2-stage gear reduction hub motor on taobao!

[doctor_mono]

Hi, I have been searching taobao for parts to do a custom conversion with hub motors, I came across these 2, both from the same seller:

http://item.taobao.com/item.htm?id=15702738350
http://item.taobao.com/item.htm?id=15702686422

What is interesting about them is the gear reduction ratios. The first one (rear drive) claims 12:1 and the second one (front drive) claims 16:1. This makes me wonder if they are possibly built with 2-stage planetary gear reductions, at 3,4 and 4,4. Besides, a single stage reduction of 12:1 would be almost impossible. This would have been the first time I am aware of a hub motor with multi-stage planetary gears. Most geared hub motors I have seen use a single 5:1 reduction.

These motors have some high torque claims, which is good for what I am trying to build. But I am not sure about build quality/longevity/noise etc. Anybody here have experience with similar hub motors (high gear reduction ratio)?

 

[docnjoj]

You might want to check out Keyde.com for more infor on the 16:1 as it may be the roller moter. No gears and steel rollers. much cheaper too.
otherDoc

 

[doctor_mono]

otherDoc, aren't those the Tongxin motors using friction drive epicyclic gears or a clone? How is your experience with this type of motors?

I checked the web site and saw a recent (2012.07.29) "motortestreport" that tested up to 20Nm of load torque (at 16A) although the product page says 35Nm max, would love to believe the higher number but Tongxin's track record doesn't inspire confidence...

Their ebay price of $700 is kinda high. Both their taobao and ebay seller accounts show zero history so far.

 

[whatever]

I"ve checked over the website on taobao, one of the first motors that came out in china when ebikes were becoming popular was a two stage planetary
reduction system ( its not new ) and is still widely used in china, it was brushed motor, I notice on that site they sell a similar model ( brushed reduction they call it),
the seller is a reseller of various brands, rehashing each companies info, seems they sell bafang ( including bpm motor), they show a wide variety of motors, it would be simple to make up a site and just copy other companies info, if they are legit then they may just buy motors as needed if an order comes in.
Prices seem ok but guessing if they are just starting up their shipping rates will be high and they might try make a few more dollars on shipping as in common practice in china.
tongxin roller type motors are risky proposition, they have a history of problems, cracking of the large inner ring is common issue.

 

[docnjoj]

otherDoc, aren't those the Tongxin motors using friction drive epicyclic gears or a clone? How is your experience with this type of motors?

I checked the web site and saw a recent (2012.07.29) "motortestreport" that tested up to 20Nm of load torque (at 16A) although the product page says 35Nm max, would love to believe the higher number but Tongxin's track record doesn't inspire confidence...

Their ebay price of $700 is kinda high. Both their taobao and ebay seller accounts show zero history so far.

I'm afraid whatever is right about the older Tongxin roller motors. Jeremy Harris is building one with a folder bike so we should know about reliability soon. My old Tongxin failed after 4.5 miles, but that was about 8 years ago and they may be more reliable now. Amigafan is also going to try one soon.
otherDoc

 

[doctor_mono]

@whatever, i also noticed another item carried by this seller that looks similar to the 8fun BPM, bigger brushless geared black pie called XF39 and XF40. The performance characteristics must be close, except you can't custom order winding like you can for BPM/CST from greenbikekit or BMS.

Their prices on BPM and CST are quite similar to other reputable taobao sellers that also carry them (since June).

Just had short chat with the seller, and he indicated that he doesn't have any of the 2-stage geared motor in stock and he will have to order for me. When I asked him if he could custom order one that combines rear wheel drive setup with a 16:1 reduction ratio (which i only saw listed with front drive), he apparently asked the manufacturer and got back to me with a price in 20 minutes.

I am contemplating on buying motors and controllers via taobao shopping agents. Some of them claim they get 40% to 50% discount off the official shipping cost. We will see how that turns out.

For now I am looking at the 2-stage geared motor and a steel geared oil cooled motor (http://en.hengtai-cn.com/products/product-i331.html offered by many taobao sellers) as candidates. Both will be quite noisy though

 

[endlessly_ending]

Any news at 2-stage gear reduction hub motors ?
Myself looking for something in the 20:1 reduction range

 

[neptronix]

Interesting, but less powerful than a larger bafang or MAC/BMC. Not very light either.
I don't see the appeal. Unless you want a louder and higher pitched gear motor, hehe.