in this case?

(Adding sensors to the motor is already on my long list of future things to come.)

25mph :lol: would be a much better top speed for a cheaper esc ( and possible ) My first venture into a rc setup I used a 100A rc controller with the motor I pointed to, it worked but did have sync issues when trying to pull away from a standstill but if I peddled a little to get a bit of speed before touching the throttle it was fine ( but always felt it could pop at any moment ) I fitted a much larger heatsink onto the controller which helped a lot but still didnt feel 100% confident that it would last hence one of the reasons going to a sensored controller. So if you go down the cheaper rc esc route then get at least a 100A one.

 

[Kaz]

How about this Turnigy K-Force 100A ESC? http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9328 That heatsink looks like it can be easily upgraded to a bigger one. ~20$ more than the previous cheaper one, but I also save a few bucks if I buy the motor from them instead of ebay.

 

[gwhy!]

How about this Turnigy K-Force 100A ESC? http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9328 That heatsink looks like it can be easily upgraded to a bigger one. ~20$ more than the previous cheaper one, but I also save a few bucks if I buy the motor from them instead of ebay.

I have had no experience with that controller, the one I was playing with was this one http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=4691

the one you pointed to looks like it may do the job but it is only a 6 cell esc so will not be any good for voltages above 22.2v but like you say it looks easy enough to replace the heat sink with a larger one. I was running mine on 44.4v..

 

[Kaz]

I've decided to go with the K-Force ESC and see how it holds up. I'll probably order the parts from Hobbyking tomorrow and once I receive them, I can properly start making the reduction unit.

 

[MitchJi]

Hi,

1. Apparently all chain drive can be noisy, that's why people are using belts. Does it make any difference if the motor sprocket would be 14t instead of 11t?

An 11t primary drive sprocket will definitely be noisy.

This is what Gary said about his experience with an 11t drive sprocket (I highly doubt 12t would be much better):

WIn the brief time I used it, I had no problems at all, but this 3220 "direct drive" setup just makes way too much racket, for my tastes...

...I hate the direct drive setup I have now because it just makes such a horrible racket...

...The problem with trying to do a direct drive ratio of 8 or 9:1 is that the drive sprocket needs to be small and that means it will make a lot more racket...

...At some point I'm going to change my 11t motor sprocket to a 12t, which will bump the top speed in 1st to about 20 mph. This should also reduce the horrible racket my setup makes. That is the biggest problem with not having the belt drive 1st stage, it makes a horrible amount of noise, which is made worse by the small 11t sprocket...

...with the "direct drive" setup I did with the 3220 and the large #35 sprocket. That too sounded like somebody dumped a bucket of bolts into the spin cycle of a washing machine...

... due to the chordal effect. It is hard for a chain to get around a sprocket that has fewer than 11 or 12 teeth. It ends up sounding like bucket of bolts in a washing machine...

14t should be large enough to be reasonably quiet. If you use chain for the primary reduction I'd use #25 chain.

Adapter for the freewheel. I probably have to get someone to make this one for me. Hopefully it doesn't get too expensive.

Matt, Sickbikes and Staton all make FW adaptors (various shaft sizes).

 

[Kaz]

Thanks for confirming the chain noise issue. I've been looking at SPD/SI's online store it looks like it might not brake my budget badly if I change to belt drive. 24 to 72 seems to be the biggest ratio they have pulleys with suitable bore size. Now I'm just wondering if 9mm wide belt is enough for <2kW setup, or should I pick 15mm wide instead.

Also thanks for pointing me to Staton Inc. Found a good looking freewheel + adapter combo from them. Currently waiting a reply from them about shipping costs.

 

[McDesign]

Engineering rule of thumb is that 17t is minimum for quietness; 23t is a better minimum.

Forrest

 

[MitchJi]

Hi,

Engineering rule of thumb is that 17t is minimum for quietness; 23t is a better minimum.

With #25 (which he said is a little quieter than #219) for a primary sprocket Matt said the noise isn't bad. D's seemed OK with an 11t secondary (using about a 3:1 primary belt).

I've been looking at SPD/SI's online store it looks like it might not brake my budget badly if I change to belt drive. 24 to 72 seems to be the biggest ratio they have pulleys with suitable bore size.

I'm not sure about their prices but pfeifer industries has a much larger selection: http://www.pfeiferindustries.com/index.html

Now I'm just wondering if 9mm wide belt is enough for <2kW setup, or should I pick 15mm wide instead.

Matt (recumpence) also stocks some pulleys and can advise you on width (send him a pm):
http://endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=6262

For under 2k at 15mm I'm sure 20t/80t would be fine.

 

[SoSauty]

Hey Kaz, look into the stickies at the 1st of "E-bike Non-hub Motor Drives." Scroll down and bit and there's a PDF link to technical info on synchronous belt drives. Using a slipper clutch will allow a slightly narrower belt.