How tight should spokes be?
I'm a drummer and truing wheels is like tuning drums. When I tune drums, I tend to get all the tension rods (the drum equivalent to spoke nipples) to the same tension before actually tuning the drum - this means that once the tension is equal, I can just add more tension to each tension rod equally until the desired pitch is achieved.
With spokes I tend to do the same - get them all equal first and then tighten them all an equal amount but i'm unsure as to how tight they should be. Obviously, too loose and the wheel will be weak, so I assume tighter is better, but is there a danger of going too tight?
With spokes I tend to do the same - get them all equal first and then tighten them all an equal amount but i'm unsure as to how tight they should be. Obviously, too loose and the wheel will be weak, so I assume tighter is better, but is there a danger of going too tight?
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The limitation is what the rim can take, or, occasionally, how tight you can wind them if you don't lubricate the threads.
You need to see what the manufacturer of the rim says; mavic recommend 700-900N, DRC ST19s or DT RR1.1 double eyelets are approved to 1200N, to give afew examples. In practice you can exceed the manufacturer's recommendaton a bit, but not too much as the eyelets pull out or the rimc starts cracking. Older rims went into a pringle shape if you overtightened them, modern ones tend not to.0 -
Park Tools makes a spoke tension gauge that is easy to use and not all that expensive
(60 dollars U.S. - I think). It comes with a chart that tells you how much tension should be on the spokes depending on spoke material and gauge. I find it really useful and have built
a fair share of wheels that have not had problems. A good investment for the amatuer
wheel builder. Some people claim they can tell tension simply by either squeezing the spokes or the sound they make. Me I don't build enough to have that kind of skill so the meter suits me fine. I need all the help I can get.
Dennis Noward0 -
Best to keep in mind that the Park tool gauge is not exactly accurate but can be a guide. The FSA one is accurate but really expensive.There are differing opinions re the best tension as some say as tight as possible without tearing out the eyelets while others look for something less. Evenness of tension is something equally difficult to achieve however and especially maintaining the roundness and dish at the same time.0
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+1 to what robbarker said. More spoke tension makes a stronger wheel, and it is the rim which fails first, thus the rim determines maximum tension. One way to determine this maximum, when no precedent is known, is - in abstract - to build the wheel to partial collapse and then back it off; in practice, doing this is both subtle and complex, and best understood by buying Jobst Brandt's book, "The Bicycle Wheel". Most wheels are with familiar rims, however, so a tensiometer can be used to reapply pre-determined tension. Listening for pitch is accurate if you know what pitch you're after.0
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The Park TM-1 spoke tension tool is not available for under 63 pounds anymore. (I bought the second to last 'cheap' one - 47quid from PBK last week 8) ). A lot of money for what is really a couple of bits of brushed aluminium sheet, some studs, a piece of twisted steel, and a bit of plastic. Still a handy piece of kit though - as onbike says, it's really best just to measure relative tension; although I found out I'd built-up my front Open Pro with only about 50kgf..
Bhima - yes, get all the tensions equal first, and then true-up. Roger Musson reckons you don't need a meter to do this; you turn each nipple by the same amount when building. I guess that after a while (a few years) gauging tension becomes intuitive, and you might even be able to go by pitch - in which case a tuning fork will be cheaper!
Leloby. Speak up!0 -
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Brilliant!
Thanks for the replies!
I may get a tensionmeter at some point in the future, if I start to take all this very seriously although, at the moment, i'm using cheap wheels with no manufacturer info on them, hence, no guidelines to go on... I'm getting some good wheels soon - so I assume you get all the tech info about the rims and stuff when you buy them...?
Actually, i'm a sound engineer/acoustician and regularly use my equpiment to tune instruments in very fine detail and acoustically treat/soundproof rooms using mathematical audio analysis software - so i'm thinking of setting up a microphone so when I pluck the spokes like strings, I can fine tune them to extreme precision in the same way I would with a piano! It'll take ages though!
...so to conclude, is it safer to have spoked over-tightened as opposed to under-tightened?
By the way, i'm pretty new to this so I have another question:
I spent 45 minutes outside UNI, while confused classmates looked on, truing my back wheel using the brakes as a guide today and, as soon as I got on the bike and rode, I heard some strange noises coming from the wheel - clicks mainly. I stopped and re-checked the wheel to find that it was not exactly as true as it was 10 seconds before! What's going on here?0 -
Bhima wrote:Brilliant!
Thanks for the replies!
I may get a tensionmeter at some point in the future, if I start to take all this very seriously although, at the moment, i'm using cheap wheels with no manufacturer info on them, hence, no guidelines to go on... I'm getting some good wheels soon - so I assume you get all the tech info about the rims and stuff when you buy them...?
Actually, i'm a sound engineer/acoustician and regularly use my equpiment to tune instruments in very fine detail and acoustically treat/soundproof rooms using mathematical audio analysis software - so i'm thinking of setting up a microphone so when I pluck the spokes like strings, I can fine tune them to extreme precision in the same way I would with a piano! It'll take ages though!
...so to conclude, is it safer to have spoked over-tightened as opposed to under-tightened?
By the way, i'm pretty new to this so I have another question:
I spent 45 minutes outside UNI, while confused classmates looked on, truing my back wheel using the brakes as a guide today and, as soon as I got on the bike and rode, I heard some strange noises coming from the wheel - clicks mainly. I stopped and re-checked the wheel to find that it was not exactly as true as it was 10 seconds before! What's going on here?
Because a spoke is very narrow, it twists easily when subjected to the torsion of tightening its nipple. This twist is maintained as long is the spoke is in tension. When you load the wheel, tension is relieved as the spoke passes the bottom of the wheel, with a click or ping as the spoke relaxes, undoing itelf partially from its nipple.
This spoke twist should be accounted for during tensioning, by overtightening each spoke about a quarter turn then backing it off. It is a matter of judgment and practice, but a post-it note on the spoke is a good indicator of spoke twist, until you get a feel for it.0 -
What's happening is that by riding the bike after tensioning the spokes you are effectively "de-stressing" them. After truing you are supposed to de-stress by placing the wheel on a flat surface and then with your hands opposite and apart of the rim, bear down with your weight. Repeat on both sides and then re-true until no more de-stressing is required. This is needed as when you tighten the spoke with increased tension, both nipple and spoke turn together and de-stressing releases this so that the spoke springs back thereby screwing up your former truing.
You'll have gathered from all of this that correctly truing a wheel only appears easy and while it may be simple to correct a little lateral movement, it can become more complicated at times.0 -
Bloody hell! Wheel truing is more complicated than I thought! :shock:
I just tried the de-stressing technique and it's doing my head in!
...so lets say I have all the spokes at equal tension (but loose so in need of equal tightening)... am I supposed to do a load of de-stressing every time I tighten all the spokes a little bit? ...and constantly repeat this process until the spokes are tight enough...? It seems like it would take aaaages!0 -
Within reason it is better to be too tight rather than too loose.
On a rear wheel the drive side should be tighter than the non drive.
For the initial tightening just get all the spokes the same length by checking how far down the nipple the end is. When the wheel is no longer floppy tighten each spoke a half turn at a time until it feels nearly there then go to quarter turns. Keep checking that the wheel is fairly true and dished correctly during this process. When you think it is tight enough then do a de-stress followed by final truing and de-stressing. This may need several goes. It will take a while at first but as you get a better feel for it you should be able to build a wheel from scratch in about an hour. Less if you do lots.0 -
onbike 1939 wrote:After truing you are supposed to de-stress by placing the wheel on a flat surface and then with your hands opposite and apart of the rim, bear down with your weight. Repeat on both sides and then re-true until no more de-stressing is required. This is needed as when you tighten the spoke with increased tension, both nipple and spoke turn together and de-stressing releases this so that the spoke springs back thereby screwing up your former truing.
This process removes spoke twist, at a cost of placing stress on the wheel in way's it's not expecting, but doesn't relieve spoke tension appreciably, as far as I can establish from reading all of the reference texts.
Stress relieving is the process of removing the elements of tension in the bend in the spoke that are pushing the metal past its elastic limit. Spokes are made from wire, bent to shape, and the elbow is the weakest area. The best way to stress-relve is to grasp opposing pairs of spokes and squeeze as hard as you can. this stretches the metal in the spoke elbow and evens out the tension across the cross-section of the spoke, making it more resilient to the stresses it will experience in use.
Sorry if this is getting esoteric Bhima, but it's a subject worth getting your head aroundif you want to build your own wheels eventually.
If you have 9ish quid and some time to spare, get the ebook from www.wheelpro.co.uk, or get hold of a copy of Brandt's "The Bicycle Wheel" - only available secondhand now regrettably.0 -
robbarker-very useful and informative post.
Just to clear up one minor point, what do you mean by "opposing pairs"?
Do you mean pairs of spokes on the opposite side of the flange to each other? or pairs that are crossing each other at the point furthest from the hub?0 -
Sorry, I meant grasp pairs of parellel spokes on the same side and squeeze them together hard. (You need leather gloves or similar to fdo ti properly). It was getting late when I posted that :-)0
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[quote="robbarker"
This process removes spoke twist, at a cost of placing stress on the wheel in way's it's not expecting, but doesn't relieve spoke tension appreciably, as far as I can establish from reading all of the reference texts.
Stress relieving is the process of removing the elements of tension in the bend in the spoke that are pushing the metal past its elastic limit. Spokes are made from wire, bent to shape, and the elbow is the weakest area. The best way to stress-relve is to grasp opposing pairs of spokes and squeeze as hard as you can. this stretches the metal in the spoke elbow and evens out the tension across the cross-section of the spoke, making it more resilient to the stresses it will experience in use.
Sorry if this is getting esoteric Bhima, but it's a subject worth getting your head aroundif you want to build your own wheels eventually.
If you have 9ish quid and some time to spare, get the ebook from www.wheelpro.co.uk, or get hold of a copy of Brandt's "The Bicycle Wheel" - only available secondhand now regrettably.[/quote]
There appears to be a bit of a debate about this. According to Roger Masson (pg 56), Mavic recommends the" bearing down on the wheel method" as do several respected wheel-builders, but he along with Brandt is a "squeezer" although he does admit to using the former method but with a block of wood supporting the axle.0 -
It's not as simple as this. You need to increase the tension to a point but once you get to a certain level, even if the rims/spokes/hubs can live with more tension, it is not necessary to add more. It is a function of bracing angles, spoke elbows and more. But simply thinking "more = better" is wrong. Once you get to the point where the wheel is stiff and spoke wind is minimised, then more tension can just make the ride harsh and lead to shorter times until metal fatigue and failure.balthazar wrote:More spoke tension makes a stronger wheel,0 -
Kléber wrote:
It's not as simple as this. You need to increase the tension to a point but once you get to a certain level, even if the rims/spokes/hubs can live with more tension, it is not necessary to add more. It is a function of bracing angles, spoke elbows and more. But simply thinking "more = better" is wrong. Once you get to the point where the wheel is stiff and spoke wind is minimised, then more tension can just make the ride harsh and lead to shorter times until metal fatigue and failure.balthazar wrote:More spoke tension makes a stronger wheel,
I agree "more = better" is wrong. Much more to wheels than simply tightening spokes to the limit(so to speak).
Dennis Noward0 -
Kléber wrote:It's not as simple as this. You need to increase the tension to a point but once you get to a certain level, even if the rims/spokes/hubs can live with more tension, it is not necessary to add more. It is a function of bracing angles, spoke elbows and more. But simply thinking "more = better" is wrong. Once you get to the point where the wheel is stiff and spoke wind is minimised, then more tension can just make the ride harsh and lead to shorter times until metal fatigue and failure.
I strongly disagree. Maximum spoke tension is preferred, because that is when the wheel is strongest. The higher the tension, the later that the loaded spokes become slack, consequently leaving their part of the rim unsupported and vulnerable to lateral collapse. All of this is explained in detail and backed up with F.E.A. analysis in Jobst Brandt's book.
Simply, More = Better.
The only caveat to this is real world limits, such as poorly made rims or wheels with very few spokes which need to be so tight that it is difficult to defeat thread galling.
Secondly, spoke tension has no effect on wheel deflection or "ride quality". The spokes' elongation under load is consistent regardless of their initial tension. In any case, vertical wheel deflection is two orders of magnitude smaller than tyre deflection, and never detectable.0 -
I know what you mean but there comes a point where the spokes will not wind up. When you start the build, for every KGF of tension added, the benefits grow and grow but eventually you get to a point where you can't notice the extra benefits and very quickly the costs of extra tension rise. So I am not saying make slack wheels, only you don't have take the tension to the max, especially as many will think more = better if they give this a casual read.
Indeed my philosophy should be to build wheels with the lowest tension possible, once the wheel is tight. In other words, you minimise spoke wind up and target this instead of the pure tension.0 -
The problem on here is how to define the optimum tension. I would suggest that most cheap wheels are below this thus the spokes come loose. I have built enough wheels now to know when to stop winding but without a tension guage this only comes with experience. Spokes should 'ping' when flicked. If they sound dull then they are almost certainly too slack. If you are having difficulty turning the nipples then you have probably gone too far. Try to get the feel of a quality hand built wheel and use that as a guide. None of this is rocket science but it is a skill to be learned.0
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I alluded to one method for establishing correct tension earlier in this thread, but will expand, as robbarker has taken the effort to explain stress-relieving.
Keep increasing the tensioning, in small increments, until stress-relieving causes the wheel to collapse into a gentle saddle shape. This is the maximum tension that the rim will tolerate. Then, back off the spokes a half turn, and true to finished. The final tension can safely remain this close to the maximum, because tension only decreases in use, rather than increasing.
This method requires care and is time consuming. I last did it some years ago for Open Pro's, previously having done so with MA2's. Since then, I have trued by pitch, happy that I am within shouting distance of the optimum tensions I ascertained then. I have never had a tensiometer, though if I built wheels often enough to justify it I'd get that FSA one like a shot.
Edit to add tensiometer link:
http://wheelfanatyk.blogspot.com/2008/0 ... -news.html0
