pre stressing spokes

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fevitz   10 W

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pre stressing spokes

Post by fevitz » Sep 19 2015 4:00pm

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Ive just respoked a fat tyre wheel for my new motor , it all went very smoothly / no hickups as the calculations of spoke length for the rim and motor at the time were correct when I ordered online :D
Im still putting this project together , last night I raised the front wheel to test power to battery and LCD connections and during the spinning of the wheel off the ground " it felt like it was out of balance " almost as if it needed weights on the rim like a motor vehicle has . Is there any rule to fix this ,,,or is this normal for such a big rim and tyre ? The wheel "doesn't" wobble ,,, left to right as ive done that correctly , but it does feel like it bobs up and down more than it should :roll:
Is there a method for pre stressing the spokes and getting them all evenly tightened to eliminate this ,,,? or is it normal ? :?:

thanks rick

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voicecoils   10 MW

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Re: pre stressing spokes

Post by voicecoils » Sep 19 2015 4:42pm

Lateral true = side to side wobble
Radial true = how round the wheel is

It sounds like you need to work on radial truing.

With radial truing remember that you can't keep working around the wheel tightening spokes indefinitely trying to achieve roundness. At some point you reach max tension and if the wheel isn't round then you need to start loosening specific spokes strategically.

Stress relieving the spokes won't fix this problem but it is something you want to do near the end of a wheel build after you've checked and eliminated spoke windup and corrected and spoke seating issues. It typically involves grabbing pairs of spokes and squeezing together hard to momentarily increase tension.

As for even tension, yes tension needs to be suitably high and relatively even. In an ideal world where your rim and hub were perfect circles and didn't change under force, tightening all spokes to identical tensions would give you a perfect radial, laterally true dishless wheel. But in the real world things aren't precisely round, holes aren't drilled/positioned perfectly etc. So you work to achieve the best compromise of high even tension and trueness. To do it, you need to measure tension. Park TM1.1 is the most popular and commonly used 'affordable' tool.

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Drunkskunk   100 GW

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Re: pre stressing spokes

Post by Drunkskunk » Sep 19 2015 5:03pm

+1. Radial truing is the hardest part most frustrating part of a wheel build. Don't rely on getting the spoke tension even. A perfectly true wheel will probably never have perfectly even spoke tension.


Fat tires are unbalanced. Especialy those spider tires. They are made by Innova, which also make Surly's tires. none of them balance well, but then they were designed for going 5mph across snow, sand, and tree roots at 4-10lbs pressure. Balance doesn't matter in their intended use.

I've found a side benefit to running tire slime in my fatbike is improved tire balance. it's a trick I learned from Jeeps, to balance huge tires that would often get pounds worth of mud and rocks stuck in the treads. Because of precession, the fluid doesn't all go to the heaviest point, it goes to the point 90' around from it. which becomes the new heavy point, causing the fluid to accumulate 90' around from that, and so on, and so on, until it balances. Big trucks have been doing this for decades.
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Ykick   100 GW

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Re: pre stressing spokes

Post by Ykick » Sep 19 2015 5:32pm

Very good replies.

I believe the way to avoid severe radial condition is by paying attention to the number of turns threading each nipple on the spoke. I generally work in 2 turn increments and merely keep track of turns as the wheel pulls shape.

Actual truing must take place and I’m capable of making good radial adjustments. But it’s much easier to clean up a little radial out-of-round than a large amount and counting thread turns (as long spokes are fairly consistent) helps me keep everything close enough for minimal clean-up.
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fevitz   10 W

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Re: pre stressing spokes

Post by fevitz » Sep 19 2015 6:03pm

Why do I get the feeling ill be adjusting the radial only to find ive put the lateral out , then the lateral to find the radial will be out ,,,could be never ending , unless I fluke it ! When I was building this wheel I initially finger tensioned it prior to counting flats when tightening , but as voicecoils says its not going to work in the real world , and drunkskiunk is right about a perfectly true wheel not having even spoke tension .
Does anyone else have a remedy im happy to hear . At least I can check it off the ground and probably 80% improve on it .

thanks rick gold coast australia

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Re: pre stressing spokes

Post by wesnewell » Sep 19 2015 6:12pm

Even if you get the wheel perfectly trued, it's likely to still be out of balance and will bob under higher rpms. You can correct this with weights if you want to just like a car wheel, but I doubt it's worth the effort. Think lead tape or maybe fishing sinkers that clip to the line and a lot of time.
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voicecoils   10 MW

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Re: pre stressing spokes

Post by voicecoils » Sep 19 2015 7:42pm

fevitz wrote:Why do I get the feeling ill be adjusting the radial only to find ive put the lateral out , then the lateral to find the radial will be out ,,,could be never ending , unless I fluke it !
Yep, wheel building is completely iterative. You make changes to radial, lateral, tension & dish then check your work and continue with more radial, lateral, and so on. Ideally each round of adjustments brings the wheel closer to perfection (ie the perfect compromise of adjustments to each variable).

I find it best to make big adjustments at the start and tiny ones at the end (like 1/8th turn of spoke key or less). With practice and experience you'll find you can improve multiple variables simultaneously by choosing the right groups of spokes to adjust together by set amounts. When you get in the 'zone' you'll find you can zero in on a finished wheel fast.

For your situation I would focus only on radial adjustments for a moment and ignore the fact that lateral will go out. When your happy with the roundness, go back to radial and you may well find it easy to make a few small adjustments and pull it back into shape to finish it off.

Last tip is to be aware that over tensioned wheels are 'unstable''. If you happened to have over tensioned your spokes you will find small adjustments can cause big and unexpected changes to the wheel shape. In that situation you need to drop all spoke tensions and start working your way back up again.

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Re: pre stressing spokes

Post by fevitz » Sep 19 2015 8:54pm

Makes good sense voicecoils ,,,,,ill try it ! thanks

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Re: pre stressing spokes

Post by amberwolf » Sep 20 2015 2:41am

fevitz wrote:Why do I get the feeling ill be adjusting the radial only to find ive put the lateral out , then the lateral to find the radial will be out ,,,could be never ending , unless I fluke it !
Do you use rim brakes?

If not, precise lateral trueness doesnt' matter very much.

Radial trueness always matters, unless you are just creeping along all the time. ;)

So go for radial trueness as good as possible, and good spoke tension, and the wheel will be "better" / more usable.

(unless you have rim brakes cuz then the pads may rub on the worst spots).

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Re: pre stressing spokes

Post by fevitz » Sep 20 2015 3:25pm

Thanks everyone , good tips ,,,,,,, , i have disc brakes so so ill bear in mind amberwolf,s suggestion .

rick

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Re: pre stressing spokes

Post by Punx0r » Sep 21 2015 4:08am

Also, avoid perfectionism - If runout is 1mm (40 thou) or less, call it done IMO.

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Ykick   100 GW

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Re: pre stressing spokes

Post by Ykick » Sep 21 2015 6:19am

The single most important thing to do is PRACTICE truing spoke wheels.

Wife’s bike, kid’s bike, neighbor’s bike, junk bike - for a long time I rarely passed a bike wheel that I didn’t throw a tie-wrap on the frame (makeshift runout gauge) grab a spoke wrench and practice a little wheel truing.

One of the best things I’ve ever taught myself having to do with this technology.
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Re: pre stressing spokes

Post by 999zip999 » Sep 21 2015 2:09pm

Pre stress or stress spokes. Before or after and how is this performed. What's are these secrets ?

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Re: pre stressing spokes

Post by fevitz » Sep 21 2015 4:10pm

I ended up getting it real close ,,,within a MM so im happy with that . I also let the tyre down , soaped the beading so it was slippery and pumped air into it making it sit better (and its made a huge difference)
Ykick ,,good advice , the more you do it the better you get at it , Thanks everyone for the input its made all the difference . :D

rick

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cal3thousand   1.21 GW

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Re: pre stressing spokes

Post by cal3thousand » Sep 21 2015 6:05pm

There's lateral true, radial true AND radial balance.

for the former 2, I try to get both done during the later truing stages by making adjustments that help BOTH lateral truth and radial truth. Say one section needs to move left and at the same time, the area is also needs to be looser in radial terms, I loosen the right side spokes a tad. Doing this all the way around (tightening or loosening) at the final stages give a very true wheel. But make sure to keep the spokes as close as possible in tension. Generally, I find that even tension numbers provide a true wheel using new parts. When repairing a broken wheel, it is more likely that varying tensions will give a good result when compared to a new build.

Then, the last part is radial balance. This is an area in which ebikes have not advance very much. There are some people that are balancing tire/wheel assemblies, but I think that is rare since the weight and speed are not yet up to motorcycle levels. For me, I have found that moving the tire around (clocking) can help by spreading out any anomalies in manufacturing; but the return on effort may not be that good.


For stressing spokes, work your way around the wheel and grab parallel pairs of spokes with your hands and give a good squeeze. About as hard as you can before it starts to hurt is how I do it. I'm sure there are more scientific and preferred methods. :D

I usually do the stressing when tight, but before final truing.
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Re: pre stressing spokes

Post by voicecoils » Sep 22 2015 5:34am

999zip999 wrote:Pre stress or stress spokes. Before or after and how is this performed. What's are these secrets ?
This is the best article I've read on the topic: http://www.wheelfanatyk.com/blog/wheel- ... our-wheel/

It's fairly short and worth the read.

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Re: pre stressing spokes

Post by cal3thousand » Sep 22 2015 10:37am

voicecoils wrote:
999zip999 wrote:Pre stress or stress spokes. Before or after and how is this performed. What's are these secrets ?
This is the best article I've read on the topic: http://www.wheelfanatyk.com/blog/wheel- ... our-wheel/

It's fairly short and worth the read.
Great article! Thanks for posting that.
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Re: pre stressing spokes

Post by 999zip999 » Sep 22 2015 4:27pm

Wonderful
But there's 22 different article's. I will need some time. Thanks voilcoils.

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voicecoils   10 MW

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Re: pre stressing spokes

Post by voicecoils » Sep 24 2015 6:21am

999zip999 wrote:Wonderful
But there's 22 different article's. I will need some time. Thanks voilcoils.
The one on stress relieving is only 8 paragraphs long.

Here's the key section from it:
A good example (thanks, Jobst) is the grappling hook used by an industrial crane or derrick. Such a hook is expected to carry huge loads without deforming or wearing out. When it’s formed, a straight section of metal is bent into a “U,” the shape of the eventual hook. However, if the U is over bent a bit and then pulled open to the desired geometry, pent up stress in the metal is relieved. Such a hook is more rugged than one simply bent to shape. The over bent, then opened hook is stress relieved.
Yes the rest site is worth reading too if you have time

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Re: pre stressing spokes

Post by 999zip999 » Sep 24 2015 6:39am

To be a real wheel fanatic.
I hope my tension doesn't cause health problems. You know heart related ect. How does working on your ebike e-fect your health ?
Do you drink more because of ebike tension ? Oh need some stress relief. Just pass the bottle. Can stress relief be cured by the bottle ?
Tip: I found a bent spoke can get the cork out.

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Re: pre stressing spokes

Post by fevitz » Sep 24 2015 9:25am

voicecoils wrote:
999zip999 wrote:Wonderful
But there's 22 different article's. I will need some time. Thanks voilcoils.
The one on stress relieving is only 8 paragraphs long.

Here's the key section from it:
A good example (thanks, Jobst) is the grappling hook used by an industrial crane or derrick. Such a hook is expected to carry huge loads without deforming or wearing out. When it’s formed, a straight section of metal is bent into a “U,” the shape of the eventual hook. However, if the U is over bent a bit and then pulled open to the desired geometry, pent up stress in the metal is relieved. Such a hook is more rugged than one simply bent to shape. The over bent, then opened hook is stress relieved.
Yes the rest site is worth reading too if you have time
There really is a lot involved ,,, its an art form . :idea:

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Re: pre stressing spokes

Post by 999zip999 » Sep 24 2015 12:12pm

Order 80 13/14 spokes and two alxe dm24 -26" rims. Still have some reading.

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