Reference Points for Wheel Lacing

I am about to lace up a set of wheels for my '72, with front disk, rear drum. I have searched and read countless posts and made a visit to Old Britts, Technical Articles and now know whet the offsets are and in which direction they favor, but Fred does not define the reference point from which to measure the offsets; and I'll admit that I did not read all 965 posts that my forum search turned up as most had nothing to do with wheel lacing.

I am no stranger to wheel lacing, which I generally find quite relaxing. I recently finished a set of wheels for a BMW R100 where the reference points were very well defined and easy to measure.

So my question:

Front rim is a WM-2, Old Britts uses a WM-3 for their specs, can anyone tell me how to establish reference point(s), I can take the difference between the WM-2 and WM-3 and add to the specified offset.

Rear rim is a WM-3, again need to establish reference points.

Many thanks for your consideration.

Bill.

All the ones I have done, I initially laced up on the bench. Tightened just a little, and did the final tightening and truing on the bike. I think the measurements are a starting point. The best is to do it where it will live. I did my front disc hub to spec, put it on the bike and it just hit the slider.

The hub to rotor clearance/alignment is set by the factory spacers so only thing to 'offset' is the rim-tire centered in forks or to rear spine so i do like Brad says on the bike so no error or measurement messing-guessing. On the front disc rim you have to almost finish tightening the rotor spokes side before beginning tightening on the other side > to pull the rim back to center and create rotor spoke tension to match.

I did lace my rear Wheel (1974 mk2a) in the swingarm .
Reference point the shock absorbers . VM3 rim . This will center the rim to the frame .
Will do the front Wheel mounted in the fork , reference point the slider .

Michael

RoadScholar,

I called Buchanan's and got my offsets from them. They will give you numbers from the center of rim to a set point on the hub. I have discs on both ends so my numbers came from the disc mount. I trued the rims and mounted them on my bike. I centered my front using the fork tubes (not sliders) as a reference. I think they were with a mm of what Buchanan's recommendations were. On the rear I first checked to see how straight my rear hoops were in relationship to the rest of the bike. I did this by using a laser locating the center of yoke and down the center of the back bone checking to see if that was the center of the hoops. Since everything lined up correctly I simply dropped two plumb bobs, one over each hoop directly in line with the rear axle. From there I just centered the rim off the string lines. Make sure your frame is level left to right and you swing arm matches the frame. Also make sure you rear wheel is not cocked in the swing arm. Good luck.

Pete

I first checked to see that the existing wheels were in the correct spot,(they were) then removed the wheels and placed a straightedge across the hubs to get the offset amount, rim edge to hub edge. I then subtracted for the wm2 to wm3 change and laced the new wheels starting on the bench for intial spoke placing, then moving to the axle clamped in a vise for trueing and tensioning. I set the wheel up with two dial gauges perpendicular to each other for this, but used the straight edge initially to get the offset correct.

When the new wheels were installed on the bike they sat in the correct location, +- about 1mm.

Glen

I got my number from Buchanan's, they are friendly. I recall their numbers are from the center of the rim. I little math is required to determine the point of offset from the rim edge to be able to employ a straight edge for simplicity. I found their numbers to be spot on.

Hi, I know it may not answer really to your search , but may be it could help a bit........

http://www.rgmnorton.co.uk/csi/1245184/ ... ffsets.pdf

This is what I use, measured from a rusty but original '72 Combat

Wheel rim Offset:
Front Disc with WM2x19 rim: 11.75mm on disc side, 22.5 on plain side
Rear (Drum)with WM2x19 rim: Flush with hub on Drive Side
So if you factor in the difference with the WM3 rim you'll be OK

Thanks folks. As much as I like lacing and truing I really was (am) dreading doing the Norton wheels, imagining it to be a subset of rocket science or some kind of black art.

Some excellent replies.

I gather that the bottom line is how the rims conform to the center line when they are in the chassis, but I like to idea that the truing can be done to a repeatable spec off the motorcycle. My son has a set of wheels from the factory, presumably, so I plan to get the measurements off those and see how they jib with some of the responses on this forum and with other sources.

Thanks also for the Buchanan lead, I am one of their dealers and it would never have occurred to me to ask them, fearing I was asking for a chunk of their bread-n-butter. I think more than anything my confidence needed a shot-in-the-arm, super thanks for that!!

Bill.

Whenever I've spoked wheels they have usually centred up fairly well with the nipples finger tight, if there is a specified off set I usually measure half of it from the fork leg or a spot on the swing arm, and pull the rim over that much, check and then do a final. If the offset is wrong, when you align the wheels with a string line, you will find the problem and can adjust. I usually have spacers on the front and back axles which allows adjustment for wheels that have been spoked up for a long time.

if you have the original wheels , before you cut the spokes out take accurate measurements

front wheel use the face of the disc to place your straight edge and measure to the rim edge

Rear wheel measure either from the sprocket face or the hub face where the sprocket mounts