Wheel offset, hub to wheel edge

I am in the process of respoking the front and back wheels, while this doesn't present too much of a problem, the concept of offset relative to wheel edges is confusing to me. Any help anyone can give me would be greatly appreciated. Thanks!

Give us a clue - what year, make and model ?!

Some bikes have the rims laced perfectly centrally on the hubs.
And some bikes have the rim offset slightly to one side of the hub.

This can be say on the back wheel, where the sprocket complicates things and they moved the rim, by design, slightly over -
- so the sprockets line up AND the rim is still in the centre of the bike.
Or the front wheel of a Commando with disk brake, where the disk interferes with the spokes.
So they moved the hub to one side, and laced the spokes more vertically on one side, to keep the rim on the centreline of the bike.

You can either measure the rim offset BEFORE unlacing the wheel.
Or keep lacing the rims by trial and error, until the hub is in the right place and the rim is still central to the bike.
Measuring it first is the easiest, but lots of folks go the 2nd way, when something is not right at the 1st try !
Hopethishelps.

The concept of working from one side of a rim leads to errors.Not all rims are exactly equal width.Measure any rim and the width will vary at different points around the circumference.
The front rim must be central in the forks;dead centre.
The rear rim doesn't need to be central to the frame,but it should be close.It's often better if it's not dead centre.Depending on what bike you have,how far is the gearbox sprocket centreline from the frame centreline?A Triumph twin is 3".A Manx Norton is 2-7/8".

You could set the rear rim up the same,so the sprocket centreline is 3" (or whatever) from the rim centreline.When the sprockets are aligned,the rim will be central in the frame.It will probably steer itself to the left,because your bike is likely to be heavy on the primary side.In that case shift the rear rim 1/16" toward the primary.It works well on most bikes that have a heavy clutch and alternator on the primary side.

I suggest you should spoke the rim central to the hub, then use string lines to check that you can get the wheels in line in the bike. You might have to pull a rim to one side to get the rim central within the swing arm. So don't cut the spoke tips off too soon. Having the wheels in line is most important, if you don't want your bike to have a heavy feel to it.

Just a suggestion, the wheels should be centered to the frame. Get a construction laser which puts a plane of light onto the backbone of the frame. Assuming the backbone of the frame is dead centre then the laser line locates the centre of the forks where the centre of rim is to be located. This procedure is simpler than it sounds.
While you are at take off the rear fender and you can check the alignment of the rear wheel. It is such a joy to go down the road with front and back wheel in perfect alignment.
Cheers

I don't think you will be able to change the offset drastically even to suit a bent bike.
I did a dry run on a Madass rim last night.

I've sometimes had to machine spacers to move the rear wheel across and then turned it to get alignment . If you loop a string around the front of the front tyre, under the bike, around the back of the rear wheel, and the back under the bike to the front, you can align the wheels quite well by turning the forks, and adjusting the position and horizontal rotation of the rear wheel. You might need a couple of matchboxes at the back of the rear wheel (against the rim) to space the string clear of the front of the rear tyre. By 'looping the string', I mean once around the whole tyre and rim.
This exercise is something t hat a lot of racers forget to do, and it is important.

Mk2a 850 wheels.
The front is a (nice) aftermarket rim with stainless steel 8 ga spokes and 0.300" nipples but I picked up a NOS MC275 rim to replace it
The rear is a stock rim and stock 8/10 gauge spokes with 0.251 " nipples.
The odd thing is the MC275 is drilled for 0.300" nipples.
Can anyone confirm that the 850 had different sized spokes and nipples front to rear ?

Buchanan's say for the front disc wheel.

Stock spokes were 8 ga. with .300" diameter nipples.

Click to expand...

but their spoke kit has 0.281" nipples.

For the drum hubs.

Although the hubs do not interchange front to rear, the rims and spoke kits do. Hub measures
9" diameter and 2 1/4" wide. Stock spokes were 8-10 ga. with either .250" or .300" dia. nipples.

Click to expand...

http://www.buchananspokes.net/products/ ... norton.asp

It just seems a bit odd unless it has something to do with the disc wheel coming later and having a large offset,perhaps that is the reason for increasing the spoke and nipple size.
I was thinking it was going to be a simple case of either getting a stainless set for the rear or even stock galvanized for the front.

Spoke Gauges are as follows:
12 = 2.60mm (.104” dia)
10 = 3.20mm (.124” dia)
9 = 3.60mm (.142” dia)
8 = 4.00mm (.156” dia)
7 = 4.45mm (.171” dia)
6 = 4.87mm (.192” dia)
5 = 5.15mm (.203” dia)
4 = 5.70mm (.224” dia)

Click to expand...

the front has 40 .300" nipples
the spokes are 8G on the disc side and 9G on the other side
The rear has 40 .250" nipples and 10G spokes