Wheel offset question

[H]

On Thu, 2 Nov 2006 18:09:50 -0700, Chris Thorp wrote:

>I don't mean to seem argumentative, and I find your advice very  
>helpful, but I'm a bit confused how clearance isn't directly related  
>to offset.

Offset describes the horizontal distance between hub contact surface
and center of *tyre*. Nothing else. The spokes can have any size or
shape without affecting offset. The size and shape of the spokes will,
however, affect caliper clearance.

Imagine turning your wheels inside-out. You'd have extremely low
offset (even positive), but the spokes would still crash into your
calipers.

>If I put on a (hypothetical) 10mm spacer, which would  
>change my positive offset wheel from ET30 to ET20, wouldn't I have  
>exactly 10mm more clearance?

Yes, that's correct. Adding a spacer is one way of changing offset,
but that's not necessarily how the manufacturer did it with your
particular wheel.

The spacer moves the entire wheel outward. If you were to build a new
wheel, you might choose to move the tyre outward on the spokes
instead.

In other words: When you buy new wheels, you must always check caliper
clearance, regardless of wheel size and offset.