Wheel truing gone wrong
#101
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My truing stand checks both sides of the wheel simultaneously so I don't have to flip it to get proper dish - one of the reasons I got it - saves me from having to get another tool.
#102
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Depending oh how they support the axle, they're vulnerable to errors introduced by a bent axle, or wear or distortion where the axle meets the stand. Often you can see these errors by positioning the wheel but not tightening it in place, then using a cone wrench to rotate the axle. Errors of the type I described will move the rim side to side, throwing the dish readings off.
Then, depending on the construction of the stand, there's always the risk of the centering calibration going off. The Park TS-2 stands are notorious for this problem.
However, there's no need to buy a dishing gauge, since a very accurate one can be made at zero cost, whenever needed, using a table, 3 soup cans, and a stack of coins.
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Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#103
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Truing stands are unreliable for checking dish because they're subject to various errors.
Depending oh how they support the axle, they're vulnerable to errors introduced by a bent axle, or wear or distortion where the axle meets the stand. Often you can see these errors by positioning the wheel but not tightening it in place, then using a cone wrench to rotate the axle. Errors of the type I described will move the rim side to side, throwing the dish readings off.
Then, depending on the construction of the stand, there's always the risk of the centering calibration going off. The Park TS-2 stands are notorious for this problem.
However, there's no need to buy a dishing gauge, since a very accurate one can be made at zero cost, whenever needed, using a table, 3 soup cans, and a stack of coins.
Depending oh how they support the axle, they're vulnerable to errors introduced by a bent axle, or wear or distortion where the axle meets the stand. Often you can see these errors by positioning the wheel but not tightening it in place, then using a cone wrench to rotate the axle. Errors of the type I described will move the rim side to side, throwing the dish readings off.
Then, depending on the construction of the stand, there's always the risk of the centering calibration going off. The Park TS-2 stands are notorious for this problem.
However, there's no need to buy a dishing gauge, since a very accurate one can be made at zero cost, whenever needed, using a table, 3 soup cans, and a stack of coins.
#104
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I agree completely. But (as I'm sure you know) you can center the rim on a TS-2 or other any descent truing stand by reversing the wheel on the stand multiple times and adjusting the spokes until the rim is centered regardless of which way you mount the wheel to the stand. This can be done by using only one caliper arm whether you have one or two. With practice this can be done quickly.
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Just because I'm tired of arguing, doesn't mean you're right.
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FB
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
#105
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Depending oh how they support the axle, they're vulnerable to errors introduced by a bent axle, or wear or distortion where the axle meets the stand. Often you can see these errors by positioning the wheel but not tightening it in place, then using a cone wrench to rotate the axle. Errors of the type I described will move the rim side to side, throwing the dish readings off. Then, depending on the construction of the stand, there's always the risk of the centering calibration going off. The Park TS-2 stands are notorious for this problem.
I have a dish tool as well but generally only use it to check the dish after the wheel comes off the stand just as confirmation that all is well. If the stand goes out of center for dish - I'll simply build a wooden disc and put a solid axle through it and then use that to re-center everything. As with any calibrated tool - the calibration does need checked periodically and possibly adjusted.
Anything that can touch the rim and then be adjusted to reach the axle nut reliably will work .
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The axle on my Trek is actually slightly bent [not sure how that happened] but I trued it up and checked dish and it was fine. It'll never be perfect but I doubt I could get it perfect with a bent axle even if I used a dishing tool religiously.
I was able to see the very slight bend in the axle as I rotated the wheel on the stand - this was likely the largest reason my wheel was out of true - I don't think that the spokes were really improperly tensioned but instead that the bent axle threw the whole wheel off giving me a wobble.
I was able to clean it up with the stand and get it to rideable condition but, that said, I'm looking at a couple of IGH hubs to build a wheel for this bike on . 11-speed IGH sounds like fun .
#107
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I agree completely. But (as I'm sure you know) you can center the rim on a TS-2 or other any descent truing stand by reversing the wheel on the stand multiple times and adjusting the spokes until the rim is centered regardless of which way you mount the wheel to the stand. This can be done by using only one caliper arm whether you have one or two. With practice this can be done quickly.
One thing that hasn't been mentioned is ensuring the bearings in the axle are in fact in good condition and properly adjusted. It's also a reason why I use the QR in the truing stand to tighten the bearings to their riding tension.
#108
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I don't know so much about wheelbuilding, being rather a novice, but was taught that the purpose of the tension gauge was to make sure that the spokes are tensioned enough (that is, each spoke has more than a minimum amount of tension), and to attempt to get approximately the same tension on each spoke around the wheel. Yes, you can do this by sound ... but it's much harder to teach/learn "ping" not "ding" than it is to say "measure each spoke, take the average, if the average is >=20 and no spoke is out of the range 20+-2, and it's round, dished, and true, then you're done."
#109
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I think a lot of the analogies where measuring creates a better product are not on point It really is an it depends on what you are doing.
My father tuned pianos with a tuning fork and his ear. His pianos were in tune. I learned to tune a piano from him. Now most all piano tuners tune from digital tuning machine which shows the frequency. It is faster but no better if you trained your ear. So, in this case "measuring" helps.
I played violin. You tuned the A string to a fork or known pitch at 440hz and used your ear to tune the other strings. Most players still tune all but the A using their ear. Perfect 5ths are easy to hear and you can check using harmonics. It isn't going to be more in tune by checking the frequency of the other strings using a machine. However, I understand some beginner violinists do use a digital tuner. I think they are not doing their ears a favor. I also see more and more guitar players tuning with digital tuners. I still only tune one string by frequency and then use the ear for the rest. I am not going to be more in tune by checking my work as my ear and experience gets me where I need to be quickly.
My father tuned pianos with a tuning fork and his ear. His pianos were in tune. I learned to tune a piano from him. Now most all piano tuners tune from digital tuning machine which shows the frequency. It is faster but no better if you trained your ear. So, in this case "measuring" helps.
I played violin. You tuned the A string to a fork or known pitch at 440hz and used your ear to tune the other strings. Most players still tune all but the A using their ear. Perfect 5ths are easy to hear and you can check using harmonics. It isn't going to be more in tune by checking the frequency of the other strings using a machine. However, I understand some beginner violinists do use a digital tuner. I think they are not doing their ears a favor. I also see more and more guitar players tuning with digital tuners. I still only tune one string by frequency and then use the ear for the rest. I am not going to be more in tune by checking my work as my ear and experience gets me where I need to be quickly.
Meanwhile every wheel out there has a different combination of spoke length, gage, lacing and rim properties which would create a different target frequency for each combination and little if any distinct harmonic, and a mechanic let alone a home mechanic generally puts tone recognition pretty low down the list on his resume (not because it's a bad thing but mechanics have a huge list of priorities that come before tone) unlike a specialist musical instrument tuner.
Though for factory production of hundreds of identical new wheels there is a company that uses a digital tone meter on it's building machine, I think it's Easton but their site is down now so I can't check.
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Old methods work, new methods have been developed because the old methods have some weaknesses, pros & cons and all that.
If you use a gage, make sure you treat it well and give it some light oil like triflow on a regular basis.
I use to work in a shop where I would hand true about 3000 new machine built wheels per year, from various makes and models. Tension gages were preferred to fiddling with old timey methods for both consistency and speed. On a good factory wheel this would take about 3-5 minutes, on a bad one(with a slightly warped rim and crazy off tension) maybe 15.
The basic process when using a gage was: stress the spokes, check dish, test a few spokes in a row for tension to get a basic tension starting point, if way off target give every spoke a quarter, half, or full turn(depending on the starting tension and dish. Treat every spoke on one side with the exact same amount of turns or you may screw the radial hop. Do not stop half way around to check tension, answer the phone, fight off a bee, or anything else.) note any spokes that feel like outliers double check them with the gage and load balance as necessary,
Stress again, check a few more spokes,
When tension is close, move on to truing, and true with balanced turns to avoid throwing off the radial or the tension. eg, if the spoke in the center of the wobble is on your right and needs to be about a half turn looser then take up the slack with 1/4-1/2 turn tighter on both adjacent spokes on your left. Small adjustments of about 1/4 total turns and less generally don't need balancing.
Stress again, check dish and true again, make fine adjustments, rinse&repeat as needed, ending with stress, check, done.
There was a direct correlation between turns and tension readings something like one full turn on each spoke would swing from 18-22 on the park gage, I don't recall the exact number as I haven't done it in about 2 years, it was not quite linear though, more turns were needed to adjust one point at very low tension than were needed at very high tension.
If you use a gage, make sure you treat it well and give it some light oil like triflow on a regular basis.
I use to work in a shop where I would hand true about 3000 new machine built wheels per year, from various makes and models. Tension gages were preferred to fiddling with old timey methods for both consistency and speed. On a good factory wheel this would take about 3-5 minutes, on a bad one(with a slightly warped rim and crazy off tension) maybe 15.
The basic process when using a gage was: stress the spokes, check dish, test a few spokes in a row for tension to get a basic tension starting point, if way off target give every spoke a quarter, half, or full turn(depending on the starting tension and dish. Treat every spoke on one side with the exact same amount of turns or you may screw the radial hop. Do not stop half way around to check tension, answer the phone, fight off a bee, or anything else.) note any spokes that feel like outliers double check them with the gage and load balance as necessary,
Stress again, check a few more spokes,
When tension is close, move on to truing, and true with balanced turns to avoid throwing off the radial or the tension. eg, if the spoke in the center of the wobble is on your right and needs to be about a half turn looser then take up the slack with 1/4-1/2 turn tighter on both adjacent spokes on your left. Small adjustments of about 1/4 total turns and less generally don't need balancing.
Stress again, check dish and true again, make fine adjustments, rinse&repeat as needed, ending with stress, check, done.
There was a direct correlation between turns and tension readings something like one full turn on each spoke would swing from 18-22 on the park gage, I don't recall the exact number as I haven't done it in about 2 years, it was not quite linear though, more turns were needed to adjust one point at very low tension than were needed at very high tension.
Last edited by capsicum; 06-19-14 at 07:04 PM. Reason: clarification