Spoke Strentgh (My spokes are breaking like mad...)

[betarambo]

I strung up my MP3 to a 14" motorcycle wheel. I think this might be the shortest spokes anyone has done on a hub motor. They are under 1" long.

Well done.

How did you get 1" spokes? The shortest anyone has been able to cut for me has been about 65mm.
Chalo

I found a guy who had modified his spoke machine so he could make shorter spokes for hub motor projects. Dave at http://www.dggreenproducts.com
I wasn't sure how it was going to pan out so I asked him to cut the spokes to 1 1/8" and make the threaded portion twice as long as normal. This gave me some options as I messed with spoke patterns. I ended up changing from a 28 spoke wheel to a 32. (I am ashamed to say not for the increased strength but because I found a blue anodized one on ebay cheap and I wanted it pretty). Once the wheel was true I cut the excess spoke material and ground them smooth with a die grinder. Note that a nipple with a hex end was critical here as a spoke wrench would not fit in the gap and you can't get to the nipple anyway as bicycle nipples are too short to poke through the dimples in a motorcycle rim. (I know, this means I have to remove the tire if I want to tighten spokes, but I think that is livable) This problem might happen even on a bicycle because the Belleville washers take up some room. Also keep in mind that the washers make the nipple stick out more inside the wheel so you need to spend more time making sure they are smooth and you need a little extra rim band. I used three passes of electrical tape and then put a motorcycle rim band on. We will see how it holds up.
Spoke with washers and nipple as used:

Nice work.

However, it makes you wonder what the tensile strength is of such short spokes. But for the issue at hand, this was probably the easiest way forward.

Like Chalo said, the tensile strength is only defined by the diameter of the spoke. The short length should make them harder to bend but I don't expect that to have any real advantage since (as established on this thread) the strength of the wheel all comes from tension with conventional spokes.

Farfle, cool project. I am guessing that is a 16" motorcycle wheel? I had considered going with something like your design, but this is a bike for my kid and I plan to keep making it bigger as she gets bigger so being able to upgrade to bigger rims in the future is important to me.

 

[johnrobholmes]

The shortest I can go on my machine is 45mm, but I want to know how he got the double length threads!

 

[Drunkskunk]

Those look like cut, not rolled threads. maybe thats how they got the extra leingth?

 

[nicobie]

Those look like cut, not rolled threads. maybe thats how they got the extra leingth?

yea

 

[voicecoils]

The shortest I can go on my machine is 45mm, but I want to know how he got the double length threads!

Which machine are you using?

On the Hozan C-700, you can keep rolling any length of threads you want if you drill a spoke-sized hole through the die-head holder / handle connecting rod:

But, it can only do 14 and 15G spokes and is time consuming to use.

 

[voicecoils]

I strung up my MP3 to a 14" motorcycle wheel. I think this might be the shortest spokes anyone has done on a hub motor. They are under 1" long.

Well done.
How did you get 1" spokes? The shortest anyone has been able to cut for me has been about 65mm.
Chalo

We just received our new spoke machine at my shop, it's the Morizumi and it will roll threads pretty darn short. I tested it on some 13G spokes today but it does 15,14,13 & 12G:

The top spoke is the shortest length the machine's cutter will do, without removing the cutting guide. A bit under 45mm.
The bottom spoke is the shortest that will fit in the machine's thread die plates but must be hand cut first. ~27mm.

 

[nicobie]

Wow!

At $3,200 it's a bit rich for me.

http://stores.ebay.com/Wheel-Fanatyk/Morizumi-Spoke-Machine-/_i.html?_fsub=206130018

 

[betarambo]

I got my spokes made by Dave at DG Green Products in Florida. http://www.dggreenproducts.com
They are about an inch long. He does good work and really stepped up with the warranty support on my pie. I don't think he comes on this forum but I would think he would be happy to talk to anyone about how he makes them and also happy to make spokes for people.

I have now strung up my 14" motorcycle rim to the pie twice with the same spokes. Once on a MP3 and then later on a MP2 after the 3 had issues. Both times the guy at the bicycle shop who trued it for me said he thought the Bellville washer idea you gusy came up with really allowed him to get some tension into them. My kid has several hours on it now with a lot of jumps and rocks with no problems at all. Obviously time will tell but so far things are perfect.

Thanks for the cool collaboration that lead to the great idea that I shamelessly stole!

 

[the12be]

hi you re problem is probably caused by your wheel size you can buy smaller wheels without spoks

conhismotors and other site i have added a link to conhismotor

http://www.conhismotor.com/Diy_eBike.asp

ps if anyone can help me with a problem i have ?

 

[amberwolf]

ps if anyone can help me with a problem i have ?

People tried, but you haven't bothered to reply to their questions or suggestions in your thread.

 

[betarambo]

by the12be » Thu Sep 13, 2012 12:26 pm

hi you re problem is probably caused by your wheel size you can buy smaller wheels without spoks

conhismotors and other site i have added a link to conhismotor

I don't think it is a "problem". It was a "challenge" which is now solved. The smaller rims without spokes you are talking about will not work for me. I need motorcycle rim sizes and all of the cast wheels are for bicycle sizes.

 

[liveforphysics]

Pro-tip with spokes:

Wrap them all around the hub, along with the drive chain at 60mph.

 

[Ykick]

Holy crap... Wearing leather, I hope?

 

[liveforphysics]

Holy crap... Wearing leather, I hope?

http://endless-sphere.com/forums/viewtopic.php?f=3&t=43899

 

[DrkAngel]

My experience has been with the EZip type non-hubmotor wheels. (EZip Wheel Re-builds)

14g to 12g Upgrade

Most all my recommendations are somewhat applicable to all wheels.

Redrilling Spoke Holes

12g

#1 Size of hub holes 1/8".

#2 Size of wheel holes 3/16".


Bonus Section!

#1 Spokes are now stronger than wheel?

You might pull the stronger spokes right through the wheel?
So ... washers!
#10 SAE "stamped" washers have a nice concave side, that seats nicely with 12ga nipples.
Aluminum alloy wheels don't particularly like steel, even zinc coated steel washers, against them, so I ran 2 wraps of duct tape between.
(Stainless steel washers are available.)

Allow sufficient hole sizes so that the spoke has a straight "pull", (no bend near nipple!).

#2 Spokes keep breaking at elbow?
Hub flange too thin? Too much spoke "flex"?
Pull the spoke elbow tight to the "hub flange".
#4 SAE washers work nicely, and look impressive!

Stainless steel washers recommended!

SAPIM STAINLESS 12G SPOKE
Product #435925
$0.35
Great price but limited sizes.

 

[John Bozi]

read a few pages of this thread on the physics, but not quite finding the info I want.

I'm going from a 26" one cross laced rim down to 19" radially laced rim on my 4065 for torque and efficiency reasons.
Can anyone give me a rough figure of how much weaker my wheel area will become? (if craftsmanship and riding is the same)

p.s. edit the spelling in the title?

 

[cal3thousand]

read a few pages of this thread on the physics, but not quite finding the info I want.

I'm going from a 26" one cross laced rim down to 19" radially laced rim on my 4065 for torque and efficiency reasons.
Can anyone give me a rough figure of how much weaker my wheel area will become? (if craftsmanship and riding is the same)

p.s. edit the spelling in the title?

I highly doubt that you will get solid numbers around the subject. Sheldon Brown does a good of a job as any place I have seen in testing theories about wheels and they don't have much objective information on the stiffness NOR strength differences of wheel lacing pattern:

http://sheldonbrown.com/rinard/wheel/index.htm

 

[Tench]

read a few pages of this thread on the physics, but not quite finding the info I want.

I'm going from a 26" one cross laced rim down to 19" radially laced rim on my 4065 for torque and efficiency reasons.
Can anyone give me a rough figure of how much weaker my wheel area will become? (if craftsmanship and riding is the same)

p.s. edit the spelling in the title?

There is no reason at all to go with radial spokes on a 19" rim even with a large motor, I have done 1x laced builds down to 16" rims on 233mm dia motor flanges with no problems. The moto rims accommodate spoke angle very well as they where designed to be laced to larger dia hubs than bicycle rims.
A 1x laced wheel will be much stronger than a radially spoked wheel.

 

[John Bozi]

read a few pages of this thread on the physics, but not quite finding the info I want.

I'm going from a 26" one cross laced rim down to 19" radially laced rim on my 4065 for torque and efficiency reasons.
Can anyone give me a rough figure of how much weaker my wheel area will become? (if craftsmanship and riding is the same)

p.s. edit the spelling in the title?

There is no reason at all to go with radial spokes on a 19" rim even with a large motor, I have done 1x laced builds down to 16" rims on 233mm dia motor flanges with no problems. The moto rims accommodate spoke angle very well as they where designed to be laced to larger dia hubs than bicycle rims.
A 1x laced wheel will be much stronger than a radially spoked wheel.

ready to be surprised?

I mean 19" bicycle rim.

 

[Chalo]

I mean 19" bicycle rim.

Maybe you confused him by saying you were looking for efficiency that way. The selection of rolling stock (observed trials tires) in that size must make it the slowest tire size in the bicycling world. They're basically cushion airbags for obstacle course riders averaging zero-point-something miles per hour. Even street trials riders don't use them, I guess because some feats require you to gather up a little speed first.

Using 20" tires (ISO 406) instead of ISO 387 would give you a selection of rubber including not just fat dirt tires, but high pressure freestyle tires, slicks, moped tires, and narrow tires that offer an even smaller outside diameter than so-called 19" knobbies. Almost all the tire options in 20" are inherently faster than 19" trials tires.

The spoke pattern issues are the same either way, since the difference in spoke length is less than 10mm.

 

[Tench]

I mean 19" bicycle rim.

Maybe you confused him by saying you were looking for efficiency that way. The selection of rolling stock (observed trials tires) in that size must make it the slowest tire size in the bicycling world. They're basically cushion airbags for obstacle course riders averaging zero-point-something miles per hour. Even street trials riders don't use them, I guess because some feats require you to gather up a little speed first.

Using 20" tires (ISO 406) instead of ISO 387 would give you a selection of rubber including not just fat dirt tires, but high pressure freestyle tires, slicks, moped tires, and narrow tires that offer an even smaller outside diameter than so-called 19" knobbies. Almost all the tire options in 20" are inherently faster than 19" trials tires.

The spoke pattern issues are the same either way, since the difference in spoke length is less than 10mm.

Lets face it, I am easily confused! I was not aware there was such a thing as a 19" bicycle tyre! just had a look, there are some nice looking ones. Bit small though?
Spokes, have you had a look at Justins new spoke calculator which now includes the option of paired holes, this would be a far better solution to radial spokes.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=59804

 

[johnrobholmes]

Yes, redrill your hub flange for 0.5 cross paired spokes. Its really the only way to properly build into most bicycle rims with large hub motors.

 

[John Bozi]

I mean 19" bicycle rim.

Maybe you confused him by saying you were looking for efficiency that way. The selection of rolling stock (observed trials tires) in that size must make it the slowest tire size in the bicycling world. They're basically cushion airbags for obstacle course riders averaging zero-point-something miles per hour. Even street trials riders don't use them, I guess because some feats require you to gather up a little speed first.

Using 20" tires (ISO 406) instead of ISO 387 would give you a selection of rubber including not just fat dirt tires, but high pressure freestyle tires, slicks, moped tires, and narrow tires that offer an even smaller outside diameter than so-called 19" knobbies. Almost all the tire options in 20" are inherently faster than 19" trials tires.

The spoke pattern issues are the same either way, since the difference in spoke length is less than 10mm.

cushion airbags for obstacles = I like that. I am not doing jumps of anything with the rear, but I do hit a lot of rocks as I try to climb very steep mountains trails. I never ever would go more than 40kmh on a straight up there, unless I am suicidal. I have lots of spinning tyre over erosion humps, roots, gravel and other loose debri.

Thanks Chalo, was wondering if you were still around es. I appreciate the answer that there would be little difference in patterns at that length.

So as I described my riding style, would you say I'll breaking spokes a lot?

 

[Chalo]

It sounds like what you have in mind for your bike suits the typical 19" tire perfectly.

If you use quality spokes (14ga or 14-15ga), lace them radially or 0.5 cross as JRH suggests, get them good and tight, and stress-relieve them, I don't think you'll have any unusual spoke breakage issues. Use spoke prep, pipe compound, linseed oil, or purple Loctite on the spoke threads so they don't loosen in use.

 

[John Bozi]

If you use quality spokes (14ga or 14-15ga),.

thanks for the other tips but just want to focus on the above.

The 4065 hub flange usually takes 12 gauge and some even put 11/12 ones with the 11 at the flange. Are you saying that 14 gauge is the best to lace a 19" bicycle rim into a 4065 (will be 2.8-2.5k of torque mostly) for the high torque parts.