Wheelbuilding question....

[ichnusa]

Do bicycle spokes stretch with normal use? Ie: should they be replaced with the nipples when rebuilding a new rim onto a old hub? I know they fatigue and weaken, but do they stretch?

 

thanks

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Edited February 9, 2012 by ichnusa

[David Marshall]

As far as I know they don't. They take strain on the J bend from the natural tension and relaxation caused by the wheel rotation with the riders weight. This is worst on the rear wheel non drive side. Still depending on the value of the hub/rim it is hardly worth re using the old spokes. Also you would need the new rim to have exactly the same diameter as the old one. Idealy your spoke length needs to be correct to 1 mm.

[Dustbin Dog]

Spokes do stretch, thats how you get tension in them. The problem is if they stretch to much the material will yield. Under normal wheel operation the spokes will not yield. Hope this helps, my two cents worth!!

[Johan Bornman]

The answer to your question and the answer to your own explanation of what you really want to know, differs.

 

Spokes stretch elastically about 2mm (for a roadbike or 29er wheel) when properly tensioned.

 

They stretch plastically about 0.5mm during stress relieving, which is the second last phase of the wheelbuilding process.

 

But that doesn't answer your question. You want to know if spokes can be re-used.

 

The pragmatic answer is no. The J-bend ends of inbound and outbound spokes differ in their angle and they are already fatigued. Chaning the angle later on makes for a non-durable wheel. Spokes work perfectly well a second time round if you only transplant the rim without disturbing their original positions, but in a re-build it is very difficult to get them exactly in their previous posiions, hence my caution.

 

Can you re-use nipples? If they are aluminium, no. Heavens, they're hardly good enough for first time use, nevermind recycling.

 

If they are brass and not rounded off or contaminated with dirt, yes. I clean dirty nipples I want to re-use for whatever reason, in an ultrasonic cleaner. That gets rid of the find grit that makes your life hell when tensioning the spokes.

[ichnusa]

thanks... this answers my question. already have new nipples and was planning to keep position of the spokes with masking tape when replacing rim...

[Big H*]

thanks... this answers my question. already have new nipples and was planning to keep position of the spokes with masking tape when replacing rim...

 

I have seen some old nipples in my lifetime that I am sure the owners would like replacing. I wonder if Johan's ultrasonic masjientjie coul be used.

[Johan Bornman]

thanks... this answers my question. already have new nipples and was planning to keep position of the spokes with masking tape when replacing rim...

 

Do it like this:

 

1) Loosen the nipples to almost completely loose on the old wheel.

2) Tape the new rim onto the old one, matching the position of the valve holes.

3) Transfer each spoke to its corresponding position on the new rim and screw on a nipple.

4) Once you've done this 32 times, you can remove the tape, dump the old rim and tension, centre and true the wheel.

 

@Eccentric: yes, the gadget will surely perk them up. I'll do yours for free.