little Tongxin as crank drive - several solutions

K

Kraeuterbutter

100 W
Joined
Jun 14, 2007
Messages
197
Hi...

i know, here at endless-sphere the world starts with 30Amps/500Watt and more ;)
but maybe these is nevertheless for some of some interest:

in German pedelec-forum there are in the moment many trying to use hub-motor with the crank, for better hill-climbing..

Motor: the little, very light (2.1kg) and small Tongxin, rated with 180Watt
another benefit: it is internal geard something around 10:1
but instead of using normal planetary gears its using roller gears which results in a nearly noisless spinning of the motor

the motor is used best with a controller current limit set to 8-10A so it is not overstressed, and with 36V

the motor is geard by most users sofar with around 2:1 to the crank, so in the end - depending on the used tranny - the torque of the motor is in some cases more than doubled in the low gears of the bike compared to using it directly in the rim

here now some pictures from the German forum, for more details visit the german forum (and translate with google):
http://www.pedelec-forum.de

Bike from vauthech :
attachment.php

selfmade from carbon by him
as well as both bikes, completley build from carbon by his own
attachment.php

attachment.php

and more Pics:
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3466&d=1256034103
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3470&d=1256034395
this fully former weighted without electrics and with XTR around 9,2kg (!)
now with the electric setup (but no battery) and the 14gears speedhub from rohloff it weights also only 12.9kg (!)

second Bike:
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3483&d=1256115834
attachment.php

motor reduced in weight -> only 1.69kg !

weight of the bike including the whole drivetrain (but no battery): 10980g (!)
so with an light bottlebattery its around only 12kg !!

how to do it:
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3509&d=1256292564
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3517&d=1256379681


Bike from schwarzwaldächzer:
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3567&d=1256584379
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3568&d=1256584403
 
here some more bikes build with that configuration:

Bike from Nader:
attachment.php

battery in the bottle
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3297&d=1255265197
http://www.pedelecforum.de/forum/imgcache/1594.png
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3599&d=1256831371
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3598&d=1256831362

Bike from Grosserschnurz:
Cannondale Super V
attachment.php

attachment.php

bike is not yet finished
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3122&d=1253796673
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3075&d=1253709328
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3073&d=1253709217
http://www.pedelec-forum.de/forum/attachment.php?attachmentid=3085&d=1253722133
http://www.pedelecforum.de/forum/attachment.php?attachmentid=2982&d=1253207871

i know, the little 80mm Motor may only put out a maximum of about 200-250Watt...
nevertheless: 200-250Watt is about double as much as most untrained people can pedal by there own for longer time (most untrained people are around 80-100Watt)
AND: the 200Watt from the motors are always present, when going 35km/h straight or 10km/h up a hill..
so it will eventually even outperforme a in the wheel mounted hub-motor with 500Watt on a hill

so, maybe it was interesting for you..
we in the German Forum are already ordering 12 more tongxin motors with 80mm width, so soon there will be some more crankdriven bikes...
i have ordered one motor for myself too, and will try to laminate with carbon a motormount inspired by vauthech

the benefits of the little tongxin are as said:
* light weight
* waterproof
* internal gear, so low rpm (~160-180rpm under load)
* for the roller gears very quiet, for the low rpm very quiet (not comparalbe to fast rc-motors, which have lot of power, but are always noisy)
* cheap price
* freewheel of the motor
 
Dear Kraeuterbutter, Guten tag und willkommen!

I waited a day to allow others who are more experienced than me to comment first, but I can wait no more! The Tongxin motor is a good solution, and would benefit a large portion of the bicycle population.

The home-made carbon-fiber frame is a work of art. You have posted these motors are usually powered with 36V/10A, but could you tell us what is the maximum volts tried with them, and what were the results?
 
the results were posted here and in the english pedelec-forum:
the tongxin - when the torque gets to high - tends to "slip" the roller-gears

there were also reports of failed tongxins in 28"-bikes...
the motor is ideal in 20" bikes (dahon folding bikes, ....) when mounted directly in the wheels

so no, its not the ideal basis for overvolting and using 20A controllers and so on...
the motor is in that things a lot weaker than the Bafangs...
and even the bafangs here at endless-sphere-forum need to be beefed up with (loud metal gears) so that the motor survives the american style of pedelecs (i would say not pedelec but motorcylces to some of that monsters ;) )

so: its maybe the at least suitable motor on the market for overvolting and using higher currents...

but on the other hand its one (if not the) of the
* lightes,
* smallest,
* quietest
motor around

and because it can use the gears in the application shown above there are not 500Watt needed...
maybe you see also that the people use very tiny batteries (36V with 4Ah for example, mounted in a bottle)
thats enough for going 40-50km when using as pedelec...

so its the other direction: here in the forum many try to build "motorcycles" by using bycicles
with the tonqxin you stay realy with a bycicle (with low weight), keep the original bycicling-feeling and get nevertheless a lot of additional power (~200Watt, which is by human-power-means not that few)

i for myself are more fan of the "John Tez low power"-style
http://www.recumbents.com/wisil/tetz/E-AssistMetric/default.htm
so that my legs are still the primary power-source

for example: made a little tour last month with my Bafang-Motor (24V Version with 36V Battery), with 230km at one day, with trailer on my bike and only used about 600Wh of battery-energy (36V with 19Ah)
52kg weight (bike + trailer) and 8000feets of height to go over
 
Thanks for the links showing some very interesting designs. Does vauthech have a web site or build thread for the construction of his carbon fiber bicycle?

Bubba
 
yes, hopefully...

and: we made in the German forum a centralized buying/omnibus order: 20 Tongxin-motors
most of the buyers want to use it as a crank drive
so there will be some more builds too ;)

for building a carbon bike:

http://www.r-g.de/downloads.html

and here in detail: building a carbon-bike as pdf:
(its German, but lot of pics.. so maybe google-translate can help)

http://download.r-g.de/fahrradbau-aktuell.pdf
 
Hi Kb,

How much drag is there when the motor is freewheeling? That's the only thing that would bother me about this set-up - otherwise, it seems a neat solution.
 
yeah.. you have a good eye...
the tongxin is not that easy freewheeling like some other motors..

hmm... i hope its not to bad...
after 1000km the tongxin seems to freewheel half as light as on the beginning (at least: werner has tested it and posted it at his homepage)

he has compared some motors: you can see the results here on this Page:
http://www.wstiffel.homepage.t-online.de/Tongxin%20als%20Tretlagermotor.htm

i mean this section:
 
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