Hope Hoops loose spokes!

kwikee

kwikee

Likes Dirt
I got a set of new Arch EX hoops about 4 months ago and after reading how spoke tensions are known to be quite low with them, thought I'd check mine after sensing the rear was a bit out of true.


Found two consecutive spokes on the non-drive side of the rear were so loose, they were at risk of having the nipples fall out, and the others with a bit of variation in tension (using the iPhone app). I won't quote the numbers since I doubt their accuracy, however for consistency there was more than 10% in it.

Funny thing is, I went over both sides, back and forth until I had consistent tensions for all spokes, both sides (obviously higher on the drive side and the disc side for the front) and upon finishing found the front to be perfectly true, and the rear out by about 3mm in two places. I've since re-trued the rear and have yet to check it again, but surely this shouldn't be right? I'll take it for a quick spin to settle them down and then re-check, but I thought the wheel should be very close to spot on if the tensions were even. Any thoughts?

Also, what's the opinions on the iPhone app Spoke Tension Gauge by pepelko? I doubt it's accuracy, but I figure based on vibration frequency it should be good enough to show consistent tension.
 
T-Rex

T-Rex

Template denier
You can have perfectly even spoke tension and still have the wheel out of true. Getting it true with even tension is the "art of wheel building". Takes patience.

Don't know about that app, I presume it relies on the tone of the spoke when you strike it ie F Sharp. I don't have a musical ear, so I use a Park tension gauge .
 
mitchy_

mitchy_

Llama calmer
an even tensioned wheel does not a true wheel make.

i'd be taking it to a pro over a $1.99 phone app. last set of wheels cost me $40 to check and true, not expensive.
 
redbruce

redbruce

Eats Squid
T-Rex said:
You can have perfectly even spoke tension and still have the wheel out of true. Getting it true with even tension is the "art of wheel building". Takes patience.

Don't know about that app, I presume it relies on the tone of the spoke when you strike it ie F Sharp. I don't have a musical ear, so I use a Park tension gauge .
Click to expand...
^^^This. I used to be "calibrated" pretty well as I was regularly either building or repairing wheels. Not so more in the last 12 months and I have lost my "hand" (and ear), as it were.

Tried the app, and subsequently bought a Park Tool tensiometer. Not perfect, but more so than me with or without that app.
 
pharmaboy

pharmaboy

Eats Squid
An even tensioned straight rim produces a straight wheel.

An even tensioned bent rim does not.

You shouldn't just straighten a disc braked wheel with tension - it is weaker as a result, and some wobble is no problem. The world of bike shops however is littered with people who learnt to build road wheels where straightness is critical and apply exactly the same rules to Mtb rules.

Anyway, take it to a shop - $25 well spent, and if you want to do it yourself, get a park tool tensiometer and check them often and read a bit about it.
 
kwikee

kwikee

Likes Dirt
pharmaboy said:
An even tensioned straight rim produces a straight wheel.

An even tensioned bent rim does not.

You shouldn't just straighten a disc braked wheel with tension - it is weaker as a result, and some wobble is no problem. The world of bike shops however is littered with people who learnt to build road wheels where straightness is critical and apply exactly the same rules to Mtb rules.

Anyway, take it to a shop - $25 well spent, and if you want to do it yourself, get a park tool tensiometer and check them often and read a bit about it.
Click to expand...
It would seem it was out of true due to the spokes being loose, so why wouldn't tightening them straighten it again? Logic says that in a perfect world, even spoke tension should produce a wheel that is both true and round. The wheel has not been damaged, just moved a bit due to some very loose spokes.
I think a spoke tension gauge may be a good investment.
 
frenchman

frenchman

Eats cheese. Sells crack.
^not really. The wheel being new will have the spokes 'bed in' (the j bend will conform around your hub flange a little bit tighter) and it doesn't all happen at once.
 
MARKL

MARKL

Eats Squid
kwikee said:
It would seem it was out of true due to the spokes being loose, so why wouldn't tightening them straighten it again? Logic says that in a perfect world, even spoke tension should produce a wheel that is both true and round. The wheel has not been damaged, just moved a bit due to some very loose spokes.
I think a spoke tension gauge may be a good investment.
Click to expand...
No. When you build a wheel from scratch you build up the tension gradually, all the spokes interact. At the same time you are trying to make the wheel straight and round. Tension, straightness and roundness all interact.

Trying to give a simple example to illustrate, say you have a two spokes on opposite sides of the wheel with a length of 260mm each, they have about 10mm of thread on the end. Once you tension it up properly say you use 7mm of that 10mm of thread and that gives you the required tension. However if you used 10mm on one side of the wheel and 4mm on the other you would get similar tension however the wheel wouldn't be straight or round. Hope that example worked.

If you then apply that logic to 1 or 2 loose spokes out of 32, those loose spokes are interacting with all the other spokes when you tighten them up. Which is why you can get similarly tensioned wheels with vastly different results for straightness.

The other thing to keep in mind is that as you get to full tension, the changes in tension have a greater effect on straightness. It is super easy to build a straight wheel with low tension, it is much harder to build a straight wheel with high tension, it is harder again to build a straight wheel with high and even tension.

And as Pharmaboy said straightness isn't absolutely important for disc braked wheels. Even tension is far more important for strength and longevity.
 
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kwikee

kwikee

Likes Dirt
Yep, good response. I've got the rear straight again, will ride it for a bit and see how the tensions feel again. As long as nothing is super loose, I'll leave it for now.
 
XYGTHO

XYGTHO

Likes Dirt
Also patience is needed lol. I recently got a Part Tool tension meter. Good investment if you have a few sets of wheels. One set of wheels I have evenly tensioned and wheels was perfectly straight as a result (Arch Ex). Another wheel I tensioned evenenly off the bike to true and it had a massive wobble (learnt that lesson!). Managed to get it straight, and pretty even tension just took some patience (Race Gold - very light rim). I just use zip ties on the frame/fork and cut either side of the wheel.
 
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