Bicycle Mechanics - Wheelbuilding spoke question

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.




View Full Version : Wheelbuilding spoke question


Mudu93
01-18-08, 08:09 PM
I have a set of Mavic MA3 with 105 hubs 32 spoke count as a spare wheelset that I purchased used. I have however broken a spoke and have decided that I should use this opportunity to learn how to put a wheel together. There is a local guy willing to walk me through it and help me if I get in over my head, but I need to get the spokes and nipples. What size spokes do I need? Should I go with brass nipples? Give a brother some advise please. Thanks


Cynikal
01-18-08, 08:14 PM
I would read this. http://sheldonbrown.com/wheelbuild.html

It should be all you need to know.

Retro Grouch
01-18-08, 09:13 PM
The easiest way to determine what spoke length that you need is to remove a good spoke from the wheel and measure it.

Aluminum nipples are lighter in weight and look cooler because they come in different colors. Brass nipples are a lot more durable.


operator
01-18-08, 09:14 PM
Don't bother with AL nipples.

wroomwroomoops
01-18-08, 09:18 PM
Just for the record, brass nipples are usually plated with nickel, so they are NOT yellow.

Mudu93
01-19-08, 10:14 AM
The easiest way to determine what spoke length that you need is to remove a good spoke from the wheel and measure it.

That make entirely too much sense. Somebody call Bill Engvall. I need a stupid sign. Thanks for the help all.:D

dvs cycles
01-19-08, 10:30 AM
That make entirely too much sense. Somebody call Bill Engvall. I need a stupid sign. Thanks for the help all.:D This won't be 100% accurate because spokes stetch some.

HillRider
01-19-08, 11:10 AM
This won't be 100% accurate because spokes stetch some.
That's an interesting comment. Do they really? Are spokes stressed beyond their elastic limit when tensioned? If not, they don't "stretch" permanantly and will return to their original length when tension is removed.

Dan Burkhart
01-19-08, 11:51 AM
That's an interesting comment. Do they really? Are spokes stressed beyond their elastic limit when tensioned? If not, they don't "stretch" permanantly and will return to their original length when tension is removed.
If you post this comment on RBT, you will get several contradictory "expert" opinions and start a war in the process.

dvs cycles
01-19-08, 12:31 PM
If you post this comment on RBT, you will get several contradictory "expert" opinions and start a war in the process.Take one apart and try it your self. They won't all measure quite the same. Some of the elongation is fron the hooks taking a spokeline.
I've done it. So that must make me an expert?:rolleyes:

graybeard
01-19-08, 01:10 PM
DT Swiss and Wheelsmith both have spoke calculators in their websites I think. they are both very popular spoke manufacturers.

Retro Grouch
01-19-08, 01:29 PM
This won't be 100% accurate because spokes stetch some.

I guess that's the difference between an engineer and a mechanic. Measureing a single spoke, or one from each side, is what I've done countless times when replacing spokes or even rebuilding an entire wheel. It's never failed me yet. Sometimes close enough is close enough.

wroomwroomoops
01-19-08, 01:43 PM
I guess that's the difference between an engineer and a mechanic. Measureing a single spoke, or one from each side, is what I've done countless times when replacing spokes or even rebuilding an entire wheel. It's never failed me yet. Sometimes close enough is close enough.

Uhhhhh... the difference between an engineer and a scientist, maybe? I am an engineer, and my whole engineering life has been spent in making useful approximations.

geo8rge
01-19-08, 02:13 PM
If the spokes are a bit too long, feel free to grind off the ends with a dremel w diamond cutting wheel. If they are too short you are screwed. If they are way too long you are screwed too.

HillRider
01-19-08, 02:43 PM
Take one apart and try it your self. They won't all measure quite the same. Some of the elongation is from the hooks taking a spokeline.
I've done it. So that must make me an expert?:rolleyes:
Having spokes elongate from stress relieving, which does plastically deform the hook, is a reasonable explanation and such spokes will measure slightly longer than their initial spec.

However, the straight section of the spoke does not elongate permanently under tension unless it has been badly over tensioned. Also spokes do not elongate over time once tensioned.

wroomwroomoops
01-19-08, 03:12 PM
However, the straight section of the spoke does not elongate permanently under tension unless it has been badly over tensioned. Also spokes do not elongate over time once tensioned.

+1

dvs cycles
01-19-08, 06:03 PM
Having spokes elongate from stress relieving, which does plastically deform the hook, is a reasonable explanation and such spokes will measure slightly longer than their initial spec.

However, the straight section of the spoke does not elongate permanently under tension unless it has been badly over tensioned. Also spokes do not elongate over time once tensioned.But either way it is still longer and using a new spoke that length could be a problem such as bottoming the threads out or sticking past the nipple. And I said it could be a problem. Just like to cover all bases.:)

dvs cycles
01-19-08, 06:07 PM
I guess that's the difference between an engineer and a mechanic. Measureing a single spoke, or one from each side, is what I've done countless times when replacing spokes or even rebuilding an entire wheel. It's never failed me yet. Sometimes close enough is close enough.
Please no name calling here!:eek: I am NOT an engineer.:rolleyes: I'm just a retired electrcian with a 30 year old hobby of building and racing bikes. I repeat I AM NOT AN ENgineer.:D
Like we say in construction, measure twice cut once.;)

wroomwroomoops
01-19-08, 07:20 PM
I am a graduate electrical engineer, and am very proud of it. My role models are Nicola Tesla, Charles Proteus Steinmetz and Michael Faraday. Engineers are not stupid, they always keep an eye on the order of magnitude of things. I used to have a romantic interest who is a doctors of science in chemistry - who didn't know the ballpark of the wavelenght of visible light. An electrical engineer would never make such a goof.

HillRider
01-19-08, 07:56 PM
Like we say in construction, measure twice cut once.;)
Well, if the spoke really is longer than it started out, measuring twice will give you the wrong answer twice. ;)

Seriously, if inspection of a removed but still intact spoke shows the bend at the hook is no longer 90° then a correction for the elongation can be made rather easily.

graybeard
01-19-08, 09:10 PM
get along children

Retro Grouch
01-20-08, 05:34 AM
Engineers are not stupid, they always keep an eye on the order of magnitude of things.

That's exactly my point. Spokes have to be the right length within about plus or minus 1 mm. Measureing more precisely than that, or maybe measuring and averaging a whole wheel's worth of spokes may be more accurate but it's not necessary.

tzracer
01-20-08, 06:24 AM
Uhhhhh... the difference between an engineer and a scientist, maybe? I am an engineer, and my whole engineering life has been spent in making useful approximations.

Scientists (I am a physicist) make approximations (models are approximations-ideal gas) when appropriate - examples - see Born Approximation and Perturbation Theory. There are many others, especially in any fields that make use of statistics (Quantum Mechanics and Statistical Mechanics for example).

Oh and I do know the wavelengths of visible light :)

Dan Burkhart
01-20-08, 08:06 AM
Please no name calling here!:eek: I am NOT an engineer.:rolleyes: I'm just a retired electrcian with a 30 year old hobby of building and racing bikes. I repeat I AM NOT AN ENgineer.:D
Like we say in construction, measure twice cut once.;)
I cut it twice and it was still too short:D I'll just go get the board stretcher.