Park Tesionmeter ... what's the best way to use it?

[Jimmy Doug]

Got one at last! Yes, after years and years of thinking "I really need to get a tensionmeter", I finally took the plunge and ordered one - after spending less on a truing stand (one of those Spin Doctor ones). Anyway, thing is ... just how do you use it? I mean - what's the best way? The thing does come with some semi-decent instructions, but there are a couple of points that remain unclear to me:

• Do I start by checking every spoke and tightening those that are loose (and loosing those that are tight) or do I just take the average tension and, if it's not what it should be, tighten the loose spokes?
• How do I use the chart exactly? Having ascertained the material the spokes are made out of and their diameter, do I accept any reading in the chart for which there is an entry? For example, assuming I have 2.0 mm round steel spokes, is an acceptable reading on the tensionmetre anything between 14 and 25 because those are the entries that Park has filled out in the conversion chart?
• My wife's wheels have loads of loose spokes and the wheel is starting to get out of true. Would the best procedure be to go around tightening the spokes with the assistance of the tentionmetre and then true, or would it be better to true the wheel first then tighten all the spokes by an equal amount?

Thanks for any help!

 

[PpPete]

You'll need to get a certain amount of tension on the spokes before the tool will register.
I don't use mine for truing, but when I'm building wheels I aim for a reading of at least 20 on the front and the rear drive side. Usually more like 22.
Non drive side is typically around 18. But more important is to get them even. So if I average say 21 on the drive side I make sure all those spokes are between 20 and 22.

Although it's more about building than truing, these videos are good.

 

[Jimmy Doug]

Wow! Those videos are amazing! I've been looking around for something like this for ages - thanks for the links! But just how do I use the chart properly, though? Is what I said in point 2 above correct?

 

[PapaZita]

But just how do I use the chart properly, though? Is what I said in point 2 above correct?

The chart will allow you to translate a reading from the tool into an actual tension value. A rim maker will often publish a maximum spoke tension for a rim, often about 1000 N or 100 kgf. Spoke tension causes compression in the rim, and if it's too much the rim will start to buckle. Generally, for the strongest wheel, you want the highest tension that you can achieve, provided that it's lower than the manufacturer's recommended maximum.

When building a wheel, I tend to take the max tension, and convert that to a reading on the tension gauge, e.g. 18. Then, as I tension up the wheel I know not to exceed 18. If I find that I have to stop at, say, 17, that's fine. Then, the important thing is to get a consistent reading of 17 from each spoke. I'll usually start by tightening each spoke the same amount, e.g. So that the last thread just disappears into the nipple, then measure the tensions and adjust until they're almost equal, although they might not be at full tension at this stage. From then on it's a process of testing roundness, trueness, dish, and tension, deciding which is worst, and adjusting for that. If the rim needs to move, think about whether there is a particular spoke or spokes that can achieve that movement while also moving towards more even tension.

For fixing up an existing wheel, it depends how bad it is. If really bad, consider slackening off all the spokes and proceeding as if building a new wheel. Otherwise, probably start by tightening up the loosest spokes. You'll probably find that tightening the loose spokes will also pull the rim back towards the shape you want. Bear in mind though that if, say, tightening a spoke on the left, and pulling the rim that way, you'll also increase the tension of the spokes on the right a bit. Everything interacts with everything else. Think of the side effects of the adjustments you make, and gradually make smaller and smaller adjustments until everything converges into the best possible result.

Hope this helps.

PZ.

 

[Jimmy Doug]

Thank you very much PapaZita. That's very clear.

Generally, for the strongest wheel, you want the highest tension that you can achieve, provided that it's lower than the manufacturer's recommended maximum.

What do you do if you don't know the manufacturer's recommended maximum? The problem for me is that on my bike I suspect the wheel is Shimano, but I don't know for sure because although the hub has a Shimano label with a model number on it, there's nothing on the wheel; as for my wife's bike, I have no idea what make the wheel is (it's an old 1980s woman's racer), yet alone the model number! In the instructions, Park give the rule of thumb that anything between 85 and 115 kgf should be acceptable - but isn't that a risky assumption on an old wheel?

Thanks once again

 

[PapaZita]

What do you do if you don't know the manufacturer's recommended maximum?

That's a good question. You may have to guess a bit! Can you measure the tensions on the other wheel, if that's in better condition? If the wheel you're working on only has a few loose spokes then the tension of the tightest spoke may still be a reasonable guide.

If you do have to guess you can be guided a bit by the type of rim you have. There are two main symptoms of too much tension. The first is that the rim starts to buckle as you're building the wheel. This is more likely with lightweight rims. It isn't the end of the world, as you can reduce the tension and try again before any harm is done. The second is that the rim fails around the spoke holes, normally after a certain amount of use. Rims with eyelets can generally take a bit more tension than rims without. Some, like Open Pro have double eyelets which spread the load to the inner rim, and are even stronger. Being quite light, with double eyelets, you can generally find max tension of a rim like an Open Pro while building it. A more chunky rim without eyelets is at the other extreme, where you would need to be more careful, and it might be more appropriate to aim for a lower tension to be safe.

PZ.

 

[Jimmy Doug]

Thank you very much for your advice. I will tell you how it goes - although the truing stand hasn't even been sent yet so it might be a few days before I can have a go.

Cheers

 

[Jimmy Doug]

I had a look at my wife's wheels this weekend and followed what you said. No problems at all. The wheel is now as straight as I can make it. The tensiometre is a really great tool - definetely worth the investment.

Cheers once again