HELP! Wheel Building Question for Staggered Spokes
05-28-19, 09:36 AM
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HELP! Wheel Building Question for Staggered Spokes
Good morning,
I am attempting to rebuild a wide rim wheel from a single speed coaster brake hub to a Shimano 3s hub. The rim is 60mm wide and has a staggered spoke hole pattern. The spokes holes are roughly halfway in between the center line of the rim and the outside edge of the rim. When trying to enter measurements into a spoke length calculator, how do I compensate for that? Any information would be greatly appreciated, thank you! Rim I have is very similar to rim linked below.
https://whiskyparts.co/rims/no9_70w_rim
I am attempting to rebuild a wide rim wheel from a single speed coaster brake hub to a Shimano 3s hub. The rim is 60mm wide and has a staggered spoke hole pattern. The spokes holes are roughly halfway in between the center line of the rim and the outside edge of the rim. When trying to enter measurements into a spoke length calculator, how do I compensate for that? Any information would be greatly appreciated, thank you! Rim I have is very similar to rim linked below.
https://whiskyparts.co/rims/no9_70w_rim
05-28-19, 10:24 AM
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Having spoke drillings staggered to the outside is mathematically equivalent to having a narrower flange spacing at the hub by the same amount. So my approach would be to "narrow" the hub measurements for the calculator. In fact, making adjustments at the hub is the only way I know how to accommodate offsets at the rim. 
05-28-19, 10:40 AM
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1. First of all almost all rims have staggered spoke drillings, so SOME of the difference is already accounted for in the calculators, although those are some wide rims.
2. If you have the actual ERD from the rim maker, then the difference is already accounted for.
3. If you're measuring ERD from an actual rim using an accurate method, then the difference is already accounted for.
4. If you're estimating ERD from an actual rim and you're not accounting for the difference - it's a really small difference. The calculator is probably going to give you a value with 0.1mm precision - almost everybody rounds up or down from there to get the next nearest standard size since spokes come in 1mm or 2mm increments. So I suggest just rounding down.
Go ahead and try experimenting with different flange spacings like Thermionic suggested and see how much the results change. I'll bet the differences will still round to the same selection.
2. If you have the actual ERD from the rim maker, then the difference is already accounted for.
3. If you're measuring ERD from an actual rim using an accurate method, then the difference is already accounted for.
4. If you're estimating ERD from an actual rim and you're not accounting for the difference - it's a really small difference. The calculator is probably going to give you a value with 0.1mm precision - almost everybody rounds up or down from there to get the next nearest standard size since spokes come in 1mm or 2mm increments. So I suggest just rounding down.
Go ahead and try experimenting with different flange spacings like Thermionic suggested and see how much the results change. I'll bet the differences will still round to the same selection.
05-28-19, 11:03 AM
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This 60mm rim is significantly staggered. One line of spokes on one side of the rim and another line on the other side (of course). The spoke holes are roughly 11.5mm from the edge of the rim on each side. I do not have the ERD from the manufacturer. I measured ERD the same way I do with standard spoked rims (using 2x 200mm spokes with threaded nipples onto them on opposite sides of the rim and measured the distance in between the two spokes and added 400mm).
Knowing this information - what would I modify in the online spoke calculators? Narrow the flange to center measurement? If so, by how much?
Hell, maybe I'll get the Nexus hub and the hub measurements will be close enough to the single speed coaster brake hub and I'll just order the exact same spoke length. How often does that happen though. Hahah.
Knowing this information - what would I modify in the online spoke calculators? Narrow the flange to center measurement? If so, by how much?
Hell, maybe I'll get the Nexus hub and the hub measurements will be close enough to the single speed coaster brake hub and I'll just order the exact same spoke length. How often does that happen though. Hahah.
Last edited by aaronmichael; 05-28-19 at 11:07 AM.
05-28-19, 11:10 AM
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That's my hunch as well, but with such a wide rim, I wasn't sure. Certainly doesn't make a difference with asymmetric rims that are only off by 2-3mm. 
05-28-19, 11:56 AM
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I had fun making this little graphic that shows what you'd have if you sized for centerline drillings.
Last edited by DiabloScott; 05-28-19 at 12:10 PM.
05-28-19, 12:16 PM
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Oh, and here's a calculator that allows you to enter offset drillings! I'm going to dink around with it a little.
https://www.kstoerz.com/freespoke/
OK using 556 ERD and some stock hubs on a front wheel, 36s 3x:
0mm offset: 258.4mm
23mm offset: 255.9mm
Definitely enough to affect selection for this really wide offset.
https://www.kstoerz.com/freespoke/
OK using 556 ERD and some stock hubs on a front wheel, 36s 3x:
0mm offset: 258.4mm
23mm offset: 255.9mm
Definitely enough to affect selection for this really wide offset.
Last edited by DiabloScott; 05-28-19 at 12:26 PM.
05-28-19, 12:38 PM
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Kind of a rule of thumb-
For about every 10mm difference in spoke flange offset from the hub, your spoke length changes 1mm.
The difference for you, is that you have the angle of the spoke bed to factor in. The greater the difference from the center of the rim, the longer the spoke.
You could maybe use a little Pythagorean Theorem to calculate that.
For about every 10mm difference in spoke flange offset from the hub, your spoke length changes 1mm.
The difference for you, is that you have the angle of the spoke bed to factor in. The greater the difference from the center of the rim, the longer the spoke.
You could maybe use a little Pythagorean Theorem to calculate that.
05-28-19, 12:55 PM
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Here's another issue I'm getting confused with and I think it just comes down to terminology.
Is a staggered spoke rim the same thing as a offset rim? I thought they were the same as first, but everything I've read seems to indicate that an offset drilled rim still has most of the spoke holes inline from one to another, but of course pulled closer to one sidwall as opposed to the other. And therefore, that would be different than a staggered spoke rim. I attached a photo of the rim I'm working with to clarify. Thanks for all the help already!
Is a staggered spoke rim the same thing as a offset rim? I thought they were the same as first, but everything I've read seems to indicate that an offset drilled rim still has most of the spoke holes inline from one to another, but of course pulled closer to one sidwall as opposed to the other. And therefore, that would be different than a staggered spoke rim. I attached a photo of the rim I'm working with to clarify. Thanks for all the help already!
05-28-19, 01:03 PM
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No.
An offset rim has ALL the holes moved over some amount.
4mm in the case of my Velocity Synergy 559mm rim.
Last edited by Bill Kapaun; 05-28-19 at 02:50 PM.
05-28-19, 01:14 PM
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In the Freespoke calculator that was provided a few posts ago, there's a box labeled "Drilling Offset". Would this be the distance from the center of the rim to a spoke hole on either side measured in mm?
If so, that's exactly what I'm looking to incorporate into the calculations.
If so, that's exactly what I'm looking to incorporate into the calculations.
05-28-19, 01:46 PM
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In the Freespoke calculator that was provided a few posts ago, there's a box labeled "Drilling Offset". Would this be the distance from the center of the rim to a spoke hole on either side measured in mm?
If so, that's exactly what I'm looking to incorporate into the calculations.
If so, that's exactly what I'm looking to incorporate into the calculations.
Yes, centerline to spoke hole - it even allows you to enter different values for left and right side offset. See the "how to measure" tab
Offset Drilling
This is the distance from the centerline of the rim to the center of the spoke holes. Freespoke allows left and right values to be handled independently, since not all rims have their spoke holes all in the same plane. This is simplest to measure with the rim laying flat on a good flat work surface. Measure from the work surface up to the eyeballed center of a rim hole, then subtract this value from half of the rim outer width. For example, if you measure 10mm from table surface to center of spoke hole, and the rim is 25mm wide, the math is (25mm / 2) - 10mm = 2.5mm. Note that a positive value indicates right holes more to the right of center, or left holes more to the left of center. If the spoke bed is offset but all in one plane, the values will be the same except one will be negative and one positive. For a rim with holes staggered across the centerline (many fatbike rims), both values will be positive. Two negative values would be highly unusual, and would indicate that the left and right spokes cross the centerline of the rim. I think this is used on a few BMX rims, but that's probably it due to the extreme angles that can quickly result.
05-29-19, 01:15 PM
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Okay, I think I almost have this figured out! Last question I have - using the two spoke measuring method, would I insert the two spokes onto the same side of the rim and measure the distance in between to calculate ERD? Or would I insert one onto one side and one on the opposite side of the rim to measure? Hopefully that makes sense.
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