Bicycle Mechanics - 4 cross lacing question

I have laced up a few wheels, but never with a 4 cross pattern. When I was talking to the LBS the mechanic told me that you need multiple spoke lengths to do this pattern. I understand that due to dish, you may need different spoke lengths for the left and right side of the rear wheel. The mechanic however told me that I will also need different spoke lengths with respect to one side of the wheel and that he didn't know why or how to figure out in advance what lengths. I can't find in any of my books or online a mention of different spoke lengths neccesary for a four cross pattern. Has anyone heard of needing multiple spoke lengths (with respect to one side of the wheel) for the four cross pattern? If so, how I can figure out the other lengths.
Thanks

I don't think so but have no experience with 4 X. Have you tried an online calculator like the one at DT Swiss?

Al

Do a google search for spocalc.xls - it's great free spoke length calculator.

Switching to 4-cross won't require two lengths of spokes per side.

The mechanic obviously doesn't design wheels. However, a 4-cross spoke pattern is not much stronger than a 3 cross, yet suffers from a serious deficiency in that each spoke is probably going to overlap another spoke head. If you ever break a spoke, replacing it may be a real pain. Just something to consider before you buy a bunch of spokes...

I have experience building wheels for tandems. I use 4 cross on 40 spoke wheels and 5 cross on 48 spoke wheels. With fewer spokes at some point the spokes that go in one direction will overlap the heads of the spokes going in the opposite direction and create some unnecessary problems. I generally build 32 and 36 spoke wheels cross 3, and 28 spoke wheels cross 2.

If you think about it, the spokes on either side leave the hub flange at the same angle regardless of whether they face forward or backward. Consequently it's exactly the same distance from the hub flange to the rim. That's independent of the number of spokes.

5 cross? whoa. I didn't know there was such a thing.

Remember, a 36 hole hub is the minimum for 4X lacing.

Remember also that the crossing only affects torsional rigidity of the wheel. Lateral and vertical stiffness or strength won't be any different.

I have laced up a few wheels, but never with a 4 cross pattern. When I was talking to the LBS the mechanic told me that you need multiple spoke lengths to do this pattern. I understand that due to dish, you may need different spoke lengths for the left and right side of the rear wheel. The mechanic however told me that I will also need different spoke lengths with respect to one side of the wheel and that he didn't know why or how to figure out in advance what lengths. I can't find in any of my books or online a mention of different spoke lengths neccesary for a four cross pattern. Has anyone heard of needing multiple spoke lengths (with respect to one side of the wheel) for the four cross pattern? If so, how I can figure out the other lengths.
Thanks

In honour of sydney - Rubbish,

One length per side - number of spokes per side must be divisible by 4

Thanks everyone for the information. I figured the mechanic was in error.

Remember also that the crossing only affects torsional rigidity of the wheel. Lateral and vertical stiffness or strength won't be any different.

He's right, it only affects torsional rigidity. And thats why, if my memory serves me,a 4 cross rear is the way to go because with 4 cross, the spokes are coming off the hub in a perfect perpendicular direction, so that all the drive from the hub gets transfered to driving the rim. I also mirror lace the rear so that the driving spokes are on the inside of the hub, that way the drive spokes are bent the least amount and have less of a tendency to break.

The angle at which the spokes leave the flange is a bit more complex, involving the number of spokes the wheel has. But anyhow, a well-built, appropriately-spec'ed wheel of either design will last until you're sick of it. *glares across room at Cannondale full-tourer, still stuck in 7-speed land by its ca. 1997 wheelset :p*

Website for Spocalc spoke length calculator. "Full" version includes good variety of rim and hub data.
http://damonrinard.com/spocalc.htm

... number of spokes per side must be divisible by 4...

Rubbish. :) You can build a 36 and 44 spoke wheels using a 4-cross pattern. That's 18 and 22 spokes per side which are not divisible by 4.

Originally Posted by toomanybikes... number of spokes per side must be divisible by 4...

Not correct. The number of spokes per side for cross-laced wheels must be divisible by 2. For radial laced wheels even this isn't necessary. There are several 18 spoke radial laced front wheels available with, obviously, 9 spokes per side.

...a 4-cross spoke pattern...suffers from a serious deficiency in that each spoke is probably going to overlap another spoke head. If you ever break a spoke, replacing it may be a real pain...

Doesn't using a 4-cross pattern reduce the likelihood of breaking a spoke significantly? If the spokes'll never break, who cares if the heads are overlapped? I'm not arguing with you here, I'd honestly like your feedback on these questions. Thanks! :)

Doesn't using a 4-cross pattern reduce the likelihood of breaking a spoke significantly? If the spokes'll never break, who cares if the heads are overlapped? I'm not arguing with you here, I'd honestly like your feedback on these questions. Thanks! :)

No it doesn't. It's a bit easier on the hub flanges since with 36 hole rims, the spokes are almost perfectly tangential to the flange. However, there is no reason it should be easier on the spokes.

These days, spoke breakage using DT, Wheelsmith or Sipam spokes and a 32 hole 3x pattern properly laced and tensioned is so rare as to be a non-issue. The rims will wear through and crack at the brake tracks or pull through at the spoke beds before any of the spokes break. I've had 32 hole 3X wheels last 30,000 miles and be replaced because of rim failure and NEVER broken a name-brand spoke. Worries about spoke failure are a remnant of the old mild steel plated spokes of years ago or the result of very poor lacing technique.

In fact, the durability of modern spokes is what makes the current crop of very low spoke count boutique wheels possible.

I use 4x wheels on my 48 sole bmx wheels, and they are definitely tougher than 3x provided the hub flanges are big enough for the spokes not to cross the spoke heads. However when you start to factor in dishing then I'd be far less sure of the advantages.

I have found that 4-cross wheels provide a slightly more compliant ride than say 3-cross. So, when I lace up a wheel for use on a touring bike, I use a 4-cross spoke pattern.

Jason

I have found that 4-cross wheels provide a slightly more compliant ride than say 3-cross. So, when I lace up a wheel for use on a touring bike, I use a 4-cross spoke pattern.

Jason

This myth just won't go away.