Wheel Building - Tongxin in Brompton wheel

[daniel.weck]

Do you have a link to the german thread ?

I can't find it anymore, but here is a guy who has removed the outer-case of the Tongxin hub motor to fit on a bracket to drive the chainring (crankset):

eBike mit Tongxin als Kettenantrieb - Seite 36 - Pedelec-Forum

 

[daniel.weck]

I can't find it anymore...

Here it is:

Tongxin Sammelbestellung da? - Seite 3 - Pedelec-Forum

++
Dan

 

[jerrysimon]

Damn those German Pedelec guys are good

I am almost tempted to take mine apart and shorten the shaft, but I won't as it works fine and I don't want to ruin it

Thanks Dan real interesting reading!

Regards

Jerry

 

[daniel.weck]

I took it really slow taking off metal evenly from each side of the fork lug both sides of the the fork. I used my dremel to open up the fork lugs to 10mm

..or drill the axle instead

Untitled Document

 

[jerrysimon]

Interesting Dan. I think I prefer to cut the fork lugs back, though I guess this would make it easier to refit the old wheel back into the original forks.

Regards

Jerry

 

[jerrysimon]

Well I found the post where the German Pedelec forum received their bulk buy which I piggy backed onto.

Seems like one or two of them where also surprised with the roller brake fitting

Google Translate

Dan I was thinking about the picture you showed above and whilst narrowing the shaft on the solid shaft side might be ok, the other side is hollow where the cable exits so surely that would compromise the strength somewhat

Regards

Jerry

 

[jerrysimon]

Any would be EBrompton owners that are planning a DIY wheel build, note that the only stockist in the UK of Sun 36 Hole - 16 * 1 3/8 / 349 rims has just got some in after a wait of 3 months.

Sun CR18 16 x 1 3/8 / 349 Side Wall Rim 36 Hole

I just ordered a spare

Regards

Jerry

 

[jerrysimon]

A short update. Although the Sun CR18 rims are very nicely made and very robust they are just a nightmare to get Marathon Plus tyres on and off. Although after a bit of practise it can be done its almost impossible to get the tyre off without damaging the rubber covering the wire bead.

I have had to remove the tyre a couple of times. I guess other tyres are easier but not much.

Anyway in my current obsession with Moulton bikes I have come across Brian, another wheel builder and he has supplied me with Brompton 16" rims drilled with 36 holes. Brompton rims are usually only 28 holes which are no use as most hub motors are 36 hole. SJS are now selling blank Brompton rims here

Brian will drill this for you with 36 holes if you ask him. He is happy for me to give out his contact details.

Take a look at his web site, its also very interesting especially if you are into small wheeled/classic bikes and has some wheel building info.

Anyway here is one of my Tongxin motors laced up into a newly drilled rim.


bromptontongxin by Jerrysimon, on Flickr


The Marathon Plus tyre took me less than five minutes to ge on the rim

Regards

Jerry

 

[daniel.weck]

Although I love the Sun Ringle CR18 rims for their design strength and manufacturing quality, I must concur with you...

At first I used plastic-coated tyre levers with a steel inner core, but the plastic snapped at the tip and in the process pierced the tube (I should have purchased Schwalbe AV4 tubes in bulk order...would have been cheaper !)

Now I'm using a combination of various types of tyre lever, including the famous VAR tyre lever. Still, quite a stressful job that gradually damages the tyre bead, revealing the steel cable.

 

[Pedalo]

Hi Jerry,

I notice on this wheel you've gone back to building with the pulling spokes on the outside of the hub.

I laced up my wheel last night following the Roger Musson book to the letter and ended up with the same pattern. I'm sure it doesn't make much difference either way.

A short update. Although the Sun CR18 rims are very nicely made and very robust they are just a nightmare to get Marathon Plus tyres on and off. Although after a bit of practise it can be done its almost impossible to get the tyre off without damaging the rubber covering the wire bead.

I have had to remove the tyre a couple of times. I guess other tyres are easier but not much.

Anyway in my current obsession with Moulton bikes I have come across Brian, another wheel builder and he has supplied me with Brompton 16" rims drilled with 36 holes. Brompton rims are usually only 28 holes which are no use as most hub motors are 36 hole. SJS are now selling blank Brompton rims here

Brian will drill this for you with 36 holes if you ask him. He is happy for me to give out his contact details.

Take a look at his web site, its also very interesting especially if you are into small wheeled/classic bikes and has some wheel building info.

Anyway here is one of my Tongxin motors laced up into a newly drilled rim.


bromptontongxin by Jerrysimon, on Flickr


The Marathon Plus tyre took me less than five minutes to ge on the rim

Regards

Jerry

 

[daniel.weck]

I'm pretty sure that consistency (symmetry) is more important than religiously following the trailing/leading spoke arrangements recommended by X.

 

[jerrysimon]

Hi Jerry,

I notice on this wheel you've gone back to building with the pulling spokes on the outside of the hub.

I laced up my wheel last night following the Roger Musson book to the letter and ended up with the same pattern. I'm sure it doesn't make much difference either way.

Just caught up with this. Yes I went back to Roger's book when I built this one to remind myself and ended up with the puling spokes on the outside as you said. Back when I built my first I thought there was only one way and used Sheldon Browns pages and copied my Cytronex wheel which had pulling spokes on the inside. If I had started on the non drive side they would have been the opposite. If you look through Roger's book you will see he lists the various possibilities and as Dan says its does not really matter as long as you are consistant. I found re-reading his book after building a few wheels much more imformative than the first read.

Having said I am not sure if even that is important to be consistant on both sides. I have looked at a lot of wheels recently and notice some even swap pulling spokes on the outide on one side of the wheel and on the inside on the other side of the wheel

The primary thing I am learning about building a good wheel is to prepare the wheel first that is getting all the spokes so they are just in tension first i.e. no spoke doing nothing. Then do a rough check on latteral truness then at an early stage get radial truness right. Its pretty much impossible if you leave radial truness to the end. Its then just a case of tightening everything up going round the rim in sequence turning all the nipples the same amount, doing a few spoke stressing operations (grabbing parallel pairs of spokes and clenching them) as you go and then your pretty much done.

Actually its amazing how tru the wheel is at the beginning if you get the right spoke lengths and prepare the wheel properly. It may sound silly, but the wheel almost builds itself even dishing seems to sort itself out on its own.

The first time built a wheel at the beginning of this thread I found myself locked into what I thought was a precise process. Now I find myself building wheels almost by feel. Its really quite a rewarding experience and gives you a great sense of achievement when you finally fit the tyre, the wheel and take it out for a spin

PS Pedalo keep us updated on progress and we will want to see pics! I will be interested to see how you do the controller and battery installation.

Regards

Jerry

 

[daniel.weck]

I also built my wheels and approached the rim truing process by "feeling" the spokes tension, particularly using sound (pinging spokes using my guitarist nails ) Then of course, I also used a truing stand - or in my case a similar device using a fixed point in space to observe lateral offset as well as radial deviance (at the circumference level) ... my highly-sophisticated truing stand was in fact ... the forks of the bike hosting the wheel (I used the brake calipers to precisely align a fixed reference point along the rim edge)

 

[Pedalo]

The primary thing I am learning about building a good wheel is to prepare the wheel first that is getting all the spokes so they are just in tension first i.e. no spoke doing nothing. Then do a rough check on latteral truness then at an early stage get radial truness right. Its pretty much impossible if you leave radial truness to the end. Its then just a case of tightening everything up going round the rim in sequence turning all the nipples the same amount, doing a few spoke stressing operations (grabbing parallel pairs of spokes and clenching them) as you go and then your pretty much done.

PS Pedalo keep us updated on progress and we will want to see pics! I will be interested to see how you do the controller and battery installation.

Yes I agree. Wheel building does seem to work well if you start out with all the spokes balanced with no tension and tighten everything evenly. Only minor adjustments required after that. I can see that without this key bit of knowledge it would be easy to get into a wobbly mess by tightening everything up straight away and then try to correct gross errors on a tight wheel.

I will do a write up of my build at some point. I've not got very far yet - still got quite a few bits and bobs to buy. I stopped buying stuff when I thought the motors might not turn up. I think it will probably still take me a few weeks to get there but I'm in no hurry. BTW am I right in thinking that to post photos on this forum I need to find another site to upload them to and then I just link to them from here?

 

[jerrysimon]

BTW am I right in thinking that to post photos on this forum I need to find another site to upload them to and then I just link to them from here?

You use to be able to upload pics but they are/were pretty restrictive on size.

I now use flickr and have so many pics there (free up to 200) I have had to sign up and pay for an account.

Flickr gives you a link to code to imbed the picture into your forum post.

Here is an example... One of Sturmey Archer's newest releases the S2C (kickback) hub. I have just laced it into a specially drilled (36h) Brompton rim. Pedal back slightly and you change up or down the two gears, pedal back hard applies the coaster break. No rear brake, brake handle or brake and gear cables required



Non drive side by Jerrysimon, on Flickr

This is a new reworking of the very popular Fichtel & Sachs Duomatic made popular in the 60s/70s. A great compromise for the current very popular fixie.

Regards

Jerry

 

[daniel.weck]

Great stuff Jerry !

By the way, check how loose and wrongly-laced these spokes look:

http://sunlova.com/Images/Item/ESL20AF01_Motor.jpg



That's from an 8-Fun branded, Sun Lova e-bike:

http://sunlova.com/Images/Item/E-8F20AF01BL_T_1.jpg

 

[jerrysimon]

OMG

I had to look two or three times till I realised what was going on. Why bother using both sides of the hub flange when one side will do. Puts a whole new slant on the concept of radial spoking

PS looking closer it is harder to see if they have spoked to the correct side of the wheel rim or not ?

Regards

Jerry

 

[daniel.weck]

Well, on 20" rims, there is no excuse: the spokes are long enough to lace correctly, that is to say by crossing over to maximize the tension, i.e. by alternating trailing and leading spokes on either side of the hub flange.

 

[apshamlton]

A few comments from Freedom Ebikes

Hi Jerry, Daniel et al.
Freedom Ebikes has been a bit quiet on this forum while we've been busy growing the business and getting large amounts of stock to avoid the problems others have had with supply.

I have a few comments on Daniel's build given that he's done for himself quite similar what we supply as a complete kit.

1) Re the spoke lacing of tonxgin into 16" Brompton rim: Freedom Ebikes started out radial, moved to cross and then moved back to radial after Ian Sims of Greenspeed (a world expert in small wheels) confirmed in A to B magazine that a radial build was the best option for a 250watt hub motor in a 16" wheel.
A lot of people have done a cross because of what is written on Sheldon Brown's site but it seems clear that he was talking about larger wheels and (importantly) the more powerful (500 - 750 watt) motors allowed in the US.

2) The Sun Ringle rims are excellent but difficult to get some tyres onto. The solution is just good quality metal tyre levers.

3) We have large supplies of tonxgin motors, controllers, throttles and 36 hole 349mm (16") rims and high quality A123 battery packs direct from A123 itself for do-it yourselfers

4) We also have complete Freedom Ebikes kits with motors built into 16" 20" and 26" wheels with by if you want achieve Daniel's result without all the work.

Regards

Andrew Hamilton
Freedom E-Bikes - Home

 

[daniel.weck]

Hi Jerry, Daniel et al.
Freedom Ebikes has been a bit quiet on this forum while we've been busy growing the business and getting large amounts of stock to avoid the problems others have had with supply.

Hi Andrew, good to hear that your business is in good hands !

I have a few comments on Daniel's build given that he's done for himself quite similar what we supply as a complete kit.

Just to clarify: actually it is Jerry Simon's various DIY jobs that are closer to the Freedom EBike kit.
Although I now ride a lightweight Tongxin-powered Brompton, it initially started as a heavy-duty Suzhou Bafang (8-Fun) workhorse.

1) Re the spoke lacing of tonxgin into 16" Brompton rim: Freedom Ebikes started out radial, moved to cross and then moved back to radial after Ian Sims of Greenspeed (a world expert in small wheels) confirmed in A to B magazine that a radial build was the best option for a 250watt hub motor in a 16" wheel.
A lot of people have done a cross because of what is written on Sheldon Brown's site but it seems clear that he was talking about larger wheels and (importantly) the more powerful (500 - 750 watt) motors allowed in the US.

Well, you are making a good point about small versus large diameter rims. However, this is not the only parameter. You are well-aware that the small 16" rear wheel on a Brompton isn't laced radially, whereas the front one is. The reason of course, it that the rear hub is subjected to high levels of torque originating from human power. The sets of crossed spokes distribute these forces from the center of the wheel onto the rim itself, more effectively and more reliably thanks to the leading/trailing spoke layout.

Now, electric hub motors provide various levels of power and torque, the Tongxin being one of the weaker designs. However there are still significant forces at play. Furthermore, the spoke length with a Tongxin is greater than, let's say, with a Suzhou Bafang (8-Fun) or a Crystalite motor. In the case of direct drive motors, the spokes are so short that the bend at the point of crossing would actually create local stress, potentially leading to failure. In the case of the Tongxin, however, there is plenty of spoke length to lace the rim using a nice, robust crossed pattern.

2) The Sun Ringle rims are excellent but difficult to get some tyres onto. The solution is just good quality metal tyre levers.

Well, based on the experience of Jerry Simon, myself and others, getting the tyre on and off the 16" Sun Ringle CR18 rims (without damaging the rubber-wrapped steel bead) involves strong levers indeed (plastic-coated steel is best) AND some bare-hands technique to get the bead to sit at the bottom of the rim well.

Or, if you're Jerry Simon, you just use standard Brompton rims drilled with 36 holes by SJS

3) We have large supplies of tonxgin motors, controllers, throttles and 36 hole 349mm (16") rims and high quality A123 battery packs direct from A123 itself for do-it yourselfers

Nice. Do you have a price list please ? (website ?)

4) We also have complete Freedom Ebikes kits with motors built into 16" 20" and 26" wheels with by if you want achieve Daniel's result without all the work.

Once again, let's give credits to Jerry Simon and others who have achieved similar DIY Brompton "electrification"

DIY is not for everybody though, so thanks for letting us know about your products ! (I believe there is a trade section in this forum, where you can advertise your kit)

All the best, Dan