Robbin your right the second image does look more like the spline on the Tongxin.

 

It also has a simlar spacer as shown here

 

Regards

 

Jerry

Edited December 20, 200916 yr by jerrysimon

Not easy to find but there is a roller brake to disc brake adapter available:

Cesur disc adapter

 

I don't know if it has been tried on the Tongxin hub.

 

Robin

Edited December 20, 200916 yr by RobinC

The splines look to be too big for a centrelock disc mount, so I think it is intended for a roller brake. The larger slots in the pictures of the Shimano disc above are on the lock ring which holds the disc onto the hub. It uses the same tool as used for cassette lockrings.

Shimano XT disc hub

Nexus hub with roller brake mount

 

Robin

 

Thanks Robin, interesting. That's a first for Tongxin, using a roller brake on a hub motor, the other hub motor

companies all using the band brake or disc brake on these. I don't like the idea though, given how weak roller

brakes generally are.

.

Jerry, any chance of a link to where you bought the motor & controller from? The tongxin site doesn't appear to handle internet sales.

 

http://www.tongxin.net.cn/en/product.htm

 

Chris.

Edited December 21, 200916 yr by 1967geezer

Thanks Robin, interesting. That's a first for Tongxin, using a roller brake on a hub motor, the other hub motor

companies all using the band brake or disc brake on these. I don't like the idea though, given how weak roller

brakes generally are.

.

 

The smaller roller brakes were very under-whelming, the IM70 is OK-ish and the new IM80 might be a decent brake.

Look at IM80 vs IM70 halfway down page

 

Robin

where are you people getting those digital calipers from? Saw a set on Screwfix but they don't look as good..

 

Maplin do them for £20, but keep an eye out as they are often on special for a tenner.

 

100mm Digital Vernier Calliper : Enviroment Testers : Maplin

Maplin do them for £20, but keep an eye out as they are often on special for a tenner

 

Those are only 100mm/4" ones. I think 6" or 8" ones are far better for general purpose use.

 

PS I have been PMing people details of the supplier/contact I have.

 

Regards

 

Jerry

Edited December 21, 200916 yr by jerrysimon

Ok had a little time after the Boxing day walks to intially lace up my wheel.

 

I am pretty sure its NOT quite right. The pattern is right but my inside spokes are leading not trailing when the wheel it rotated in the correct direction for the bike to move forward. I need some of you expert wheel builders to comment

 

This picture was taken near the end of the process where I found it necessary to place the wheel on my lap and push down on the hub to get the last few spokes in.

 

http://farm3.static.flickr.com/2714/4215401209_fa37ffe29e_o.jpg

 

Ok here is a picture of the wheel from the side. In this picture the wheel will roll clockwise towards the right for forward movement. Note how the trailing spokes are then on the outside of the flange rather than the inside for this movement. I think technically this is wrong. Interestingly my Cytronex wheel appears to be the same though on that, the spokes go over one spoke and under a second spoke before entering the rim. On this smaller wheel the spokes on the outside of the hub just go over those on the inside of the hub as there is not enough flex/room for them to go under.

 

http://farm3.static.flickr.com/2530/4216172318_00f996ed2e_o.jpg

 

So in summary if you turned the wheel anti clockwise i.e the bike was moving backwards, the spokes would be correct i.e. inner hub spokes would be trailing and outer hub spokes would lead. Ok final picture looking down.

 

http://farm3.static.flickr.com/2568/4216172176_280e6307da_o.jpg

 

Its all loose at the moment so easily taken apart again. The spokes on the outside of the hub do bend out a little and are not touching the spokes on the inner side of the hub where they cross. I assume as I tense up the wheel they will touch/rub ?

 

I have each set of spokes going into the correct offset rim holes left and right. Interestingly at this stage all the spokes on the inside of the hub are rattley loose whereas the spokes on the outside of the hub have some tension in them as they had to be bent over slightly to get them into the rim holes. Is this correct ?

 

Regards

 

Jerry

 

spokes are

Edited December 26, 200916 yr by jerrysimon

Here is the Cyrtonex wheel which is identical to my build above except as I said the spokes are laced over under on each side of the hub flange.

 

http://farm3.static.flickr.com/2706/4169460543_45ee4f147a_b.jpg

 

Regards

 

Jerry

Edited December 26, 200916 yr by jerrysimon

Jerry

 

I don't qualify as an "expert" wheel builder, but have enjoyed building 700C large diameter wheels for the Bafang motor on the Torq, and more recently for the hub geared wheels on the back of the Kalkhoffs. I am a big fan of Roger Musson's techniques, and the wheels have given no trouble !

 

Correctly, you have used a "1 cross" lacing pattern because of the large diameter hub and the small diameter rim (mine have all been large diameter rims like your Cytronex, using a "2 cross" pattern).

 

With the wide spacing of the hub flanges, personally, I would prefer that the "trailing" (or "pulling") spokes arrive at the inside face of the flanges, giving a straighter pull.

 

This is not a hard and fast rule, and you will find wheel builders are divided on the subject.

 

As you begin to even up the tension on the spokes, it is most important to work on the stress relieving of the spokes. Wear leather gloves and "squeeze" pairs of spokes together, such that the 90deg elbows are moving towards 95deg for those on the outside of the flange, and 85deg for those on the inside of the flange.

 

This aims to make a straight spoke from flange to rim, rather than an arced spoke which is flexing continuously at the elbow.

 

As you apply more tension to the spokes, you might interrupt the work 4 or 5 times to stress relieve the spokes. Some consider this the most important step.

 

James

Thanks James,

 

I haven't got to the "squeeze" stress relieving bit yet. I paid for and downloaded Roger Musson's techniques book and followed it to the letter. The mistake I think was that I assumed that his use of the term "freewheel" meant the gear side of the wheel (right side)which is probably why now my trailing spokes are on the outside of the hub flange. Also his example build is based on a rear wheel not a front wheel.

 

If I had followed the Sheldon Brown's web site page on wheel building I would have got it the right way round. Sadly I see Sheldon died recently but what a great web site and wealth of knowledge he has left for us all.

 

For my own peace of mind I think I will re-lace it the other way round with the trailing spokes on the inside of the hub flange as you say.

 

Regards

 

Jerry

Edited December 26, 200916 yr by jerrysimon

Hi Jerry !

I agree about trying to make the spokes as straight and non-twisty as possible before putting tension into them. This stress-relieving procedure was not very intuitive when I did it, I didn't manage to get a "feel" of the wheel so I just followed instructions hoping I was doing the right thing. So far my wheel tension is holding well and the rim is still true vertically and laterally. Obviously, failures may happen any time as my mileage increases...we shall see

 

Regarding the leading versus trailing spokes: you might as well start all over again just like you said. This way you will feel more confident about your bike when you ride it, and you will have no regrets The second time is bound to be easier, right ?

Ok thanks for all the replies. Thirty minutes later and I have it relaced. Second time round it was much easier the trick is to only do a few turns on the nipples when you first insert the spokes.

 

Here we go. Viewed from the side (clockwise = forward motion of the wheel) the trailing spokes now go out from the inside of the hub flange

 

http://farm5.static.flickr.com/4020/4216164581_4423bb011e_o.jpg

 

And viewed from the top

 

http://farm3.static.flickr.com/2737/4216934032_86c17a22b5_o.jpg

 

The leading spokes definately have a little more tension in them at this stage than the trailing spokes which rattle. Is this where even at this stage I should squeeze the pairs to try and get them equally tensioned before I start tightening things up ?

 

Any more other comments, I am pretty sure this is now right.

 

Hopefully tomorrow I can start tensioning it all up and truing it and maybe actually get it built and go out for my first test ride

 

Regards

 

Jerry

Edited December 26, 200916 yr by jerrysimon

With the wide spacing of the hub flanges, personally, I would prefer that the "trailing" (or "pulling") spokes arrive at the inside face of the flanges, giving a straighter pull.

 

This is not a hard and fast rule, and you will find wheel builders are divided on the subject.

 

James I just read your reply again and saw the link you posted to one of your earlier posts. The link was perfect and illustrated my delema here perfectly. Its also finally helped clarify things for me so many thanks. What a great forum this is!

 

Interestingly you mention Roger's book which I also purchased a while back.

 

Having re-read the book I realise now that there are actually 4 different ways you can set the spokes in the hub flange.

 

1. Trailing (pulling) spokes on the inside of the hub flange

2. Training spokes on the outside of the hub flange

3. On the drive side trailing spokes on the inside of the hub flange and then on the outside for the non drive side

4. On the drive side trailing spokes on outside and inside on non drive side.

 

1 and 2 are mirror images and 3 and 4 are opposites. Some use 3 or 4 where disk brakes are fitted etc.

 

He states that he in fact uses technique 1. on all his wheel builds. I now undertsand what is going on and as they say there is no substitute for practically building a wheel to see and undertsand this stuff. I think in summary there is in fact no "right" way as you say and its all down to builders preference. Looking on line I have seen all 4 ways used. Your post however puts forward a good case for 1. above in this application and I tend to agree with you.

 

I am going to be looking at every wheel I see now checking out which technique wheel builders have used

 

Regards

 

Jerry

Edited December 27, 200916 yr by jerrysimon

I am going to be looking at every wheel I see now checking out which technique wheel builders have used

 

Regards

 

Jerry

 

Yes - I also found that I looked at a lot of wheels after getting interested in the subject.

 

James

Ok 2hrs+in the workshop and I think I am done.

 

Firstly as per advice I put some pressure on the spokes from the outer flange to make sure they came in at 90% rather than bowing out.

 

http://farm3.static.flickr.com/2644/4218575853_24219930db_o.jpg

 

This made quite a difference and in fact these outer hub flange spokes loosened off a little, whereas before as I said they had a little tension in them and bowed out.

 

Next I used my electric screw driver to draw up each nipples to about two threads showing certainly saved some wrist ache!

 

http://farm5.static.flickr.com/4007/4219321956_f5f023f268_o.jpg

 

A couple of threads showing

 

http://farm5.static.flickr.com/4022/4219322278_1f76689183_o.jpg

 

I then went round the wheel squeezing the spokes in pairs to de-stress everything.

 

Next in the stand it goes. The stand makes easier work of things and as I got it cheap it was well worth it.

 

http://farm5.static.flickr.com/4046/4218554931_5e4c94701e_o.jpg

 

This is kinda where I began to go wrong. I started tightening everthing up so no threads showed. I forgot to check the tension of the spokes by pinging them and only realised that I had over tightened everything when the nipples started to groan as they rotated in the rim holes. When a nipple eventually split I knew I had gone too far!

 

I also noticed at this point truing was all over the place with the hub dished to one side.

 

I loosened everything back off to a few threads showing and then tightened each until the ping sounds was equal in each spoke. I used my exisitng Brompton front and back wheels as a reference sound. I noticed that these smaller wheels have a higher ping sound compared to my larger 700c Cytronex wheel.

Edited December 27, 200916 yr by jerrysimon

Once I had all spokes with tension in them I again squeezed them all in pairs and then started truing up using 1/4 turns where necessary. To be honest before this everything was pretty close and it needed little ajustment.

 

Now most the nipples have their thread hidden but one or two still showed the odd thread or two

 

http://farm3.static.flickr.com/2719/4219321802_16ba21c88e_o.jpg

 

I checked a spare loose spoke with a nipple and I could do 18 full turns before the nipple would lock up tight. To the end of the thread is about 12 full turns so the least number of turns on any of my nipples will be about 10 full turns.

 

To be honest I think I got too intense about the whole process and probably the easiest thing would have been to get the spoke tension right first using the "pinging spokes technique". As I said after I did this, the wheel was pretty true anyway and I only needed some minor adjustment to get all three truing directions right. I think I followed the book/instructions to the letter and that maybe building these smaller wheels is less precise and not about following exact instructions, but more using your ear and eye once the spokes are up to tension.

 

Anyway by this time it was getting late so it will be tomorrow before I can fit the tyre onto the wheel and try everything out.

 

Regards

 

Jerry

Edited December 27, 200916 yr by jerrysimon

 

I noticed that the smaller wheels have a higher ping sound compared to my larger 700c Cytronex wheel.

 

Just like a piano or a harp, the shortest strings will produce the highest frequency sounds at any given tension.

.

Thanks flecc.

 

Do things look about right from what I have explained/showed above ?

 

PS I realise that it is probably hard to say without actually seeing the wheel in the flesh so to speak. This has certainly been an adventure lol

 

Jerry.

Edited December 27, 200916 yr by jerrysimon

Looks good from here, Jerry.

 

Out of interest, how far did the spokes reach into the nipples. If the tip of the spoke reaches somewhere between the bottom of the slot in the nipple and flush with the top, then the spoke length is ideal.

 

Always worth noting at this stage whether you would once again use exactly the same length of spoke, or a bit longer or shorter. Very useful information for others building that motor into that rim !

 

James

Thanks James,

 

Some just below, some level with the bottom of the slot so as you say in retrospect, I think maybe a mm or two longer would be worth while. The spokes were 18mm so maybe 20mm. *** Edit 118mm so maybe 119/120mm.

 

That said the holes in the hub flange are not drilled perfectly central either.

 

Regards

 

Jerry

Edited December 27, 200916 yr by jerrysimon

Looks good to me as well Jerry. Much of the secret is taking care and checking at each stage, and you've done

that in plenty. I can't see the finished wheel giving you any trouble.

.

Thanks James,

 

Some just below, some level with the bottom of the slot so as you say in retrospect, I think maybe a mm or two longer would be worth while. The spokes were 18mm so maybe 20mm.

 

That said the holes in the hub flange are not drilled perfectly central either.

 

Regards

 

Jerry

 

Would that be 118 / 120 mm ?

 

James

Edited December 27, 200916 yr by JamesC

Oops corrected lol

 

Jerry

It's a good idea JamesC. I obtained the spoke length from a mathematical formula, but there can always be minor discrepancies with the real world. Mind you, that length was not only fine for my Tongxin build, but was also used successfully by another DIY'er on his 80mm-wide Tongxin hub motor.

A possible difference in the spokes fit could come from a slightly different hub construction: after all Jerry received a rather different model than the ones we have used so far.

Cheers, Dan

Edited December 27, 200916 yr by daniel.weck