OldBike876

Hello,

I am building a front wheel as a project and have a question about dishing it. I have worked on wheels before, but never built one from scratch.

It's a 700c aluminum rim, a basic Shimano hub, 32h, laced 3-cross. The disc brakes are centre-lock style. So far, I have wheel laced and it's laterally and radially true (although not done).

I plan to dish it by resting the rim on flat boards and measuring the distance from hub to the bench, flip it, and do the same. Is there a "default" amount of offset the brake disc? Have I misconceived what I am doing? Do I want the hub ends equi-distant from the bench, or should they differ somehow to account for the brake rotor?

I appreciate any advice.

Kontact 

The rim should be centered over the ends of the hub (except some Cannondales). If you have trued the wheel, you have everything you need to dish the wheel - just flip it over in your truing apparatus and not the difference between its old lateral position and this one. Dish it, then flip again to check that you found center.

This will be more accurate than the measuring method and you can start dishing immediately after observing the dish.

OldBike876

I think I have it. Thanks. So, one side might have higher tension to account for the brake, but the rim still needs to be on centre.

Much appreciated.

Camilo

You might try building a simpe dishing tool. I did one similar to this:

There are many options and all are pretty simple. Do a search to see if there's one you like.

Ironically, after using my tool on exactly one wheel, a couple of months later I got a real Park dishing tool on the freebie table at the local bike swap. It's really not any easier to use or more accurate. But it's not as clunky to store.

Kontact 

Correct.

squirtdad

slightly off topic....but do spoke calculations call for different size spokes for the front dish, like they do for rear wheels or it the amount of dish so slight that is not needed?

KCT1986

For many of the front disc hubs, there is still enough of a dish that a shorter length is needed for the left side. There are a few different varieties of hubs, (OLD 100/110/etc., disc mount types, flange diameters) so it's hard to generalize.
For most road Shimano hubs, the dish is large enough to have a difference of spoke length in the 1.5 - 2mm between the left and right. It all depends on the individual hub and crossing pattern. The hub specs need to be checked and run through a spoke calc.

OldBike876

I had a devil of a time getting various spoke length calculators to give consistent results. I eventually figured it out and used only one length of spoke.

The dishing is done, i REALLY overthought what a pita that would be.