Tongsheng questions

Electrically assisted bikes, trikes, etc. that are legal in the UK
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javatime
Posts: 184
Joined: 27 Jan 2007, 11:08am

Tongsheng questions

Post by javatime »

I have just finished my first E bike using a Tongsheng mid unit. It all goes well but a few questions here :

I am running 29er wheels on an MTB (2.4 in tyres). I am about to set the wheel size in the display. The default is 26 ins but this must include a nominal tyre ? I need to change mine to something more than 27 ins (700c) to get the correct circumference for the big tyres.

Any suggestions ? and does this have any other effect other than showing the correct speed / distance on the display. Does the controller use this information at all for the power assist etc

Also the supplied drive side crank throws my right knee a long way out. Any suggests for a drive side crank with a smaller "q" factor.

Finally, are there any issues with fitting a MTB chain ring (34T) I can get around mechanical installation problems / chainline - more interested in the effect this might have on electric motor performance / assist.

Many thanks
rotavator
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Location: North Wales

Re: Tongsheng questions

Post by rotavator »

For the driven wheel's actual diameter, I would simply measure it with a tape measure, including the tyre obviously.
stodd
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Joined: 6 Jun 2018, 10:24am

Re: Tongsheng questions

Post by stodd »

javatime wrote: 25 Jan 2023, 5:42pm Any suggestions ? and does this have any other effect other than showing the correct speed / distance on the display. Does the controller use this information at all for the power assist etc
The controller must use it for speed cutoff; it doesn't have any other inputs it could use.
rjb
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Location: Somerset (originally 60/70's Plymouth)

Re: Tongsheng questions

Post by rjb »

34 tooth chainrings are one of the choices offered with the Tongsheng unit. The rings are offset inwards to improve chainline. My Tongsheng unit was installed as close to the chainstay as I could get it to minimise any chainline issues. :wink:

If the RH crank is too far out you could try any right hand crank to hand but you may have an unused spider which may look cosmetically odd. Not sure anyone makes a right crank without a spider and chainring. Possibly only e bike motor units.

My controller (vlcd6) only displays distance in km so I have a bike computer on the bars showing miles.
I fitted my kit to a 26" wheel tandem with the settings as delivered straight out of the box. Think the default setting is a 25" wheel. Can't say I noticed any issue.
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
hemo
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Re: Tongsheng questions

Post by hemo »

My Ute has a tsdz with a 32 /42t double, 32t is the smallest feasible. With a longer chain stay , chain line is never an issue.

For Q factor I installed a pair of E6000 crank arms but also had to shave some 5mm off the inner boss for a tighter fit.
Other cranks, users use are Bafang BBS cranks or nicer Yamaha /FSA CK220 JIS cranks.

For wheel size my 650b are input in mm via the OSF software tools , though one can also I believe do so by button pushing on the display. The vlcd5 I use is I find not very user freindly for settings as ther are too many button presses to carry out, as I have OSF I find this the much easier route to make any changes.

Wheel size input is 14" - 32" according to the vlcd5 manual.
tenbikes
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Joined: 11 Jan 2009, 6:41pm

Re: Tongsheng questions

Post by tenbikes »

Leki make cranks specifically to address the problem of off set on Bafang mid drive motors. I don't know if the figures involved are close enough for them to work with other makes.

They are very well made. I used the 160mms version which works really well for me. Cost two years ago something like ?120£? if memory serves.
javatime
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Joined: 27 Jan 2007, 11:08am

Re: Tongsheng questions

Post by javatime »

Many thanks everyone for the help - especially on the cranks !
javatime
Posts: 184
Joined: 27 Jan 2007, 11:08am

Re: Tongsheng questions

Post by javatime »

rotavator wrote: 25 Jan 2023, 5:59pm For the driven wheel's actual diameter, I would simply measure it with a tape measure, including the tyre obviously.
Many thanks - I always thought 26 inches, for example, was the rim diameter - it actually seems to include a "nominal" tyre if I understand Sheldon Brown correctly !
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velorog
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Location: East Yorkshire

Re: Tongsheng questions

Post by velorog »

I have fitted Bafang cranks to my Tongsheng set-up. They reduce the Q factor by about 10 mm at each side and at £20 a pair offer a cost effective solution.
tenbikes
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Re: Tongsheng questions

Post by tenbikes »

velorog wrote: 27 Jan 2023, 10:01am I have fitted Bafang cranks to my Tongsheng set-up. They reduce the Q factor by about 10 mm at each side and at £20 a pair offer a cost effective solution.
That's good to know. Do they balance ok? Before fitting the Lekis my cranks were offset about 15mm.....
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velorog
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Location: East Yorkshire

Re: Tongsheng questions

Post by velorog »

The design of the Tongsheng is that the RH crank is offset by 20mm. Fitting Bafang cranks does not eliminate the off-set but reduces the Q factor by 20 mm..The Bafang cranks are symmetrical whereas I presume the Leki cranks must be asymmetrical if they reduce the off-set. The off-set has never been a problem for me when riding but I did feel uncomfortable with the original Tongsheng cranks and their massive Q factor.
tenbikes
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Re: Tongsheng questions

Post by tenbikes »

Thanks for that, useful information.

I'm the opposite. I ride fat bikes with huge Q factors and really like it. Much better for my old hips;)
But I felt the off set would really throw things out. Maybe it would have been ok, but I only did a few miles before switching cranks.
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