mbusha

I'm a novice wheel builder who has made maybe 3 sets at this point, all x3. I wanted to try my hand at something new. Last night I rebuilt an old front wheel that wasn't in use (and horribly out of true) as a three-leading three-trailing, and want to check to make sure I didn't do anything stupid. The wheel was stock off a Trek 520 with a Deore LX hub, Bontraiger Fairlane rim, and straight-gauge 2.0mm spokes (couldn't identify the brand). I repacked the hubs and, with the exception of some rust on the locknuts that didn't seem to extend any further inside, the hub, rim, and spokes all seemed to be in fine condition, so I just got some new nipples and re-used everything else.

Interlacing the 3-leading 3-trailing pattern was definitely more tricky than I had anticipated (and I had to do it twice since I got valve hole in the wrong place the first time ). In the end, I think the wheel looks really nice, but the spokes have some serious bends where they're interlaced. Also, I think I threaded the spokes into the incorrect rim holes (i.e., the spokes from the left flange go into holes on the rim that are offset slightly to the right). This was necessary in order to align the valve hole, but seems to cause an extra bend where the spoke comes out of the nipple (see the third picture). Is this normal/safe for this patter? Or did I do something stupid/wrong? Hopefully it's not crazy to use 2.0mm spokes for this pattern.

Finally, I realized after building the wheel, that the spoke-holes in the hub are the wider 2.6mm size. I know that some people (i.e., Schraner) recommend using spoke washers in this situation, although the original wheel didn't have any. Am I asking for trouble by not using any? FWIW, the original wheel never had any broken spokes after a few thousand miles. Thanks for any advice.

Mark Kelly 

Yes, you did something wrong. It isn't difficult to get the 3 leading 3 trailing pattern to work with the spoke hole alignment. It's harder to correct it once you've botched it but here is one way of doing it:

Loosen tension on all spokes.

Unlace one side of the wheel completely. This should be the side that has a trailing spoke next to the valve hole.

Undo the other side spokes one by one and move them back one hole; eg the spoke that was next-plus-one to the valve hole moves to next to the spoke hole, and so on all around the wheel.

Relace the other side which now goes one place forward of where it was.

You will now have the correct pattern.

If this is too complicated to follow, just unlace the wheel and start again. You have a 50% chance of getting it right.

mbusha

Thanks. You're instructions were completely cryptic to me at first, but after staring at my pictures for a few minutes, I think I understand what needs to be done (and now your instructions seem perfectly clear!). I'll re-lace it tonight and hopefully do it correct. Third time's the charm!

Mark Kelly 

OK that sounds good. I'm glad you were able to decipher my gobbledegook.

I do some design work and have written a few sets of instructions for various bits. It's amazingly hard going from being totally familiar with something, having nurtured it from conception to completion, to imagining yourself in the shoes of someone who has never seen it before.

dabac

Well, longevity isn't the reason for choosing that pattern...

No and maybe. Having a pronounced bend at the nipple may cause spokes to break just at the start of the threads. Whether/when you'll see that happening is impossible to predict.

No and yes. Your spoke sequence is off. There is a sequence which'd let you have both the valve in the right position and have the nipples properly aligned.

It's an interaction between spoke hole diameter and hub flange thickness. The key is to have as much as possible of the bent part of the spoke supported by the hub flange. The diameter of the spoke hole as such isn't particularly important, but a bigger hole allows the spoke head to seat further in, causing more exposed ben at the other side.

No way to tell. I've seen wheels built around steel shell hubs with really thin flanges that has held up for ages.

mrrabbit 

Mistakes = Yes

Am I going to suffer a horrible crash and die screaming "Oh dear God, call my mother to me to save me!" = No

It's a front non-disc / non-drum wheel.

Next time you do one of these - use 13/14 guage spokes (cost more) - and check the rim centerline before building.

This way you:

1. Get it laced right the first time.
2. Will less likely suffer spoke breakage.

Cause you really don't want to have to re-lace one of these to begin with - nor do you want to have to practically detension the entire wheel each time you need to replace a spoke.

Better planning = Less headaches

=8-)

BCRider

I would "weave" the spokes differently to avoid the sharp bends you're getting. If you look at regular 3x wheels there is a bit of a kink where they cross farther out but they don't weave the spokes further in where they cross in order to avoid the bad reversals you're getting. As they sit now they are not in straight lines other than the cross over bends. Instead they have a long segmented curve as seen from the side due to the high interwoven points producing a lot of pressure. Basically avoid the inner cross overs near the flange.

Mark Kelly 

No, he's got the weave right except that the last cross (first leading over last trailing) is normally reversed but this is the outermost and therefore least important cross.

Working from the inside out:

The first two crosses of the "inner" spokes are constrained by their position WRT the flange, they must go over over and under under respectively. The last cross is complementary otherwise there wouldn't be a weave on these spokes.

The first cross of each "middle" spoke has been dealt with above, the second cross is complementary, the last cross is the complement of that complement.

The first two crosses of the outer spokes have been dealt with above which leaves only the last cross of these spokes, it's usually complementary for symmetry.

Writing this as a cross table where the number pairs refer to the spokes and the X or O refer to under or over we have:

1,1 X ; 2,1 X ; 3,1 O
1,2 X ; 2,2 O ; 3,2 X
1,3 O ; 2,3 X ; 3,3 O

You cannot change any number pair which sums to 3 or less due to flange constraints.

The first available change is the second entry in the second row. If you were to reverse this and then make the changes that symmetry requires, you would have

1,1 X ; 2,1 X ; 3,1 O
1,2 X ; 2,2 X ; 3,2 O
1,3 O ; 2,3 O ; 3,3 X

I see no advantage in this pattern.

mbusha

I just wanted to say thanks for the suggestions. As several people noted, I had the centerline off, and correcting that made the spokes stick out from the nipples at a much less frightening angle. I re-laced the wheel per Mark Kelly's suggestions (and even managed to follow his diagrams!), and the spoke angles look much more reasonable. I stared at the weave for a while, trying to figure out how to avoid some of the worst-offending kinks and wasn't really really able to come up with anything that didn't leave at least one pair of spokes that weren't interlaced at all. I'm guessing that having a spoke that isn't interlaced is a bad thing (but maybe I'm completely wrong since it's effectively what radial spoking does -- I'm sure someone here has knowledge on this subject!)

To ask about mrrabbit's comment,

Is the implication that using different (butted) spokes would make it easier to change a spoke in the event of a breakage? I would definitely believe that the lacing patter I used is one of the harder ones for changing a single spoke, but would simply switching to a butted (and more flexible) also make it significantly easier to replace one spoke? Or were you just suggesting that the crazy nipple-spoke angle made it much more likely that I would break a spoke?


The upshot of all this is that, since the sharp bends in the spokes near the hub still look kind of scary to me, I think I'm over the desire to try more "exotic" lacing patterns for a while. Everyone goes through this phase when learning how to build wheels, right?

fietsbob

just wonder if weaving of spokes, is needed at all .. ..

might just tie and solder the near crossing points, instead.
pattern remains unchanged..

or just the last cross, thats the pattern for normal wheels ,
outermost cross is where the weave takes place.

Mark Kelly 

Glad it worked out.

Regarding the weave pattern, if you follow the logic of the decision tree outlined above, you'll see that there is only one other pattern that doesn't give unlaced spokes and it doesn't affect the most serious bends.

As far as I am aware unlaced spokes are not a mechanical problem but the whole point of 3L 3T is to generate the trefoil weave which would be less distinct with unlaced spokes.

My son rides a 3L 3T wheel on his school commuter and it gives no trouble despite having been built with a 10 year old Mavic rim, re-cycled spokes and a 20 year old Campy hub. Only the nipples were new - we built his bike from the parts pile in the shed, I only had to buy a new crankset, new bars and stem and a new rear rim.

mrrabbit 

I suggested single butted spokes (13g/14g) to provided more beef at the elbows/heads to help forestall spoke breakage.

It's usually extra work replacing a spoke with this lacing pattern...

=8-)