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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.

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Old 08-31-08, 02:04 PM   #1
HopliteGrad
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How True Is Out of True?

As in, how much taco can I have in my wheel before I should worry? Right now my front and back wheels on my monstrous steel hybrid commuter each wobble perhaps 1-2 mm, enough to brush the brake pads ever so slightly if I don't adjust them periodically, say once a month. They are not perceptibly out of round yet.

I'm in a context where having them retrued is a stretch and getting new wheels is a BIG stretch. (unless super cheap, true wheels are available somehow).

I have a spoke wrench and got them down to 1-2mm out of true from what they were before, perhaps 5-8mm out of true. Then I read stuff about spoke tensioning and figured I shouldn't monkey too much.

Hop
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Old 08-31-08, 02:52 PM   #2
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That seems fine, but it would bug the heck out of me.

I always thought a taco was when a wheel was bent to the point of no return, such as so much bending that the rim cracks so from that definition any taco is bad.

Yea, you might not want to do more than 1 or two revolutions of the nipple when truing your own wheels unless you really want to mess around with spoke tension. It is better, I believe, to adjust one or two more spokes if it means you only have to turn each nipple a eighth or a quarter of a turn.

Also, remember that you are just doing lateral true and while fixing that, you almost in all likelihood messed around with the radial true, i.e. your wheel is no longer a perfect circle though I do believe most people on here would place lateral true in greater importance that radial true.
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Old 08-31-08, 02:54 PM   #3
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1-2mm is nothing but really you should beable to dial them in so there is no run out.

The other day i hit a curb avoiding a truck that went right on red infront of me. Killed my rear rim on the wheels i just finished building. It bent the side walls down on each side and tacoed the rim maybe 10mm out of round. I got it home and got out my hammer anvil and a file. I went to work and now the rim is nice and true. Luckly i don't use rim brakes on my commuter or i would be looking for a new rim.

good luck and just sick with getting it true.
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Old 08-31-08, 03:05 PM   #4
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It bent the side walls down on each side and tacoed the rim maybe 10mm out of round.
I guess I got the definition of taco wrong. I always thought a tacoed wheel looks like a taco.
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Old 08-31-08, 03:11 PM   #5
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1 mm is OK but if I see 2mm I adjust the spots that are out.

A good check for even tension is to tap the spokes with a plastic screwdriver handle. All the spokes on a side should sound close to the same and give a musical tone. If they just give a dead sounding thump then they are far too loose.

The front on a rim brake wheel should sound the same side to side. A few "keys" difference isn't a big deal but if you hear a full octave difference it's time to retension and retrue.

Here's a freeware piano note generator to get an idea of what I'm talking about....

http://www.freedownloadscenter.com/M...nic_Piano.html
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Old 08-31-08, 04:13 PM   #6
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I guess I got the definition of taco wrong. I always thought a tacoed wheel looks like a taco.
Me too. I think you're more-or-less right. Often, a person will embrace a word they've heard and assign their own definition. To me, "tacoed" means radically bent, not just mildly to wildly out-of-true or having some rim damage.
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Old 08-31-08, 04:17 PM   #7
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I guess I got the definition of taco wrong. I always thought a tacoed wheel looks like a taco.
I think this is nearly everyone's definition of taco. Otherwise it's known as "out of true".
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Old 08-31-08, 04:17 PM   #8
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A good check for even tension is to tap the spokes with a plastic screwdriver handle. All the spokes on a side should sound close to the same and give a musical tone. If they just give a dead sounding thump then they are far too loose.

The front on a rim brake wheel should sound the same side to side. A few "keys" difference isn't a big deal but if you hear a full octave difference it's time to retension and retrue.

Here's a freeware piano note generator to get an idea of what I'm talking about....

http://www.freedownloadscenter.com/M...nic_Piano.html
A good check is to buy a tensionmeter.
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Old 08-31-08, 05:02 PM   #9
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A good check is to buy a tensionmeter.
This is the kind of thing I'm trying to piece together. How important is it to have a tensionmeter for truing up wheels? (tensiometer?) I don't really have any plans or need at all to teach myself to handbuild wheels-- oh, the joys of industrial societies with segmentations of production, right?

So is a tensionmeter recommended for basic maintenance/retruing or for handbuilding/relacing a wheel?
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Old 08-31-08, 05:24 PM   #10
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It's all about tension, without even tension the wheel will never work. For basic maintenance truing you can get away without one, but for wheel building and major overhaul it is vital.
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Old 08-31-08, 05:52 PM   #11
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If you have a run out of 1-2mm and you are hitting the brake pads, you must like your brakes super tight.
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Old 08-31-08, 06:15 PM   #12
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Often, a person will embrace a word they've heard and assign their own definition.
I also make up words for cycl... um.. help....?!?!?! I accidentally pressed something and now my screen is sideways... as I am typing this, the letters are going up.... I think it was ALT+something...
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Old 08-31-08, 06:29 PM   #13
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Ok, problem solved apparently CTRL+ALT+any cursor button does funny things.

I would not say you would need a tensionmeter unless your wheel is so off that you cannot ride any faster than you can walk - that would require some major work and patience. With that being said, that happened to me (car whacked me) and I just found it more convenient to get it fixed in a shop.
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Old 08-31-08, 06:40 PM   #14
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If you've ever seen a truly taco'ed wheel it's far more than just out of true. WHen a wheel tacos it actually snaps past the spokes on one side so the spokes go past vertical and no longer support the rim properly with one side in opposition to the other. If you don't actually snap the rim past vertical on the one series of spokes I'd suggest that it's not taco'ed and is just "out of true".

http://www.instructables.com/files/d...7HZ.MEDIUM.jpg

Now THAT is a taco. Note how the spokes from one side are no longer under tension and are actually sticking up out of the rim? When the guy stomps it back down it'll drive those loose spokes back over center and they'll then have their tension restored. It won't be pretty but if it doesn't explode it'll get the guy home.

Tensionometer is a nice thing to have but you don't NEED one to build or true up wheels. A lot of us do it by ear through setting up the spokes to even musical notes of the desired value. I've done a good 12 pairs over the years and only had minor tuning issues with one road wheel and no more than the issues I'd expect with my mountain bike wheels. All without a tensionometer. I'm sure you'll find a lot of wheelbuilders that built hundreds of wheels in the past without them as well.
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Old 08-31-08, 06:43 PM   #15
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If you have a run out of 1-2mm and you are hitting the brake pads, you must like your brakes super tight.
That's entirely possible; I don't have any frame of reference for what is a small or large brake gap. I'm guessing that 1-2mm gap between rim and brake sounds pretty small, but I suppose I'm happy enough with it. Ignorance is bliss?

What is a more usual or customary gap size?

Thanks!
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Old 08-31-08, 06:47 PM   #16
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I prefer a short free movement in the brake levers so I typically set the clearance to 1mm. I guess I assumed that everyone does it this way.
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Old 08-31-08, 07:15 PM   #17
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I prefer a short free movement in the brake levers so I typically set the clearance to 1mm. I guess I assumed that everyone does it this way.

I do it the same way, but I'm a relative newb.
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Old 08-31-08, 07:19 PM   #18
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Yes it is. If that's how you're using the term, then indeed my wheel is not tacoed, simply out of true. So what I'm hearing is that if I can play a complete song on my spokes, that's not good. But 1-2mm out of true is more a nuisance than a real issue. Of course, I'll continue to play with the spokes and try to reduce the untrue-ness while keeping spoke pitch as uniform as possible.
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Old 08-31-08, 08:03 PM   #19
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But 1-2mm out of true is more a nuisance than a real issue. Of course, I'll continue to play with the spokes and try to reduce the untrue-ness while keeping spoke pitch as uniform as possible.
If you insist on trying to get that last mm out, make any adjustments very very small (say 1/8 of a turn at a time, at the belly of the "bend").
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Old 09-01-08, 09:04 AM   #20
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I guess I got the definition of taco wrong. I always thought a tacoed wheel looks like a taco.
Actually, taco isn't a very accurate descriptive word. "Pringle" would be a better word for describing the double fold shape the wheel takes when the rim goes over center.
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Old 09-01-08, 09:05 AM   #21
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I prefer a short free movement in the brake levers so I typically set the clearance to 1mm. I guess I assumed that everyone does it this way.
So do I.

I aim at 0.2 mm, both sideways and circular when truing wheels. That can be achieved with no special gauges. A good eye, a good spoke wrench, some experience and a lot of patience is all one needs.

A perfectly built wheel is ever so important when it comes to braking smoothly (and safely).
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Old 09-01-08, 12:37 PM   #22
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Actually, taco isn't a very accurate descriptive word. "Pringle" would be a better word for describing the double fold shape the wheel takes when the rim goes over center.
I was thinking non-extremum stationary point figure, but pringle is a much catchier handle, yup.
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Old 09-01-08, 12:43 PM   #23
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I can and have built wheels without a tension-meter... now that I have one if just confirms that my hands know what they have been doing and that my hearing is just fine.

Wheels should be no more than .5 mm out of true and I prefer even closer tolerances.
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Old 09-01-08, 01:28 PM   #24
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Ok, problem solved apparently CTRL+ALT+any cursor button does funny things.

I would not say you would need a tensionmeter unless your wheel is so off that you cannot ride any faster than you can walk - that would require some major work and patience. With that being said, that happened to me (car whacked me) and I just found it more convenient to get it fixed in a shop.
And you can only do this when logged in to!
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Old 09-01-08, 02:07 PM   #25
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Tensionometer is a nice thing to have but you don't NEED one to build or true up wheels. A lot of us do it by ear through setting up the spokes to even musical notes of the desired value. I've done a good 12 pairs over the years and only had minor tuning issues with one road wheel and no more than the issues I'd expect with my mountain bike wheels. All without a tensionometer. I'm sure you'll find a lot of wheelbuilders that built hundreds of wheels in the past without them as well.
Sorry, but I like to resist this idea.

No professional wheelbuilder will be without a tensionmeter for ANY of their wheelbuilds. For home hack mechanics yeah, you might be able to get away without having one but if you're buliding up a powertap to a reynolds dv46c rim and sapim cx-rays and charginig someone for it.

You better have a tensionmeter.

This isn't a joke.

If you can be as accurate as the DT swiss tensionmeter when doing your musical notes then you have got to be a prodigy this world has never seen. Especially considering the amount of different spokes out there you'd have to learn all the tones for. Double butted, single butted, straight gauge, different length spokes.

I like the "let's shun progress" and the "people were doing fine before without them" attitudes but it is seriously misplaced for wheelbuilding.
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