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Old 08-19-12, 03:43 AM   #1
anathemic
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need help with spoke lenght

hey guys..i am from turkey..i am building a par wheel for my new singlespeed classic.

so here is my calculation.



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but the problem is,there are only 285mm and 290mm spoke lenghts where i live..

so i decided to go 4 cross for front wheels which needs 290mm..and i ll be ok with it.

but for rear,with 4 crosses left is 287.5 and right 288.6..

so do you thing its possible to lance the rear wheel with 290mm spokes ?..my rim is double wall..
will it be possible to dish the wheel with same spoke lenghts on both side ?..

hope i could tell my problem with my poor english..
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Old 08-19-12, 05:36 AM   #2
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but the problem is,there are only 285mm and 290mm spoke lenghts where i live..
Why not buy them online?

Or, you could get yourself a thread roller... I just rebuilt my front wheel with some sweet bladed (2.0x1.4) Wheelsmith spokes that were 8mm too long... but free

...I was able to tighten the 14g head enough to do 15g
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Old 08-19-12, 07:51 AM   #3
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well..i'dont think i can find a thread roller here..even the bike shops doesn't have it so they can resize spokes.

i just wonder if 290mm spokes both size is usable for my rims ?
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Old 08-19-12, 08:40 AM   #4
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You can almost certainly (build the front 4x using 290mm spokes, so start there. Based on where the spokes come out you'll know how much room you need for them to come another 2mm or so higher. Thread a nipple down a spoke and see if there's enough thread for them to do so. If so, you're good to go, if not here's a trick that can bail you out. Find a 2mm drill, and carefully drill out the thread relief of the nipples another 2-3mm deeper. I'm referring to the section of the nipple opposite the head.

This will let the nipple thread farther down the nipple allowing the use of the longer spokes.

Drilling the nipples is a pain but if you have a power drill is fairly quick. Hold the drill in a vise, and gently feed the nipples hand holding them. Don't worry about loss of strength since all the thread strength comes from the 2-3mm in the head of the nipple.
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Old 08-19-12, 10:12 AM   #5
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aha i think i got it..so you mean,to drill and make the end of nipples 2mm larger so that hey can go down and cover a bit more of the spoke's thread..and this will give me more space to tension the long spoke..

did i get it wrong ?..

if not its a tricky but genius solution..but i am afraid if the nipples cracks while during drilling..worth to try

thanks you mate so much..
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Old 08-19-12, 10:20 AM   #6
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aha i think i got it..so you mean,to drill and make the end of nipples 2mm larger so that hey can go down and cover a bit more of the spoke's thread..and this will give me more space to tension the long spoke..

did i get it wrong ?..
No, I think you got it. You drill from the end opposite the head, removing a few threads from that end.

BTW- If you don't have the drill you can usually do the same job by simply forcing each nipple down onto an oiled spoke held in a vise to control twist. Make sure to go beyond what you need by a turn or two because you don't want to be forcing the nipples while coming to final tension. You can do it but you'll get tremendous spoke twist.
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Old 08-19-12, 10:25 AM   #7
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ok i got it..thank you.

let me ask a final thing

when ur calculated spoke lenght is (for example 290mm)..and u lance the wheel witht it,and tune it...u run out of every thread ? or u have still threads to go for more tension ?..
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Old 08-19-12, 10:48 AM   #8
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ok i got it..thank you.

let me ask a final thing

when ur calculated spoke lenght is (for example 290mm)..and u lance the wheel witht it,and tune it...u run out of every thread ? or u have still threads to go for more tension ?..
With ideal length spokes, the screwdriver notch in the nipple should be free with spokes properly tensioned. That means you still have 2-3 mm of threads left, more in some cases.
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Old 08-19-12, 10:58 AM   #9
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so we can say,probably i can dish my rear wheel using with same lenght spokes with a bit of luck ? while the drive side should be 1mm longer.
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Old 08-19-12, 11:01 AM   #10
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Originally Posted by anathemic View Post
ok i got it..thank you.

let me ask a final thing

when ur calculated spoke lenght is (for example 290mm)..and u lance the wheel witht it,and tune it...u run out of every thread ? or u have still threads to go for more tension ?..
IMO, the ideal length for a spoke is one where it engages about 2mm into the head of the nipple. I think of nipples as a nut (the head) and an extension for convenience in lacing and aligning (the rest of the nipple). Since most nipples aren't as strong as the spokes (15g spokes and brass nipples are close) Only the engagement in the head provide full strength, and the guidline for all screws and nuts is engagement equal to the diameter of the screw, ie. 2mm.

So that's my target. Spoke calculators will wield different answers for the same data, because they compensate for some of the subtle variations, like whether you used a rim ERD value measured to the base or top of the nipple. So I always make my own measurements and use the same calculator to ensure consistent results. The way I do it gives results that are consistently up to 1mm short of my target so I allow for that in rounding and buying spokes.

Lastly, thread length on spokes and nipples varies, with some combinations allowing the spoke to go beyond the top by 2mm or more, while ithers can barely reach the top of the nipple before running out of thread. I'm careful to stay with nipples I know, or test by threading on a spoke to know where the limit is.

That's why I suggested building the front first. It's the closest to 290 by the calculation, and because all the spokes are the same length will be the most forgiving of a variation. Where the front ends up will help you predict what, if anything, you'll need to do so the rear works out also. Since I like to target full engagement into the head of the nipple, I make sure I have the ability to go 2mm beyond, just in case.
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Old 08-19-12, 11:05 AM   #11
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so we can say,probably i can dish my rear wheel using with same lenght spokes with a bit of luck ? while the drive side should be 1mm longer.
The drive spokes will come 1-2mm higher in the nipples than the left. Nothing you can do about that, so the room you have for error is narrowed. Spokes too long the right will come too high, too short, the left won't engage the head by enough, though there's some forgiveness here since the left side has about 2/3s or less, the tension of the right.

Build the front, see where the spokes end up, then you can predict how the rear will work out. With luck, you might not need to do anything special.
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