/5 assymetric front wheel lace-up?

I just made an astounding (to me, anyway) discovery...

The spokes on the front wheel of my LWB /5 appear to be laced asymmetrically; there is about .090" clearance between the spokes on the left side, but on the right side they actually touch, in fact they more than "touch"; the spokes deflect (almost imperceptibly) to get past each other.

Everything I've ever read says that spokes do not touch each other.

So this is a "poll" question; Do the spokes on YOUR /5 touch on either side, or not. And if not, how much space is there between them?

The strange thing is my /5 handles really well; and the front wheel has never been touched to my knowledge.

Duane has an article on wheels and spokes:

http://w6rec.com/duane/bmw/spoke/index.htm

I don't think the spokes are supposed to touch. The reasons in your case might be too much offset or wrong spoke size. Duane mentions a change in spoke designs for the early /5s.

Thanks for that Kurt. I had scanned through it previously but missed the reference to spokes touching.

I suspect, strongly (now), that the rim was installed "backwards". Our local "classic motorcycle club" had it's monthly breakfast yesterday and I was able to hook up with our ABC techie ... new Buchanan stainless spokes sets are on order as we speak. Won't know if the rim is a goner until he breaks it down.

Weird that this wheel has lived soooo long set up as it is, and not a single loose spoke. Maybe, shoulda, checked this situation out prior to putting on the new Spitfires... oh well.

If your rim is original, it'll have an arrow on it.

where...?

Lew,
I just checked out my R75/5's (2), on only one pair of spokes was I even able to slip a .003 gauge between 'em.

I pulled down a spare front wheel (no tube or tire) hanging from a rafter, and each pair of spokes easily passed a .020 gauge.

I'm not sure what to make of that.

Mine have at least .022 spacing at each crossing.

Lmo1131 said:

where...?

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I found arrows on the bead seat, near the valve hole, where the other rim size information lives. They may be hiding in 30+ years of built up rubber schmuck.

Of course, I found this after I laced them up when this thread pointed me to them. They are going the right direction (whew!).

I come to this with a whole buncha experience lacing bicycle wheels, where we endeavor to not only have the spokes touch, but to actually pass the other spoke on the side contrary to how the spoke exits the hub. We find it adds rigidity with our wee 1.8mm spokes. Clearly it's not necessary with the 4.0mm spokes on our Airheads and likely undesirable. Still, I had to constantly stop myself from trying to cross them over when I was lacing the wheels.

None of mine touch where they pass by.

New Buchanan stainless spokes are going in, or at least they were going in...

You will recall (from the above discussion) that my spokes were touching on one side. When the mechanic got to the last ten spokes they would not fit with deflecting (so the wheel remains on the bench).

I am now learning that the /5 front wheels require "offset".

A search of the forum revealed no previous discussions about offset.

Does anyone know the amount? Or to which side (I'm guessing toward the brake).

Thanks.

Duane discusses this on his page:

http://w6rec.com/duane/bmw/spoke/index.htm

Not sure if it's the right detail that you need. But this is the only place I've seen this discussed.

Lmo1131 said:

I am now learning that the /5 front wheels require "offset".

A search of the forum revealed no previous discussions about offset.

Does anyone know the amount? Or to which side (I'm guessing toward the brake).

Thanks.

Click to expand...

On my /6 rear the measurements I took before disassembling the wheel, laying a straightedge across the hub flange and measuring the gap at the rim, were 2.5mm on the left and 6.2mm on the right. This is, of course, with a 2.15" rim width. I did not have to tighten one side more than the other to achieve this when I laced the new one up. Your /5 hub may be different.

Duane's article refers to the /2.

I wrote him last night:

I can't remember the offset for the /5. My own wheels are mounted up, so can't be measured. I did measure the space between the spokes. I used 3 feeler gauges and they average .070" with some small variation of maybe .005" or so. The wheel is stock. The SS spokes are usually a bit larger. Just measure the two diameters and do the subtraction to get an idea.

Click to expand...

It occurred to me last night that your thread title, unintentionally, might have spoken to me. On bicycle wheels, lacing patterns are typically up to the builder and we make reference to "symmetric" and "assymmetric" patterns (we also fuss a bit much about it and will come to blows over it when we're drunk). All the /5 and /6 drum wheels I've observed (not many) are symmetric to a bicycle guy, in that the lacing pattern on each side is a mirror image of the other, slightly offset. Like so:



The /6 disc wheel, however, is assymmetric. The hub is cast in two identical halves, so the spokes do not form mirror images. Like so:



Now when building a bicycle wheel with hubs like that, it's NBD. Bicycle rims almost always have their drillings with just an alternating "left" and a "right" orientation. The Weinmanns on our Airheads, however, add an "inside" and an "outside" to the mix. Observe here my rear (drum) wheel, drilled for "symmetric" lacing. Spoke holes are, left to right from the valve hole, drilled outside/outside/inside/inside:



The front (disc) rim, drilled for "assymetric" lacing, has spoke holes drilled outside/inside/inside/outside:



What I'm getting at here, is do you have possibly a front rim that was drilled for a disc hub and "assymmetric" lacing? I would expect, from what I've observed, that using such a rim would lead to one side's spokes touching.

... or a post '74 rim (requiring no offset) was laced onto my drum hub (that requires offset)?

The thought plickens....

Offset Diagram Ref. http://forums.bmwmoa.org/showthread.php?t=46463

Okay... here's a bit of closure, if anyone is interested.

The spokes on the front wheel of my trusty old R75/5 were deflecting around each other because.... ?

At some point in his short stewardship, the PO had a /6 front rim laced onto my /5 front drum-brake hub.

The /6 wheel utilized a "spool" for it's new disc brake system and required a specific rim [36311233321] vs [36311233323 (on the /5)] and longer spokes [176mm vs. 153mm].

The Gods were smiling that day and I as able to purchase an entire /5 front wheel on FleaBag for $130 [OEM rim; $352]; stripped out the old spokes, installed the new stainless Buchanans and everything is good again.

The bike had 1,100 miles on it when I bought it and based on a few peculiarities discovered over the years I've long suspected that violence played a part in it's childhood.

CASE CLOSED

Glad to hear it's resolved. Wrong rim installed in only 1100 miles? Perhaps PO crashed, got it fixed, and gave up on the two wheeled thing?

Perhaps PO crashed, got it fixed, and gave up on the two wheeled thing?

Click to expand...

Lucky for us, huh? One less hazard to navigation.

And lucky for The Old Man, we've been hangin' out together for 34 years now.