My wife's new Tongxin bike

frank9755

Esteemed Pedelecer
May 19, 2007
1,228
2
London
I said I'd post some pictures of the new Tongxin bike that I've built up for my wife. Now that it is working well, I'll risk doing so.








The bike is a new Viking step-through frame. It is a fairly low spec bike, but one of only a couple of models I managed to find for sale in the UK which met her criteria, which were:
step-through frame
700c wheels
non-suspension forks
broad range of gears including triple chainring (this ruled out the Dutch bikes)
rack and mudguards
chainguard (this one ruled out hundreds of bikes!)
Revoshift preferred
Not too heavy

I upgraded / changed / added a few bits, notably:
gearing - changed from a 6 to a 7 speed megarange
shifters (6 for 7 speed)
rear mechanism - took off the basic shimano and fitted a Deore LX that I had in the garage, for an extremely smooth shift
stem and handlebars - fitted a high rise stem with swept back bars that my wife bought in the Netherlands
Abus wheel lock fitted

I fitted the Tongxin kit with my preferred set-up of thumb throttle with no spring. It currently has an eCrazyman controller, which is quite a bit bigger than Tongxin's own one, so is more noticeable. Keywin (aka eCrazyman) assured me that this one had higher spec mosfets and should not burn out, although it seems to give about 10% more speed than the Tongxin one did.

The motor is a 260rpm but I also have a 175 for hillier country. The IEC connector means it is a two minute job to swap the motor wheel over. The 260 is for high speed. It will give assistance up to c.25 mph (but beware of controller burn-out if used at full throttle for extended periods!) but is not much good on steep hills. The 175 is the same as fitted to the Cytronex so is a decent hill climber and can assist up to about 17mph on the flat.

The battery is a Ping LiFePO4 - 36v/10Ah.

Finally, my new battery storage system - a Carradice saddlebag. Hardly a new product but I've not seen anyone use it for a battery before. Better balance than a pannier and better looking than a rack or frame pack. It doesn't move around when in use and the rack supports it well. We've not done it yet, but we could squeeze two batteries in there for up to 60 miles range.

Bike weight with one 10Ah battery is c.22kg
 
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Barnowl

Esteemed Pedelecer
Sep 18, 2008
954
1
Very impressive looking conversion. Mrs B would love that.. The saddlebag does a great job of disguising the battery. I'm considering converting my wifes ladies Raleigh alpha sport (the one with the double top tube) with a Tongxin. The saddlebag approach would be a nice retro touch.
PS. Good luck with the controller.
 

eddieo

Banned
Jul 7, 2008
5,070
6
A very nice job!

hardly looks electric......the motor is very unobtrusive
 
C

Cyclezee

Guest
Well done Frank. Another really nice creation and you would have to look closely to see it is electric;)

J:) hn
 

flecc

Member
Oct 25, 2006
53,152
30,567
Very nice Frank, shows what can be done with a good choice of base bike and the Tongxin motor. There's many a manufacturer who would be happy to have this in their range with an unobtrusive custom battery mounting.
.
 

Vikki

Esteemed Pedelecer
Jan 12, 2009
442
2
That's really smart, well done on an excellent job.

Vikki.
 

musicbooks

Esteemed Pedelecer
Oct 10, 2007
719
29
Super Frank,
My wife had a shimmy and loved it. You'd never know it was electric.
You've got yourself the makings of a nice little business there.
bw
musicbooks
 

andyh2

Esteemed Pedelecer
Jan 8, 2008
297
1
Jolly good Frank. Makes me wonder if I should put one together for my not ridden a bike in 3 years wife.
 

frank9755

Esteemed Pedelecer
May 19, 2007
1,228
2
London
Thanks everyone for the comments!

It's a 36v motor, standard (100mm) width. That one is a 260rpm but it normally has the 175rpm for everyday use (although they look the same!).
 

AndyOfTheSouth

Esteemed Pedelecer
May 15, 2009
347
4
Would it be possible in principle to put the 175 rpm one in the back wheel and switch between that and the 260 rpm in the front, according to whether speed or hill-climbing were required?

Just a thought... :)
 

frank9755

Esteemed Pedelecer
May 19, 2007
1,228
2
London
A thought I've had too, Andy, and I do have a 260rpm rear wheel hanging up in my garage!

But I've not done it yet because I think it would end up being too heavy and moped-like, and I don't think that plays to the strengths of the Tongxin. It would be heavy because it would need two controllers and two batteries. It would need two sets of controls making it more complicated to use - whatever combination of throttle, pedelec, brake cut-offs, switches was deemed best (eg the 175 being pedelec only / always on with the throttle powering the 260, would be one feasible combination). Also, it would also be illegal and, for some more importantly, would look as if it were illegal.

A further complication is that the Tongxin rear wheel only has a long enough axle to take a 5-speed freewheel, and to make the most of a 260rpm motor, you do need a high gear (ideally >>100"). That's not the end of the world though, as 14-28 5-speeds can still be found, and with a triple chainring up front, a reasonable gearing range is still possible.
 

AndyOfTheSouth

Esteemed Pedelecer
May 15, 2009
347
4
A few points - I was assuming one battery.

Couldn't the legality aspect be satisfied by an 'either or' switch? (Of course, it couldn't be overridden if there was a particularly steep hill. That would be cheating, wouldn't it?)

Similarly, couldn't the wiring be simplified by having one throttle controlling both motors and not having cut-out brake levers?