Wheel lacing - help

Finished product. Rebuilding and cleaning front forks before on to the rear rim.

Looks good!
Have you attached the rotor and mounted the wheel, to see if the disc is centered in the caliper? That's the test of truth, I reckon...

the rotor should always centre in the caliper

the critical test is weather the rim centres in the fork legs rim to hub offset is the important bit to get right

I have not remounted the rim as I have both forks apart cleaning and rebuilding them. I will say that the rim runs less than 10 thou out on the truing stand. There was no hop during rotation. I've measured the hub to rim and have the general consensus measurements of 22 and 11 mm in place. Entirely possible I've missed something but will watch it again once the bike starts going back together.

Mr. Rick said:

Looks good!
Have you attached the rotor and mounted the wheel, to see if the disc is centered in the caliper? That's the test of truth, I reckon...

Click to expand...

the disc mounts directly to the hub, and the spacers on the axle and whether or not the caliper is shimmed determine whether or not the disc aligns. The rim has nothing to do with disc alignment.

The caliper is shimmed? I musta missed that during the the assembly of my own front wheel. And in the parts list.

"The rim has nothing to do with disc alignment."
Nothing at all, until you actually assemble them and find that the rim is fixed to the hub and the hub is bolted to the disc, and that HOW you assembled them determines whether or not the disc centers in the caliper when you're done.
I can see how one might be able to (not that I'd want to) use shims to move the caliper leftward in a pinch. What do you do if you need to move it to the right?


"the critical test is weather the rim centres in the fork legs".
This surprised me, so I checked and found that my rim is not even close to being centered in the fork legs.
The rim clears the left fender mount by about 0.90", the right by about 1.20"
I'm interested now, to know what others are finding, and why it would matter?

Mr. Rick said:

The caliper is shimmed? I musta missed that during the the assembly of my own front wheel. And in the parts list.

Click to expand...

You are right, there are none (that I am aware of) for the stock brake. I have a CNW Brembo kit, and it uses shims to align (if necessary - it wasnt in my case).

Mr. Rick said:

"The rim has nothing to do with disc alignment."
Nothing at all, until you actually assemble them and find that the rim is fixed to the hub and the hub is bolted to the disc, and that HOW you assembled them determines whether or not the disc centers in the caliper when you're done.
I can see how one might be able to (not that I'd want to) use shims to move the caliper leftward in a pinch. What do you do if you need to move it to the right?

Click to expand...

This is not a Rim/offset problem - this is a hub assembly problem. Dont mix them up, as they have different causes/effects as you point out.

Mr. Rick said:

"the critical test is weather the rim centres in the fork legs".
This surprised me, so I checked and found that my rim is not even close to being centered in the fork legs.
The rim clears the left fender mount by about 0.90", the right by about 1.20"
I'm interested now, to know what others are finding, and why it would matter?

Click to expand...

gortnipper said:

Got the rear fender and tail light assembly on, with much fettling.

Got the front wheel on and the caliper shimmed correctly.

But, the fender stay was rubbing on the tire on the primary side. 8mm clearance on the other side at the bead. My first thought was maybe the fender stay was flopped and needed tweaking.

But it looks like the wheel is laced 2.5mm dished too far to the primary side.

I suppose it will need to be retrued to center it properly.

Click to expand...

I had the wheel re-laced and moved 2.5mm over to the disc side. Centred perfectly between the forks now, and the disc is still centred as well.

It looks like you have fitted a wider rim than stock

if the rim you fit is say 5mm wider overall you have to take 2.5mm off the offset measurement to get the correct hub / rim offset this in theory should then align correctly with the forks

i did note a comment regarding why does the rim need to be central of the fork legs ? the fork tubes / stanchions are of equal spacing from the head stock centre line and the centre line of the chassis

so take the centre line measurement between the stanchions with wheel spindle loose in clamp and not nutted up and mudguard off ( fender brackets can often pull the tubes together )
this measurement should be centre of the rim

Mr. Rick said:

"The rim has nothing to do with disc alignment."
Nothing at all, until you actually assemble them and find that the rim is fixed to the hub and the hub is bolted to the disc, and that HOW you assembled them determines whether or not the disc centers in the caliper when you're done.

Click to expand...

The bearings, spacers and spindle/axle determine the position of the hub and therefore the disc so the hub and disc should remain in the same position.

Mr. Rick said:

"the critical test is weather the rim centres in the fork legs".
This surprised me, so I checked and found that my rim is not even close to being centered in the fork legs.
The rim clears the left fender mount by about 0.90", the right by about 1.20"

Click to expand...

The rim offset is off (by 0.15") and the usual method to correct that is by altering the the rim offset relative to the hub, not by adjusting the hub position.

Mr. Rick said:

I'm interested now, to know what others are finding, and why it would matter?

Click to expand...

Ideally, for best handling, the centre of the rim should align with the steering axis so usually centred between the forks.

FWIW
If you make adjustment to your rim it might be wise to remove the tire and see if any of the spoke ends are sticking out past the nipples when you are done. Very nice job by the way.
Pete

Frankie17 said:

It looks like you have fitted a wider rim than stock

if the rim you fit is say 5mm wider overall you have to take 2.5mm off the offset measurement to get the correct hub / rim offset this in theory should then align correctly with the forks

Click to expand...

I fit a WM3 rim, which the builder provided. He screwed up on the offset. I provided this info partially to illustrate a change in offset does not change disc alignment.

Thaks to gortnipper, Frankie17, and as usual, to L.A B., for helping me "get it straight"
Being bolted together, the disc of course cannot move relative to the hub, and should stay centered in the caliper, whatever the offset may be.
I think I fooled myself thinking it was possible, when I used the disc, rather than the hub, to measure offset. The rotor being so much wider than the hub, and nice and flat, it made my assembly easier to use the disc as a reference for the rim position.
Now it seems that I didn't do such a great job after all, with the rim off center to the yoke/fork tubes. Too bad I got it incorrect to the off side (wrong to the right?). It looks like it wd be much easier to pull the rim to the left, using the non-disc spokes, than it will be pulling the rim to the right. Now where did I put that dial indicator? :roll:

Now where did I put that dial indicator? :roll:[/quote]

My indicator has a large "button" adapter that I applied a couple layers of masking tape too. This prevented scratches on the finished side if you have aluminum rims. I think it is possible to set an indicator to ride on the inside of the rim lip where the tire sits for the same reason.

Pete