Has anyone come across a cheap and easy way of measuring castor?

i did mine by letting the upper bone drop down to the lower bone, and then measuring in mm the difference from b/j centres. Then measure the height of the hub and do the trig. Or just believe the people who say it boils down to 21mm. I think it was 21 anyway, that or 25...!

I made it 22mm!!

I think MK say 21mm, Thats what I made mine (well tried to)

Mark

MK is for Sierra uprights, mine are Cortina

i was gonna say last night i was on about sierra hubs! mine are about 25 anyway, more the merrier unless the wheels fall off...

Is there no castor offset to consider built into the Sierra hub then ?

not sure about built in castor, but the hub axis is infront of the line between upper and lower pivots, this could be called anti-trail? i think....

this might explain why sierra hubs dont seem to like self-centering much.

any thoughts?