MrCjolsen

I was getting ready to ride to work, and I lightly bumped my rear wheel on wall where I lean it before I leave and "ping" suddenly I had a broken spoke. Thus, I never rode on the wheel after I broke it.

That afternoon (I drove to work) I went to the LBS and got some spokes (I figured I'd need extras in the future. Replacing it was easy. Off with the cassette, take out the old spoke and slide in the new one.

I trued the wheel (got it straigter than before laterally) and did my best to check and adjust the tension.

I have a very slight 1mm or so "hop" but I think that was always there (low-end, stock wheel on a Trek 1000c with over 2k miles on it)

Next day, I rode to work (26 miles RT) and the wheel stayed straight and round (or at least as round as it was)

Questions:

1. How do I adjust the tension without throwing the whole wheel out of true?
2. I read somewhere that I should loosen every spoke 1/2 a turn and then true the wheel. Is that a good or bad idea?
3. Is the "hop" something I can cure with spoke adjustment, or is it my wheel's way of saying "I'm old and tired and cheap to begin with, replace me soon." I'm pretty hard on my rear wheel. I'm a big guy and often commute with a load. My route includes some RR tracks other sorts of unfriendly terrain.
4. I also heard that on an old wheel, I will never get the tension quite right. Is that true?

Thanks.

Al1943

If the hop in the rear wheel is due to a bent rim you need to fix it one way or another. This condition could possibly lead to a bad experience. But the hop could be due to something else like a defective tire or simply a tire bead not properly seated in the rim. You need to fix it. If the rim is slightly bent you may be able to work the bend out using a rubber mallet and blocks of wood.
Anytime you true a wheel try to true it radially as well as laterally, make it round. With the tire and tube removed turn the wheel near a close inanimate object to see if the wheel stay equal distant from the object as it turns. If truing the wheel results in uneven spoke tension this probably means the rim is bent and needs to be repaired or replaced.
Also check for small cracks near the spoke holes, if cracked start looking for a new rim (or wheel).

Al

San Rensho 

I wouldn't worry about 1 mm out of round (or for that matter 1mm lateral out of true). Why do you think your wheel has to be retensioned, are most of the spokes loose? If the wheel is fairly tight and you can true it within 1 mm, I wouldn't fool around with trying to retension. If its an old wheel, and not a great quality wheel, good chance that some of the nipples will not turn, you will strip spokes, etc.

wrench

The spoke broke for a reason. Why?
Most likely causes are overtension of that spoke or undertension of the wheel as a whole. If you replace the spoke, make sure all spokes on the same side are at the same tension. If one has to be too high in order to cure a bent rim, it will go again.
If all the spokes are slack, the elbows will be repeatedly loaded/unloaded every time the wheel goes around and again spokes will break (what happens if you repeatedly bend a paperclip-it breaks). You're a big bloke with over 2000 miles on the wheel. Maybe its time to get a replacement rim and a rebuild. In old wheels that have been bent a bit, you cannot get the tensions even in order for the wheel to be reasonably straight. Once this happens, time for a rebuild.

DannoXYZ 

Overtensioning a spoke will not break it. It will cause the wheel to taco well before tension builds to a level that will break a spoke. You'll also pull the nipple through the rim before you break a spoke from tension. Forced breaks like this will show elongation of the spoke at the failure point. Such as an impact that breaks the spoke. Forced breaks also tend to occur 20-30mm away from the ends.

However, most spoke failures are from fatigue. This occurs over time due to propagation of surface-cracks. When they finally connect all the way through, the spoke breaks. Fatigue failures will have two pieces that fit back together perfeclty, like a jigsaw puzzle.

1. How do I adjust the tension without throwing the whole wheel out of true?

Well, are you sure the overall tension is off? Use a spoke-tension tool to measure each and every spoke first. You can increase tension without affecting true too much by tightening each spoke up the same amount.


2. I read somewhere that I should loosen every spoke 1/2 a turn and then true the wheel. Is that a good or bad idea?

Why would you loosen? Truing is done in pairs by loosening one spoke and tightening the next one. Overall tension remains the same.


3. Is the "hop" something I can cure with spoke adjustment, or is it my wheel's way of saying "I'm old and tired and cheap to begin with, replace me soon." I'm pretty hard on my rear wheel. I'm a big guy and often commute with a load. My route includes some RR tracks other sorts of unfriendly terrain.

Hop is easy to remove. Just tighten spoke-pairs the same amount in that area. Loosen spokes in the areas that's low.


4. I also heard that on an old wheel, I will never get the tension quite right. Is that true?

Well, tension will never be identical, but if you're within +/- 15%, you're fine. Due to the pre-load of the rim, there's aways some spokes that's higher-tension than the others.

shaq-d

1. adjusting tension is easy. grab the spokes and pull them together..known as "stress relieving" (google will tell u more how to do this). do this for all the spokes adjacent to each other, it will untrue the wheel a bit. then tighten it a little bit to get it true and u're good to go.

2. makes no sense to me. but i'm thinking the philosophy behind loosening every spoke is the same as stress relieving.

3. if there's no big issue with ur rim, the hop can be cured with proper truing. spend some more time on it. truing stand or patience will do the trick. remember: always true several spokes at a time in small 1/4-1/2 turns.

sd

dbg

1mm is nothing, especially if you are checking round with the tire mounted (tire /tube anomolies can easily cause 1mm humps on an otherwise true rim). Since you already broke a spoke, it is worth checking for reasonably even tension among all spokes. Drive side will be tighter but if you find wildly variably tension, it's worth removing the tire/tube, loosening all spokes, and doing the interations of re-tension and re-true.

joejack951

Ever try a P9201 for measuring spoke tension? I haven't tried mine yet but I can't see why it wouldn't work.

DannoXYZ 

Heh, heh... that's too funny! Went out and tried it, nope, it's off the scale! Although I need the special $500 calibration-tool to make sure the P9201 is within spec first!

simplify

This totally makes sense to me. I've been having a problem with spoke breakage (at the elbow) in a wheel that was previously ridden undertensioned before I got the bike. Now, even though the spokes are properly tensioned, they still break, and it must be because they already had some fatigue cracks that are working their way through. In fact, I wonder if it might even accelerate their breakage, bringing them up to proper tension when they already had some fatigue-induced cracks. Does that sound possible?

AndrewP

Fix one end of a spoke to an overhead beam, hang a 100 kg weight on the end of it and check the tension with your P9201. You have a calibration tool for the price of a spoke.

joejack951

Hmmm, I might have to figure out what thickness to make those pads so that the gauge will stay within range. Then it would just be a question of does the gauge have enough range for all the different spoke tensions, not to mention figuring out a way to calibrate the gauge. Or I could stop wasting time and effort and bandwidth and just a spoke tension gauge

DannoXYZ 

I wonder how the Kricket tool would work...

joejack951

Funny you mention it, I did a search for information on truing stands yesterday and came across a post where a guy was claiming he used the Kricket to read spoke tension. He said it worked OK but not with the ease of use of a real tensiometer.