TONGXIN Datasheet/Dimensions/technical drawings ...

[kitchenman]

Could you not use the spoke holes to mount the actual motor and then use the axel to rotate a sprocket instead of the other way round?

Might be a daft idea as the spoke holes might not create good mounting brackets. Just an idea though.

Umm .. dont think that'll work .... the electrics will wizz around at amazing speed .... (a bit like my head!) ..

 

[Scottyf]

Oh right does the wiring not come through the Axel then?

If not D8veh looks like the simplest soloution to creating the drive you require.

But using the spoke holes to fasten an outer ring to sounds interesting. If only you could burtcher up a large chain wheel sprocket to do the job.

 

[flecc]

The method d8veh recommends works well. I use a similar approach with a cut off alloy hub to add a freewheel thread to a front SB motor, converting it to rear use:

 

[Deleted member 4366]

. can you just clarify how you have connected to the hub? .. Did you use the 6 holes that are in the hub? Its my understanding that these 6 holes are not the same as the 6 holes you would have in the disk version of the Tongxin ... or have I got this wrong? ...

The BMX hub didn't have any holes in it for the diskc because it's the drive side. The Bafang motor comes with a a little plastic spacer that you remove when you fit a disc. This spacer makes a nice template to mark the hole positions in the adaptor, otherwise you could just use a disc as a template. The motor mounting bracket is just a top-hat shape with a hole the shape of the axle filed in the middle. It just fits up the centre of the free-wheel with enough room to get a socket on the nut. You don't really need a freewheel, you could just use a fixed wheel sprocket, but the freewheel ones are easier to get, especially as they are normally already on the BMX wheel/hub. The end result is that you get two freewheels: The one in the hub and the one in the sprocket. Whichever one gives the least drag will be the one freewheeling. If you don't like the noise from it, fill it with Araldite and use the motor one.

 

[kitchenman]

Oh right does the wiring not come through the Axel then?

If not D8veh looks like the simplest soloution to creating the drive you require.

But using the spoke holes to fasten an outer ring to sounds interesting. If only you could burtcher up a large chain wheel sprocket to do the job.

I also thought to using a belt drive system. I was thinking that it may be possible to wrap the hub with a belt cog band .... if such a thing existed! .... I haven't got as far as thinking how the belt cog band could be fastened. But lets say it could be stuck. How good would that be? ... It would mean no messing with the hub or the spoke holes .... just stick on the magic band and away you go! .... for me, and my application, I would then need a regular hub to connect to the rear hub and front cog.

 

[kitchenman]

The method d8veh recommends works well. I use a similar approach with a cut off alloy hub to add a freewheel thread to a front SB motor, converting it to rear use:

View attachment 2645

I was hoping to avoid screwing into the hub but if I have to then so be it! ... COuld I use this hub do you think?

 

[flecc]

You should be able to use that cassette hub in a similar manner, but I'm not familiar with the Tongxin details, perhaps others can advise on that suitability.

 

[kitchenman]

You should be able to use that cassette hub in a similar manner, but I'm not familiar with the Tongxin details, perhaps others can advise on that suitability.

Thanks. Is this a hacksaw job or do you have special cutting machinery?

 

[flecc]

I hacksawed my hub in half first, but used a lathe to machine of the rest of the centre, back to the hub spoke flange.

 

[kitchenman]

I hacksawed my hub in half first, but used a lathe to machine of the rest of the centre, back to the hub spoke flange.

Thanks Flecc. Regarding the cogs do you think I need bolt on cogs, freewheel cogs or both? ... Can you help me with my thinking? ... As the hub is basically a freewheel I'm thinking I can use bolt on cogs. One connected to the rear cog on my Rohloff and one connected to my crank. Do you see any issues with this config? ...

 

[flecc]

If I understand you correctly, bolt on cogs at both ends will mean you couldn't have the motor driving with pedals stationary, but that may not be an issue for you, especially if using with a pedelec sensor. Otherwise, using the motor freewheel only is fine, seeing as the Tongxin is so free running.

 

[kitchenman]

If I understand you correctly, bolt on cogs at both ends will mean you couldn't have the motor driving with pedals stationary, but that may not be an issue for you, especially if using with a pedelec sensor. Otherwise, using the motor freewheel only is fine, seeing as the Tongxin is so free running.

Yes. Bolt on cogs means no motor when pedals stationary. If I use the freewheel AND don't use a pedal sensor then I could have motor without pedalling.

 

[kitchenman]

Ok .. got what I need now ... I think! ....
Here are the measurements:
View attachment 2613

So... My plan is to screw 2 chain rings using the exisiting holes. One with 18 teeth to connect to the front crank and one with 24 teeth to connect to the 15 teeth connected to my Rohloff ...
if anyone can spot any holes in my plan (sorry!) ... then please shout!

Umm . Actually these are not the dimensions of my Tongxin hub! It may be a Tongxin but it ain't mine! ..

 

[Scottyf]

LepusMotorGeräusch - YouTube

Get one of those rigged up!

 

[kitchenman]

Get one of those rigged up!

Now thats what I'm talking about! ... added to favorites. Bracket system is excellent and has room for adjustment which I've been thinking about. I suppose he made it? ... Been looking for "tube clamps" etc ... in the hope of being able to cobble something together ...
Thanks ...

 

[Scottyf]

Looks home-made but looks like it does the job well.
Least that way you can keep the free wheel ability etc.

Although getting the brackets made and fitted would be the difficult thing but by no means impossible.

Hey it sorted Alan!

I can always speak to some of my friends in engineering that could whip some brackets up!

 

[kitchenman]

Looks home-made but looks like it does the job well.
Least that way you can keep the free wheel ability etc.

Although getting the brackets made and fitted would be the difficult thing but by no means impossible.

Hey it sorted Alan!

I can always speak to some of my friends in engineering that could whip some brackets up!

Thanks Scot, I'm not going to turn that offer down! ...Please do! .. Even if they don't actually make anything I'd like to know what they think. An all singing and dancing clamp would allow for different size tubes and be adjustable vertically and horizontally! ... thats all I want!

 

[kitchenman]

The motor mounting bracket is just a top-hat shape with a hole the shape of the axle filed in the middle. It just fits up the centre of the free-wheel with enough room to get a socket on the nut.

d8veh, do you have a pair of these that you would be willing to part with? ... How many mm do they take up on the axle? .. 2mm?

 

[kitchenman]

Ok .. here we go with version 1 which I call the HAC (hub adapter clamp) - 2 brake rotors and some nuts and bolts clamping around the Tongxin ...

Hub adapter clamp - a set on Flickr

 

[kitchenman]

Ok .. here we go with version 1 which I call the HAC (hub adapter clamp) - 2 brake rotors and some nuts and bolts clamping around the Tongxin ...

If the clamping could survive the 175 rpms and I didn't mind the extra weight then it may be worth testing ... however, I don't think it will and adding 500g is a bit silly! ... I suspect my actual solution will morph out of this and bring into play the spoke holes as fixing points... however, just happened to pick up a broken seat post clamp in the shed and it fits like a glove! ...

but, again, is a clamp going to withstand the force being applied to it? ....