Tongxin kit - 260rpm motor in 700c rim (rear/122mm)

frank9755

Esteemed Pedelecer
May 19, 2007
1,228
2
London
I'm selling my first Tongxin kit. It consists of:

Motor laced into a 700c wheel. Motor is 36v / 260rpm.
Controller
Twist throttle
Torque arm
5-speed freewheel (14-28 teeth)

Points to note:

Controller
Those who have read my posts will know that I've had some issues with controllers. The one with this is new / unused. It's from a mid-2009 batch that I bought from JohnP as a replacement but didn't need in the end (I think my controller problems arose because I had them mounted in an area where there was not enough airflow to keep them cool, so if you mount it somewhere like under the bottom bracket, it should fare better - the Cytronex guys and JohnP have used the same controllers without the failures that I had, so it was something I was doing!)

Motor speed
This is a high speed wheel which gives a top speed of 20+mph. The performance is similar to the Ezee Torq I, or the Cytronex with high speed wheel that AtoB got very enthusiastic about in their review. It is not a great hill-climber. It will help a stronger cyclist get up moderate hills quickly, but it won't help a weaker cyclist get up steep hills.

Rear motor
This is a rear motor with a screw thread. When I bought it I knew little about the complexities of fitting rear motors to bikes and thought I could put a 7-speed freewheel on it as a straight swap for the one already in my bike. As I now know, it is not as simple as that!

Hub width and freewheel
The width of the hub is about 122mm. With a 5-speed freewheel added it would be 135mm, which is the standard width for modern mountain bike / hybrid frames.
The Tongxin motor has a shorter axle length than others, such as the Suzhou Bafang, which are commonly made in rear wheel versions. The axle is only long enough for at most a 5-speed freewheel. For me this meant I would have to change my shifters, which I wasn't really up for at the time. So I gave up trying to use it as a rear wheel, and spread my front forks to use it as a front motor. I used pieces of wood to ease the forks apart gradually and sprung it the last few mm. As there was no easy way to get a replacement front motor, I used it like that and had no problems.

Here is a picture of the wheel (attached to a bike which is not for sale!) showing the forks spread to 122mm to accommodate it.

and there are a bunch more + the full story of the bike in this thread
http://www.pedelecs.co.uk/forum/electric-bicycles/1494-my-tongxin-kit-bike.html?

The motor has only done about 200 miles altogether and gave great performance along the main route I used it on - my commute from West to Central London. I still remember leaving the guys on Italian racing bikes for dead along the Embankment!

Altogether the parts cost me about £250 and I'd accept an offer of that amount or thereabouts. It wouldn't be the easiest thing to post as I don't have a suitable box, so would prefer if you could pick it up (London)

Frank
 

AndyOfTheSouth

Esteemed Pedelecer
May 15, 2009
347
4
Hi Frank

Looks good and is just right for somebody... perhaps next time a 190 (or 160?) in a 26" wheel? Then I really would be tempted!

All the best

Andy
 

daniel.weck

Esteemed Pedelecer
Aug 8, 2009
1,224
1
Interesting remarks about the over-gearing and the poor/average hill-climbing capabilities. I thought that the RPM was determined at manufacturing time by the windings density, not so much by the reduction gearing. I have a 260rpm Suzhou Bafang on my 16" Brompton which would make, I think, a fast full-size bike AND a good hill-climber too. But maybe things are different with the Tongxin friction gears.

I actually have a 80mm 180W 36V 190rpm Tongxin, ready to be laced into a 16" wheel. This will be my next project, to see if despite the low speed, hill-climbing assistance can justify the use of this Tongxin on my Brompton (the Bafang is big, heavy and noisy in comparison, but of course torquier, faster and more reliable under high load).

Anyway, good luck with the sale ! :)
Cheers, Dan
 

frank9755

Esteemed Pedelecer
May 19, 2007
1,228
2
London
Interesting remarks about the over-gearing and the poor/average hill-climbing capabilities. I thought that the RPM was determined at manufacturing time by the windings density, not so much by the reduction gearing. I have a 260rpm Suzhou Bafang on my 16" Brompton which would make, I think, a fast full-size bike AND a good hill-climber too. But maybe things are different with the Tongxin friction gears.

Cheers, Dan
Dan,
By overgearing I simply mean that it was deliberately put in a wheel bigger than it was designed for to get higher speed at the expense of torque and hill climbing ability - as you say the motor windings dictate the wheel speed.
Your 260rpm Bafang would give very similar performance to a 260rpm Tongxin. If you put it in a 700c wheel you would have something virtually identical to an Ezee Torq I - which were great bikes for some people, but a disaster for those who were in very hilly areas and/or not moderately strong cyclists. There are lots and lots of posts on subjects like Torq hill climbing, from about 18 months ago!
 

jerrysimon

Esteemed Pedelecer
Aug 27, 2009
3,277
108
Cambridge, UK
Hi Frank,

I am slightly confused is this a motor for the rear wheel it looks like its installed in the front wheel ?

The voltage and rpm is right for the Brompton I have ordered, but I am guessing even if its for a front wheel its not the 80mm Tongxin one.

EDIT

Ok I have just re-read the post and think I now understand :eek:

Whishfull thinking on my part that I might have actually found a Tongxin 80mm 36v/260rpm hub motor.

Sigh.......

Regards

Jerry
 
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