Go Back  Bike Forums > Bike Forums > Bicycle Mechanics
Reload this Page >

Which way to round to even-numbered length of spokes?

Notices
Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

Which way to round to even-numbered length of spokes?

Old 02-27-17, 09:01 AM
  #1  
bikerbobbbb
Senior Member
Thread Starter
 
Join Date: Jul 2015
Posts: 586
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Which way to round to even-numbered length of spokes?

If my spoke calculation gives me 291mm, but I can only buy 290 or 292mm, which way is better to go, too high or too low?

Or does it not really matter?


Too high would leave more jagged edge of the spoke sticking out, but I'll have a double-walled rim, so it's not a huge concern unless the spoke breaks. I could also probably file that edge down when it's sticking out of the nipple.

Too high also means I might run out of thread to pull the spoke in more.
- Is it possible to buy a spoke with more then 10mm thread on it? Or is 10mm plenty, even for being 1mm off?

Too short means the spoke end might still be in the threads of the nipple, not sticking out. Plenty of thread on the spoke left. Is that a concern if there's spoke lock lube on it?

I'm kind of leaning towards 1mm too short being better. Or it might not really matter for a 1mm difference either way.


Another possibility might be to take a 292mm spoke and file off 1mm, then rethread it if needed. But then I'd need a threading tool which is over $100.
bikerbobbbb is offline  
Old 02-27-17, 09:27 AM
  #2  
sch
Senior Member
 
Join Date: May 2003
Location: Mountain Brook. AL
Posts: 3,973
Mentioned: 12 Post(s)
Tagged: 0 Thread(s)
Quoted: 296 Post(s)
Likes: 0
Liked 122 Times in 94 Posts
Makes no difference really with a double walled rim. On a rear wheel you could use both, with the shorter ones on the drive
side and longer ones on the non-drive side

See also: https://www.bikeforums.net/bicycle-me...confusion.html

Last edited by sch; 02-27-17 at 09:41 AM.
sch is offline  
Old 02-27-17, 09:34 AM
  #3  
Jiggle
Senior Member
 
Jiggle's Avatar
 
Join Date: Jul 2013
Location: Somewhere in TX
Posts: 2,266

Bikes: BH, Cervelo, Cube, Canyon

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
I usually round down because the spokes I use will stretch about 1mm at full tension.

However, I have almost 5mm of extra nipple thread with the nipples I use, so it really doesn't matter. If my spoke lengths are within 4mm for the whole wheel, I just order one spoke length.
Jiggle is offline  
Old 02-27-17, 09:40 AM
  #4  
dabac
Senior Member
 
Join Date: Mar 2008
Posts: 8,688
Mentioned: 46 Post(s)
Tagged: 0 Thread(s)
Quoted: 1073 Post(s)
Liked 291 Times in 218 Posts
Well...
Do you know where in the nipple you're aiming for?
Bottom of screwdriver slot - 1 mm extra is fine.
slight risk of trouble with an 1.5 mm spoke on the DS.
Flush with nipple head - still likely to be fine for 2.0 and 1.8 spokes. Almost guaranteed trouble with 1.5 mm DS spokes.
OTOH If your aim is flush with nipple head, then -1 won't be a problem.
If a spoke is a little long its always possible to add a washer under the nipple or drill out a few turns of thread.
dabac is offline  
Old 02-27-17, 09:40 AM
  #5  
trailangel
Senior Member
 
trailangel's Avatar
 
Join Date: Feb 2014
Location: Pasadena, CA
Posts: 4,793

Bikes: Schwinn Varsity

Mentioned: 22 Post(s)
Tagged: 0 Thread(s)
Quoted: 1891 Post(s)
Liked 669 Times in 391 Posts
Depends on the spoke manufacture. Have you actually measured the spokes?
Some run short and some run long.
trailangel is offline  
Old 02-27-17, 09:43 AM
  #6  
andr0id
Senior Member
 
andr0id's Avatar
 
Join Date: Feb 2009
Posts: 2,522
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 1422 Post(s)
Likes: 0
Liked 5 Times in 3 Posts
Originally Posted by Jiggle View Post
I usually round down because the spokes I use will stretch about 1mm at full tension.
A spoke 1mm lower than the slot is much easier to deal with than an a spoke that protrudes into the slot if you ever need to use a screwdriver later down the road.
andr0id is offline  
Old 02-27-17, 11:34 AM
  #7  
Bill Kapaun
Really Old Senior Member
 
Bill Kapaun's Avatar
 
Join Date: Feb 2007
Location: Mid Willamette Valley, Orygun
Posts: 13,252

Bikes: 87 RockHopper,2008 Specialized Globe. Both upgraded to 9 speeds.

Mentioned: 19 Post(s)
Tagged: 0 Thread(s)
Quoted: 1546 Post(s)
Liked 844 Times in 609 Posts
On a double wall rim, I round up, since a "bit" long won't matter.

You have about 2mm more above the screw driver slot before running out of threads.
The NDS spoke will protrude less, but it also has less tension, so IF it's a TINY bit short, that's the side you want it on.
Bill Kapaun is offline  
Old 02-27-17, 02:21 PM
  #8  
bikerbobbbb
Senior Member
Thread Starter
 
Join Date: Jul 2015
Posts: 586
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 120 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by sch View Post
Thanks.

"So if your objective is to have at least that protrusion, you would always round up. "


It's looking like it's not going to matter either way. Personal preference.

I'm leaning towards rounding up.

If the calcuations give me this....
290.8 NDS
289.4 DS
... then 290 and 292mm. That happens to be what I already bought for the 32 spoke wheel I'm on now. I did think the spokes for a 36 wheel would be slightly shorter. It's less of a difference than I thought, maybe 2mm (whatever it is, I don't care what the current wheel perfect spoke length is now since my current wheel is on death row).

I think a lot of my spokes already protrude just a little. That's been fine. For the inner tube getting punctured, I was thinking a spoke would have to go through the second rim (doubtful? but possible if it's all lined up) but then it also has to go through the rim tape. I imagine the most a broken spoke would do is tap on the rim tape. And then I shouldn't have any broken spokes if it's a wheel build with all new parts and everything is trued and dished.

That could give me the option of using a washer too if I really didn't like how it stuck out.
bikerbobbbb is offline  
Old 02-27-17, 03:55 PM
  #9  
L134 
Senior Member
 
Join Date: Dec 2015
Location: San Diego
Posts: 552

Bikes: 1978 Bruce Gordon, 1977 Lippy, 199? Lippy tandem, Bike Friday NWT, 1982 Trek 720, 2012 Rivendell Atlantis, 1983 Bianchi Specialissima?

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 261 Post(s)
Liked 96 Times in 58 Posts
Do yourself a favor and get ONE of the several different wheel building guides that are out there and follow it step by step. You will wind up with a fine wheel.
L134 is offline  
Old 02-27-17, 08:43 PM
  #10  
Jiggle
Senior Member
 
Jiggle's Avatar
 
Join Date: Jul 2013
Location: Somewhere in TX
Posts: 2,266

Bikes: BH, Cervelo, Cube, Canyon

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 212 Post(s)
Likes: 0
Liked 3 Times in 3 Posts
Originally Posted by andr0id View Post
A spoke 1mm lower than the slot is much easier to deal with than an a spoke that protrudes into the slot if you ever need to use a screwdriver later down the road.
The slotted nipples are so 1980. DT, Sapim, Pillar, and CN all make square drive or torx nipples that will work on all but the shallowest of rims. They will let you go about 4mm past the minimum, which is 8 turns, and are only limited when the unthreaded portion of the spoke bottoms out on the nipple threads.
Jiggle is offline  
Old 02-27-17, 09:21 PM
  #11  
Ronno6
Senior Member
 
Ronno6's Avatar
 
Join Date: Nov 2010
Location: Deep South
Posts: 1,348

Bikes: Cannondale SR's and ST's from the '80's

Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 340 Post(s)
Likes: 0
Liked 42 Times in 19 Posts
Why not purchase from a source that will cut to order in 1mm increments??
Rounding to the next mm is seldom a problem.
Ronno6 is offline  
Old 02-28-17, 02:23 AM
  #12  
Kimmo 
bike whisperer
 
Kimmo's Avatar
 
Join Date: Dec 2009
Location: Melbourne, Oz
Posts: 9,456

Bikes: https://weightweenies.starbike.com/forum/viewtopic.php?f=10&t=152015&p=1404231

Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 1473 Post(s)
Liked 688 Times in 486 Posts
If using brass nipples, round down. If using ally, round up.

The two bad things you're trying to avoid are, being too short to make it through the head so the nipple doesn't break, and running out of thread.

A brass nipple is less likely to break if the spoke's a little short, and if you run out of thread in an ally nipple, you can just mash it for a thread or two, which will help them stay tight.
Kimmo is offline  
Old 02-28-17, 04:53 PM
  #13  
Drew Eckhardt 
Senior Member
 
Drew Eckhardt's Avatar
 
Join Date: Apr 2010
Location: Mountain View, CA USA and Golden, CO USA
Posts: 6,341

Bikes: 97 Litespeed, 50-39-30x13-26 10 cogs, Campagnolo Ultrashift, retroreflective rims on SON28/PowerTap hubs

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 549 Post(s)
Liked 320 Times in 223 Posts
Originally Posted by bikerbobbbb View Post
If my spoke calculation gives me 291mm, but I can only buy 290 or 292mm, which way is better to go, too high or too low?
The one which isn't so long it will bottom if the wheel has a low spot, and not so short it doesn't reach through the nipple head which leads to broken nipples. Consider both your current rims and examples of the same type with slightly larger or smaller ERD.

You're probably better off with longer spokes if you measured your rims, your calculator is aiming for the bottom of the nipple slot, and either you aren't using 1.5mm spokes or the calculator accounted for 1mm of stretch.

In that situation, 1mm extra means they'll end at the top of the nipple with 1.5mm of thread remaining before they bottom, and leave almost 2mm extra so you don't break nipples because they don't reach the head.

With a high spot in the rim (like at the joint), 1mm short of the slot can break nipples especially when they're made of alloy.

OTOH, with 1.5mm cross section drive side spokes you'll get about 1mm of stretch. If the calculator didn't account for that you'll only have 0.5mm before running out of threads drive side and front and would want to go 1mm shorter so with stretch they end at the slot bottom.

Another possibility might be to take a 292mm spoke and file off 1mm, then rethread it if needed. But then I'd need a threading tool which is over $100.
If you want to be spot on to accommodate variations in ERD or whatever, order your spokes in custom lengths for a small upcharge.
Drew Eckhardt is offline  
Old 11-19-21, 09:45 AM
  #14  
CerveloMad
Junior Member
 
Join Date: Jan 2015
Location: UK
Posts: 14

Bikes: Cervelo R5 Di2, Cervelo S5, Cervelo S1.

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by bikerbobbbb View Post
If my spoke calculation gives me 291mm, but I can only buy 290 or 292mm, which way is better to go, too high or too low?

Or does it not really matter?


Too high would leave more jagged edge of the spoke sticking out, but I'll have a double-walled rim, so it's not a huge concern unless the spoke breaks. I could also probably file that edge down when it's sticking out of the nipple.

Too high also means I might run out of thread to pull the spoke in more.
- Is it possible to buy a spoke with more then 10mm thread on it? Or is 10mm plenty, even for being 1mm off?

Too short means the spoke end might still be in the threads of the nipple, not sticking out. Plenty of thread on the spoke left. Is that a concern if there's spoke lock lube on it?

I'm kind of leaning towards 1mm too short being better. Or it might not really matter for a 1mm difference either way.


Another possibility might be to take a 292mm spoke and file off 1mm, then rethread it if needed. But then I'd need a threading tool which is over $100.
I always go for the higher length spoke, then extend the thread if it starts to stiffen up with just the Cyclo rolling head I bought for GB£35 (Amazon Cyclo Rolling Head). I didn't buy the whole tool, as it isn't really needed for the amount of spokes I become involved with and it works a treat without it by holding the spoke in a vice with 2 thin wooden blocks. OK, you can call me a cheapskate if you like.........
CerveloMad is offline  
Old 11-19-21, 10:14 AM
  #15  
mpetry912 
aged to perfection
 
mpetry912's Avatar
 
Join Date: Jun 2009
Location: PacNW
Posts: 583

Bikes: Dinucci Allez 2.0, Richard Sachs, Alex Singer, Serotta, Masi GC, Raleigh Pro Mk.1, Hetchins, etc

Mentioned: 17 Post(s)
Tagged: 0 Thread(s)
Quoted: 249 Post(s)
Liked 241 Times in 138 Posts
I agree. round up. Spokes that do not have full thread engagement in the nip will cause the nip to fracture. True, the brass ones are less fragile. but I round UP to the next MM.

and I measure ERD and spokes. Don't trust published measurements you found on the internets

/markp
mpetry912 is offline  
Likes For mpetry912:
Old 11-20-21, 09:22 AM
  #16  
ted_major
Junior Member
 
ted_major's Avatar
 
Join Date: Oct 2008
Location: Tuscaloosa, Ala.
Posts: 134
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 37 Post(s)
Liked 31 Times in 18 Posts
Originally Posted by L134 View Post
Do yourself a favor and get ONE of the several different wheel building guides that are out there and follow it step by step. You will wind up with a fine wheel.
This looks like the best advice in the thread. Iíve used Roger Mussonís wheel building ebook and found it reasonably priced and easy to follow. (In fact, Iím just about to lace up a pair of wheels with a new dynamo hub this morning.)

FWIW, he recommends rounding to the nearest 1mm, which would round both your 289.4 and 290.8 to 290.
ted_major is offline  
Old 11-29-21, 06:01 PM
  #17  
janthenat
Newbie
 
janthenat's Avatar
 
Join Date: Oct 2008
Location: Northern Illinois
Posts: 47

Bikes: 1995 GT Tequesta

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 18 Times in 7 Posts
Based on the discussion here I'm assuming it would be unreasonable to think I could use 290mm spokes based on the following 2-cross & 3-cross calculations? By the way, I'm using 12mm brass nipples.
Thanks for any input!


Front 2-cross

Rear 2-cross

Front 3-cross

Rear 3-cross
janthenat is offline  
Old 11-29-21, 07:09 PM
  #18  
ThermionicScott 
working on my sandal tan
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Posts: 22,080

Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers), All-City Space Horse (hers)

Mentioned: 95 Post(s)
Tagged: 0 Thread(s)
Quoted: 3644 Post(s)
Liked 2,092 Times in 1,327 Posts
^ I wouldn't use 290mm for any of those, you can do better.
__________________
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
Originally Posted by noglider
People in this forum are not typical.
RUSA #7498
ThermionicScott is offline  
Old 11-29-21, 08:45 PM
  #19  
janthenat
Newbie
 
janthenat's Avatar
 
Join Date: Oct 2008
Location: Northern Illinois
Posts: 47

Bikes: 1995 GT Tequesta

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 18 Times in 7 Posts
Originally Posted by ThermionicScott View Post
^ I wouldn't use 290mm for any of those, you can do better.
Yea, that's kind of what I suspected... dang. I did my original calculations using 28 spokes instead of 32, duh.

In that case does anybody have a box of 100 14g 286mm j-bend spokes to trade me for my 290mm's? ;^)
janthenat is offline  
Old 11-29-21, 09:14 PM
  #20  
sweeks
Senior Member
 
sweeks's Avatar
 
Join Date: Sep 2004
Location: Chicago area
Posts: 2,206

Bikes: Airborne "Carpe Diem", Motobecane "Mirage", Trek 6000, Strida 2, Dahon "Helios XL", Dahon "Mu XL", Tern "Verge S11i"

Mentioned: 21 Post(s)
Tagged: 0 Thread(s)
Quoted: 847 Post(s)
Liked 377 Times in 278 Posts
Originally Posted by ted_major View Post
This looks like the best advice in the thread. Iíve used Roger Mussonís wheel building ebook and found it reasonably priced and easy to follow. (In fact, Iím just about to lace up a pair of wheels with a new dynamo hub this morning.)

FWIW, he recommends rounding to the nearest 1mm, which would round both your 289.4 and 290.8 to 290.
Agree about Musson's book. I've used this one for several years, and it's very clear and easy to follow.

About "rounding to the nearest 1 mm"... 289.4 rounds to 289, and 290.8 rounds to 291.
sweeks is offline  
Old 11-30-21, 10:05 PM
  #21  
ShannonM
Senior Member
 
Join Date: Jul 2020
Location: Humboldt County, CA
Posts: 695
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 320 Post(s)
Likes: 0
Liked 313 Times in 216 Posts
Originally Posted by sweeks View Post
About "rounding to the nearest 1 mm"... 289.4 rounds to 289, and 290.8 rounds to 291.
True, but the parameters of the question rule out odd-numbered lengths, so "rounding to the nearest 1 mm" should be read as "rounding to the nearest even 1 mm," even though that phrase doesn't make literal sense.

This generalizes. The most common way to arrive at the wrong answer is to start from the wrong question.

--Shannon
ShannonM is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
totalnewbie
Bicycle Mechanics
2
06-28-15 02:21 PM
speedevil
Bicycle Mechanics
9
09-23-13 11:46 PM
Brian7581
Bicycle Mechanics
13
12-17-11 06:00 PM
eggnog
Bicycle Mechanics
22
11-16-11 10:33 PM
chico1st
Bicycle Mechanics
3
02-18-10 09:14 AM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright © 2022 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.