Road Bike, Cycling Forums banner
1 - 20 of 48 Posts

·
Registered
Joined
·
350 Posts
Discussion Starter · #1 · (Edited)
Ok , I'm working on building a rear wheel, Its a H Plus Son Archtype, with a Dt Swiss 350 road hub. The erd as I measured it using Roger Musson method in his e-book is 592. I have used 4 different spoke calculator's.
1. Prowheelbuilder.com, nds=288.6, ds=287.2
2. Dt Swiss, nds=288.6, ds=287.2
3. WheelPro(Musson site), nds= 288.4, ds=287
4. Bikeschool.com, nds=288.6, ds=287.2

My main question is about rounding the ds number, according to Musson you round up or down up to 1mm to the nearest number, there seems to be a consensus among the calculators, so the ds number is 287, do I need to round down to 286 or round up to 288?
 

·
Premium Member
Joined
·
2,714 Posts
Theoretically, it should not matter. Practically, I would go up to 288mm if I could not get the 287mm.
 

·
Registered
Joined
·
350 Posts
Discussion Starter · #3 · (Edited)
Thanks, dcgriz. I also was wondering if it was unusual for the spoke length for both sides to be the same length considering dish of the wheel. I was going to round down on the nds to 288.
 

·
Registered
Joined
·
350 Posts
Discussion Starter · #4 ·
After triple checking my rim erd, using Roger Musson and Mike T 1st method on his site, I have change it from 592 to 593. So now my spoke length's are, nds=289.1, ds=287.7. The question now is do I round the nds up to 290 or down to 288?, I will round the ds up to 288
 

·
A wheelist
Joined
·
11,324 Posts
Always use the rule-of-thumb for spoke number rounding - "up or down a maximum of +/- 1mm from the calculated length to the available spoke length" (some suppliers only stock odd number lengths and some only stock even number lengths).

The only time I would break this rule is if I was using thin center Laser or Revs - If the calculation was (let's say) 289.1 or 289.2 I'd go down to 288 and not up to 290 if just even lengths were for sale.

But that's me. OOMV.

But if November Dave posts and he contradicts me, go with his opinion as he builds more wheels in a morning than I do in a year.
 

·
Registered
Joined
·
350 Posts
Discussion Starter · #6 ·
Always use the rule-of-thumb for spoke number rounding - "up or down a maximum of +/- 1mm from the calculated length to the available spoke length" (some suppliers only stock odd number lengths and some only stock even number lengths).

The only time I would break this rule is if I was using thin center Laser or Revs - If the calculation was (let's say) 289.1 or 289.2 I'd go down to 288 and not up to 290 if just even lengths were for sale.

But that's me. OOMV.

But if November Dave posts and he contradicts me, go with his opinion as he builds more wheels in a morning than I do in a year.
Thanks Mike T's, I have found a online site(Wheels Manufacturing) that sells in odd and even sizes, So i will go nds=289.1 rounded to 289, ds=287.7 rounded to 288, does this look good to you.
 

·
Premium Member
Joined
·
2,714 Posts
For the most accurate results make sure that you measure all components in accordance to the instructions given by the particular spoke length calculator you are using because results will otherwise differ.
Your 289.1 to 289 and 287.7 to 288 look fine to me assuming you measured the hub flanges as Musson is showing to do since it seems you are using his calculator.
 

·
Registered
Joined
·
137 Posts
I've been rounding down on the short spokes (high tension side), and up on the long spokes (low tension side). If lacing radial heads out, round down. Maybe I've been getting lucky, but it's been working out perfectly.
 

·
A wheelist
Joined
·
11,324 Posts
I've been rounding down on the short spokes (high tension side), and up on the long spokes (low tension side). If lacing radial heads out, round down. Maybe I've been getting lucky, but it's been working out perfectly.
Those are interesting ideas. I wonder what comment someone with the experience of November Dave will have on this.
 

·
a real member's member
Joined
·
3,880 Posts
i'm terrible at measuring erd, so i don't do it. i've been lucky with online erd databases.

i verify my hub measurements using online databases to see if i'm the ballpark. i always use my own hub numbers. then round down all calculated spoke lengths.

and finally, don't worry about it, because it always works out.
 

·
A wheelist
Joined
·
11,324 Posts
i'm terrible at measuring erd, so i don't do it. i've been lucky with online erd databases.
One day there's a good chance you'll get bitten in the arse. It could have happened to me last year but I found a bad ERD within 5 minutes of opening the box. It was 5mm out. The number that was given was the nipple seat diameter. I pointed the mistake out to the maker and they said woops we screwed up. Within hours the figure had changed on one place on their site but not on their .pdf.

Some rims get their spec changed and I wonder how many rim databases or retailers' sites catch the change - and how many make the change.

i verify my hub measurements using online databases to see if i'm the ballpark. i always use my own hub numbers.
And that's the least important measurement by far. You could almost eyeball hub data and be close enough.
 

·
A wheelist
Joined
·
11,324 Posts
Always round down. Being 1mm short won't cause any problems, but being 1mm long can result in the nipples bottoming out on the threads and binding, or having to force the nipples.
So what you're saying is this -

If the calculated length was 281.9 and the spokes were only available in even number lengths, you would go down to 280 and not up to 282? Wouldn't that put the end of the spoke right at the neck of the nipple?
 

·
A wheelist
Joined
·
11,324 Posts
Okay, not always, that's an extreme example. But it's safer to round down 1.5 than up 1.0 when spokes are only available in even sizes.
'Scuse me for being terminally picky with my example but you were the one who wrote "Always round down". There are a lot of newby wheelbuilders who use the info left behind on this forum and they don't need advice that might get them bitten in the arse.

I don't ever remember anything but "+/-1mm" being given as proven advice around here.
 

·
Registered
Joined
·
734 Posts
Always use the rule-of-thumb for spoke number rounding - "up or down a maximum of +/- 1mm from the calculated length to the available spoke length" (some suppliers only stock odd number lengths and some only stock even number lengths).

The only time I would break this rule is if I was using thin center Laser or Revs - If the calculation was (let's say) 289.1 or 289.2 I'd go down to 288 and not up to 290 if just even lengths were for sale.

But that's me. OOMV.

But if November Dave posts and he contradicts me, go with his opinion as he builds more wheels in a morning than I do in a year.
This is what I'd say, yes. We use a Phil Wood spoke machine (best money ever spent) so size to .5mm resolution, but that's possibly a distinction without a difference. If you can only get odd or even lengths, Mike's advice is good. I'd include CX Rays with the default "round down" group.

As soon as we get the page built we'll be selling spokes in 1mm increments to give people access to more precise lengths.
 

·
A wheelist
Joined
·
11,324 Posts
This is what I'd say, yes. We use a Phil Wood spoke machine (best money ever spent) so size to .5mm resolution, but that's possibly a distinction without a difference. If you can only get odd or even lengths, Mike's advice is good. I'd include CX Rays with the default "round down" group.
As soon as we get the page built we'll be selling spokes in 1mm increments to give people access to more precise lengths.
You're in a different position to us home wheelbuilders of course Dave. It's not possible to justify a spoke cutter/thread roller for the wheel numbers most of us churn out. But I get most of my spokes from importer Thorsten and he will cut if necessary. I have never found it necessary and that's why I preach the "+/-1mm" thingamajig. He has cut for me but only when he didn't have the needed length in stock at the time.

Yes with CX-Rays and Laser I stretch (is that a pun?) the rule a bit but most newbs don't build with those spokes from the get-go (at least they don't if they follow my site's warnings).

Edit. Ok this bit just clicked in - "we'll be selling spokes". You gonna be selling all wheel parts?
 

·
Banned Sock Puppet
Joined
·
14,449 Posts
i'm terrible at measuring erd, so i don't do it. i've been lucky with online erd databases.
Russian Roulette!! I was about to go lazy like you with my first build and trust manufacturers databases. My bike shop mechanic as well as most builders on this forum warned against this. Yes, you will get away with this maybe 9 out of 10 times. That one time the number is wrong will lead you to much frustration, extra expense, wasted time and lots of cursing. Do you really want to take the chance? As the saying goes in the carpentry trade "Measure twice, cut once".

I don't ever remember anything but "+/-1mm" being given as proven advice around here.
Exactly. 1mm too long will not bottom out in the nipple.

Now here's the trick question. If calculations come out to say 289.0 and the choices are only evens....288 and 290. Which way would you go? Roger Musson is OK with either choice and I doubt it really matters. Does anybody here have a definite choice?
 

·
A wheelist
Joined
·
11,324 Posts
Now here's the trick question. If calculations come out to say 289.0 and the choices are only evens....288 and 290. Which way would you go? Roger Musson is OK with either choice and I doubt it really matters. Does anybody here have a definite choice?
With me it would default to what Mud said - "round down" but I'd have to add this bit "if the spokes were skinny Laser (or Revs) or CX-Ray". But that's me.

I've only come unstuck with this advice once in living memory (my wife will claim that's 5 minutes tops) and a DS set was too long and a NDS set was too *&^%$* short. Arrgghh. I dug out my meager stash of spokes and finally went with 2x/1x on the rear when I untended to do 2x/2x. I rebuilt that rear wheel about 6 times in 2 days. Arrgghh x2.
 
1 - 20 of 48 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top