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

Re-spoking questions

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.

Re-spoking questions

Old 11-02-21, 03:24 PM
  #1  
ted_major
Junior Member
Thread Starter
 
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
Re-spoking questions

I'm about to upgrade to a generator lighting system which will obviously necessitate wheelbuilding. This isn't my first set of wheels, so that's not my question. Roger Musson's book got me through the last set of wheels with flying colors, and I'm confident it won't let me down this time as well. However, I'd like to go ahead and order spokes ahead of time to minimize the time my bike is out of commission.

I'm planning on using my existing rims (Alex MD-21), and while I'm rebuilding my front wheel, I figure I'll go ahead and re-spoke the rear wheel, both to replace the straight-gauge spokes with butted ones and to match the front. I know from my last pair (that I used Alex Adventurer 2 rims on) that the manufacturer's published ERD was 4mm less than what I measured, so I don't want to rely on the published ERD for these rims. I also don't want to disassemble my wheels to measure spokes and ERD and then wait a week or more for new spokes and nipples to arrive while my bike sits forlorn and unshod. So that leads to 2 questions:
  1. Is there a reliable (and not too difficult) method to measure ERD on a built-up wheel?
  2. Is there a reliable (and not too difficult) method to measure spoke length on a built-up wheel?
Thanks!
ted_major is offline  
Old 11-02-21, 03:56 PM
  #2  
pdlamb
Senior Member
 
Join Date: Dec 2010
Location: northern Deep South
Posts: 7,908

Bikes: Fuji Touring, Novara Randonee

Mentioned: 33 Post(s)
Tagged: 0 Thread(s)
Quoted: 2090 Post(s)
Liked 1,337 Times in 848 Posts
For (2), take a spoke off and measure it. Better yet, on a rear wheel, take one from each side off and measure it. Make sure you replace the first one and re-true before messing things up royally by taking two off at once.

I'd suggest getting new rims, while you're at it. Compared to the cost of a dyno hub, it doesn't add much, but it'll cut your down time way down.
pdlamb is offline  
Old 11-02-21, 08:54 PM
  #3  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 16,744

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Srewart 650B ATB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3629 Post(s)
Liked 2,576 Times in 1,615 Posts
With skill and experience a lot of "uncommon" measuring of stuff can be spot on. But lacking that pull a spoke or two and reverse math the ERD. Andy
__________________
AndrewRStewart
Andrew R Stewart is offline  
Likes For Andrew R Stewart:
Old 11-02-21, 11:00 PM
  #4  
Russ Roth
Senior Member
 
Join Date: Dec 2019
Location: South Shore of Long Island
Posts: 2,128

Bikes: 2010 Carrera Volans, 2015 C-Dale Trail 2sl, 2017 Raleigh Rush Hour, 2017 Blue Proseccio, 1992 Giant Perigee, 80s Gitane Rallye Tandem

Mentioned: 9 Post(s)
Tagged: 0 Thread(s)
Quoted: 807 Post(s)
Liked 645 Times in 487 Posts
Isn't hard if you have one of the sewing tape measures, they come in metric. Take a longish piece of cardboard from one of those amazon boxes you probably have lying about, cut out an arch from it so it can sit over the hub and axle, mark the inside edges of the rim on the cardboard (this is easiest if the tire is off and the cardboard edge can sit right on the rim) from two spots directly opposite each other. Measure the distance between the marks, and add 3-4mm to the length to cover the thickness of the rim and get the threads into the spoke nipples.
Russ Roth is offline  
Old 11-03-21, 05:59 PM
  #5  
ted_major
Junior Member
Thread Starter
 
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 pdlamb View Post
I'd suggest getting new rims, while you're at it. Compared to the cost of a dyno hub, it doesn't add much, but it'll cut your down time way down.
I've considered that option, but rim availability seems pretty spotty these days. Any recommendations for an available, reasonably-priced 32-hole 650b disc rim for 42-47mm tires?

Using new rims would also tempt me to further expand the scope of the project: once I'm buying new rims, I might as well replace the rear hub, too...
ted_major is offline  
Old 11-04-21, 06:36 AM
  #6  
Dan Burkhart 
Senior member
 
Dan Burkhart's Avatar
 
Join Date: Oct 2004
Location: Oakville Ontario
Posts: 7,908
Mentioned: 23 Post(s)
Tagged: 0 Thread(s)
Quoted: 843 Post(s)
Liked 461 Times in 262 Posts
Originally Posted by ted_major View Post
I've considered that option, but rim availability seems pretty spotty these days. Any recommendations for an available, reasonably-priced 32-hole 650b disc rim for 42-47mm tires?

Using new rims would also tempt me to further expand the scope of the project: once I'm buying new rims, I might as well replace the rear hub, too...
It depends what you consider reasonably priced, but the Velocity Cliffhanger is available (just brought in 2 of them in that size) and you can just go with a non machined brake track and call it a disc rim.https://www.velocityusa.com/product/...liffhanger-584
Dan Burkhart is offline  
Old 11-04-21, 07:48 AM
  #7  
Moe Zhoost
Half way there
 
Moe Zhoost's Avatar
 
Join Date: Sep 2015
Location: North Carolina
Posts: 2,792

Bikes: Many, and the list changes frequently

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 921 Post(s)
Liked 765 Times in 457 Posts
Personally, I would skip rebuilding the back wheel. The marginal gains are just not worth the effort. OTOH, if you just want the practice or if you have some damaged spokes, go for it.

What hub are you planning to use? I've used Shimano, Sturmey, and Shutter Precision (which I like the best). SON was a bit too expensive for my budget.
Moe Zhoost is online now  
Old 11-04-21, 07:53 AM
  #8  
cyccommute 
Mad bike riding scientist
 
cyccommute's Avatar
 
Join Date: Nov 2004
Location: Denver, CO
Posts: 25,706

Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones

Mentioned: 138 Post(s)
Tagged: 1 Thread(s)
Quoted: 5149 Post(s)
Liked 2,694 Times in 1,595 Posts
Originally Posted by ted_major View Post
I'm planning on using my existing rims (Alex MD-21), and while I'm rebuilding my front wheel, I figure I'll go ahead and re-spoke the rear wheel, both to replace the straight-gauge spokes with butted ones and to match the front. I know from my last pair (that I used Alex Adventurer 2 rims on) that the manufacturer's published ERD was 4mm less than what I measured, so I don't want to rely on the published ERD for these rims.
Iíve built a lot of wheels and seldom do I measure the ERD myself. The published ones are good enough or wonít make enough of a difference to matter. Additionally, if I were measuring the ERD, I would suspect my own measurement over that of the manufacturer. They measure ERD all the time. I would trust that they know what they are doing because they do it far more often than I do.

The other thing to consider is how much of a difference will it really make? Using the ERD for a 622mm Alex MD-21 of 608mm and an ERD that is 4mm less (604mm), Prowheel Builderís spoke calculator returns lengths of 298mm and 296mm, respectively, for the two ERDs. Often Iíve had to compromise on spoke length of about the difference due to availability. Iíd probably err on the long side rather than the short one, however.

If you really have to let your OCD kick in, you could measure from the j-bent to the outside of the rim, then measure from the spoke end to the outside of the rim and subtract the difference. Do it more than once (or even twice or even 3 times) and average the results. But thatís a lot of work and is likely to have a whole lot of variance. Probably more than just going with the manufacturerís ERD
__________________
Stuart Black
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Days of Wineless Roads. Bed and Breakfasting along the KATY
Twisting Down the Alley. Misadventures in tornado alley.
cyccommute is online now  
Old 11-04-21, 07:17 PM
  #9  
ted_major
Junior Member
Thread Starter
 
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 Moe Zhoost View Post
Personally, I would skip rebuilding the back wheel. The marginal gains are just not worth the effort. OTOH, if you just want the practice or if you have some damaged spokes, go for it.

What hub are you planning to use? I've used Shimano, Sturmey, and Shutter Precision (which I like the best). SON was a bit too expensive for my budget.
I get that a probably wonít be able to tell any difference on the rear wheel, but I have a feeling Iím not going to like the look of shiny new butted spokes on the front and black straight gauge on the back. I enjoyed building my first set of wheels, so Iíll probably do it as much for skill development as anything else.

As far as hubs, Iíve got a Kasai FS on the way. Iím a little leery of components that need to be shipped overseas for service, even if that service isnít likely to happen soon. The serviceability aspect was enough for me to finally give it a shot. (I canít quite bring myself to shell out for a SON either.)
ted_major is offline  
Old 11-04-21, 07:26 PM
  #10  
ted_major
Junior Member
Thread Starter
 
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 cyccommute View Post

The other thing to consider is how much of a difference will it really make? Using the ERD for a 622mm Alex MD-21 of 608mm and an ERD that is 4mm less (604mm), Prowheel Builderís spoke calculator returns lengths of 298mm and 296mm, respectively, for the two ERDs. Often Iíve had to compromise on spoke length of about the difference due to availability. Iíd probably err on the long side rather than the short one, however.
You make a good point, and I have wondered how much difference 4mm makes in the end. As a baby wheel builder, Iím still just following directions.

Musson said not to trust the mfr and to take my own measurements, so thatís what I did and it worked. I figured Iíd do the same thing this go Ďround, but using the mfr specs would be easier, and youíre absolutely right that trying to measure a built rim by adding and subtracting several measurements would probably be less reliable than the published numbers. Tolerance stacking in action!
ted_major is offline  
Old 11-07-21, 10:18 AM
  #11  
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
Tolerance stacking or uncertainty stacking, exactly. Going to be really hard to come up with ERD or spoke length measurements by measuring a built wheel.

I always measure ERD myself. Errors of 2-3 mm are not uncommon. On the DTs in particular they may be using the proprietary nips (Squorx) as the basis of measurement.

you can make up your own ERD measuring tools as shown. Thread nips onto 2 spokes and cut them at exactly 250 mm. Drop them into 2 rim holes 180 deg. apart. Measure the gap as shown and add that to 500.

/markp


mpetry912 is offline  
Old 11-08-21, 10:54 AM
  #12  
ted_major
Junior Member
Thread Starter
 
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 pdlamb View Post
I'd suggest getting new rims, while you're at it. Compared to the cost of a dyno hub, it doesn't add much, but it'll cut your down time way down.
In the end, I've decided that pdlamb has some of the best advice in the thread. As my wife pointed out, "Go ahead and try that if you want, but in the end it probably won't work out right and you'll just end up ordering new rims anyway, so you might as well just get them now and save yourself time and trouble." So now I've got a pair of WTB KOM i23 rims and a Bitex MTR 12 rear hub on the way. Once they're here, I'll confirm measurements and order spokes and nipples (14/15 ga butted).

As far as my original question goes, I found that Musson describes how to measure the ERD of a built rim in his book. He says to measure the OD of the rim by rolling 1 revolution on a flat surface, measuring that distance, and dividing by pi. Next, measure the distance from the rim to the top of a nipple. Subtract twice that distance and then subtract another 2mm to get to the bottom of the slot in the nipple.

I came out with an answer that was off from the published ERD by 2.8mm. Maybe close enough, but I think I'll just make this easier on myself.

Originally Posted by mpetry912 View Post
Tolerance stacking or uncertainty stacking, exactly. Going to be really hard to come up with ERD or spoke length measurements by measuring a built wheel.

I always measure ERD myself. Errors of 2-3 mm are not uncommon. On the DTs in particular they may be using the proprietary nips (Squorx) as the basis of measurement.

you can make up your own ERD measuring tools as shown. Thread nips onto 2 spokes and cut them at exactly 250 mm. Drop them into 2 rim holes 180 deg. apart. Measure the gap as shown and add that to 500.

/markp
Didn't take too much fooling around with measuring tools to destroy what little confidence I had in my own measuring ability. I've got a pair of spokes I prepared in similar fashion from the last wheels I built that I'll use when my rims come in.
ted_major is offline  

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.