Optimal spoke tension?
 

I'm building my first wheelset and have my wheels laced and the front wheel fairly true (still need to stress relieve and might need to do a better job of making sure the elbows are flush against the hub, so I have a ways to go though). One thing I don't seem to have a handle on is how much tension to put on the spokes.

I tried a basic google search but didn't come up with an obvious number/table for the spokes I'm using.

I'm using Sapim Race spokes (14-15-14 double butted). Also Mavic XM317 26" rims and some Shimano 105 hubs from the late 90's (old but unused) if that matters. Anybody have access to a nice table or solid number I should be shooting for? Sorry if it's somewhere obvious that I'm just missing.

Also, I'm using Park's tensionmeter (TM-1?). It comes with a conversion table for converting meter readings into tension based on spoke thickness. Since my spokes are double butted, I wasn't sure which conversion to use. I was assuming that, since I'm measuring tension in the 15g region of the spoke, that I should use the 15g conversion factor rather than the 14g column, right?

Once again, thanks for all your help.

Generally, the rim manufacturer give a recommended spoke tension. Use the 15g tension.

Hmm, so I need to find out where the optimal spoke tension for my rims is, I guess then. Doesn't look like Mavic makes that information easy to find either.

huh, it looks like someone says that Mavic recommends 70-90 kgf for most of their rims. Can't find it on Mavic's site anywhere. Does that sound like reasonable range? I just checked a set of wheels I bought recently (also mavic rims) but haven't mounted yet that the guy said were machine built but then retensioned and trued by hand and that had spokes in the 100-125 or so range, so I was sort of surprised to see mavic's recommendation being lower so low.

I uually go for 110kg on a 32 to 36 spoke wheel. Fewer spokes will require more tension.

Yeah these are 32 spokes wheels. I've been following Sheldon Brown's directions for 3x wheels. I should probably post some pictures to make sure they look like they're laced right. I was surprised at how much of a tangent the trailing spokes come out of the wheel.

And if I get the wheel all true and everything (and stress-relieved), if it's below that tension, I just turn all nipples equally until it's roughly at the right tension, right?

Also, if they're true, but the tension isn't even, should I leave it, or how do I address getting tension even without losing true?

Mavic provides number in Newtons which when converted come out to about 111-113 kgf for their rims. (Not their proprietary wheels...).

Use the the "Round 1.8" column on the Park Tool chart...make sure the tool only clamps the 15g portion of the spoke.

Get the front up around at least 95 kgf.

Get the rear drive side up to or close to 110 kgf with wheel trued AND dished.

=8-)

Also to answer you other question, Mavic on occasion will give you a rim where the spokes near the joint will not have tension in the same ballpark as the others. I.e., you might have one undertensioned and one overtensioned.

=8-)

I tighten mine until one nipple strips then I back off 1/2 turn and replace the nipple.

So you choose to purposely destroy a nipple when there are simpler and more straightforward ways to get the tensioning job done. And then you reward yourself with a local detensioning and retensioning for nipple replacement that wasn't necessary to begin with - and more wheel true, dish and tension cycles in order to finish...only to be back right where you started:

Unsure of where you are at.

Um...okay...

=8-)

Sounds like a good way to gain experience.

If you really want with shallow moderate weight box section rims like that and conventional (32, 36, maybe 28) spoke counts you can iteratively add tension and stress relieve (overload the spokes thus taking them past their elastic limit. You can squeeze near parallel pairs together (gloves make that more comfortable) or bend spokes around each other at their outer crossing using something softer (I like a big brass drift although other people use an old left crank or plastic screw driver handle)) until the wheel goes out of true in waves on the stress relieving phase (indicating you've exceeded its elastic limit) at which point you back off half a turn, true, and be content.

The last wheels I built that way (Mavic Reflex front, Open Pro rear, MA40 rear) ended up around 110kgf front and rear drive side which is exactly what I tried for after getting a Park TM-1.

Where you lubricate properly that will be way too tight and cause stress cracks, and where you don't with old nipples it can be loose enough the wheel won't stay true.

See, you'll learn all kinds of things.

Not everybody wants or needs a tension meter. I don't trust them to be accurate and there is no science for how tight a spoke should be. You can build wheels without fancy equipment. I use motor oil for the nipples there is always some in a parking lot.

What nipples do you use? Normal nipples would round before stripping in my experience. And a low profile rim would be tacoed before stripping.

You don't suppose that there's a relationship between your wheel tensioning technique and your rim failures, do you?

http://www.bikeforums.net/showthread...1#post14195320

<snicker>