Spoke length calculator accuracy?
12-18-20, 12:01 AM
#1
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Thread Starter
Spoke length calculator accuracy?
I want to build a set of wheels - never done it before. I plan to use DT swiss 350 hubs 6 bolt QR, 100mm for the front and 135mm for the rear. Rims will be DT Swiss 361 32H and 3 cross lacing. I used this spoke length calculator. This didn't have the 361 in its catalog but it did have the 331. I used that but changed the ERD to 607mm vs. 606mm referencing DT's specs. Nicely enough it gives me 294mm for three sides and 296mm for the non disc side of the front hub. However the 331 is not offset and the 361 is. DT Swiss doesn't give the offset measurement in their specs that I have been able to find so I don't know if it would have any apreciable effect on the spoke length.
I'd appreciate a sanity check before I order parts. Thanks!
I'd appreciate a sanity check before I order parts. Thanks!
12-18-20, 12:56 AM
#2
Really Old Senior Member
Rule of the thumb is 1mm per 10mm of offset.
That pretty much agrees with SpoCalc and the 1 offset rim I've built.
26" Velocity Synergy w/4mm offset.
EDIT-
You're doing just the rear?
Without knowing hub spec's AND rim offset, I'm not sure if you might not be able to go "too far" on a front disc.
Spocalc has an entry box for offset.
That pretty much agrees with SpoCalc and the 1 offset rim I've built.
26" Velocity Synergy w/4mm offset.
EDIT-
You're doing just the rear?
Without knowing hub spec's AND rim offset, I'm not sure if you might not be able to go "too far" on a front disc.
Spocalc has an entry box for offset.
Last edited by Bill Kapaun; 12-18-20 at 01:00 AM.
12-18-20, 06:54 AM
#3
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If you are using DT Swiss components why not use their calculator. https://spokes-calculator.dtswiss.com/en/
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12-18-20, 03:55 PM
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Accuracy is a function of the builder, not the spoke length calculator. The results are only as good as the measurements YOU put into it.
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__________________
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
5000+ wheels built since 1984...
Disclaimer:
1. I do not claim to be an expert in bicycle mechanics despite my experience.
2. I like anyone will comment in other areas.
3. I do not own the preexisting concepts of DISH and ERD.
4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
5. My all time favorite book is:
Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
12-18-20, 04:38 PM
#5
Clark W. Griswold
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I would check it on the DT Swiss Calculator and potentially my favorite the QBP Spoke Calculator. I find it good to check on multiple calculators however if the product is all DT Swiss, you could probably just use theirs as it is should be pretty darn accurate.
12-18-20, 05:09 PM
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+1on checking different calculators. I normally use UBI's which calculates each side if the hub separately and measures from the center of the hub shell to the flange. So far It has served me well for many years. Smiles, MH
12-19-20, 12:45 PM
#8
Senior Member
Figure it yourself.
The Bicycle Wheel by Jobst Brandt (z-lib.org).pdf The formula for spoke length in on page 131.
The Bicycle Wheel by Jobst Brandt (z-lib.org).pdf The formula for spoke length in on page 131.
12-20-20, 09:21 PM
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Figure it yourself.
The Bicycle Wheel by Jobst Brandt (z-lib.org).pdf The formula for spoke length in on page 131.
The Bicycle Wheel by Jobst Brandt (z-lib.org).pdf The formula for spoke length in on page 131.
12-21-20, 12:11 AM
#10
Senior Member
My bad. I'm old and not a computer nerd. My wife is the IT in an old boilermaker's house.
Try this. The Bicycle Wheel | Jobst Brandt | download (b-ok.cc)
Try this. The Bicycle Wheel | Jobst Brandt | download (b-ok.cc)
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12-21-20, 09:44 AM
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Yup, that's the formula I use, though I found it somewhere else. What I like about doing it myself is that it's plain to see where all of the terms come from, and how they relate to the physical dimensions of the components. Basically the mathematical equivalent of "open source." Then I know that I'm not missing anything, and that I understand what I'm measuring. The next thing is doing the measurements myself, because the formula doesn't tell you where you want the end of the spoke to "sit" in the nipple, how much margin you want to allow for variation in spoke length, etc. I keep a notebook with all of my builds, most of which involve a modern rim and ancient gear or coaster hub.
This method has never steered me wrong. A pro builder might be able to skip all of this work and get good results because they've done it so many times, but I do it so seldom that each time is like starting over, and I want to make sure I understand what's going on.
This method has never steered me wrong. A pro builder might be able to skip all of this work and get good results because they've done it so many times, but I do it so seldom that each time is like starting over, and I want to make sure I understand what's going on.
