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Re: Aiming headlights WAS: Headlight heat and power draw

In your message regarding Re: Aiming headlights WAS: Headlight heat and
power draw dated Wed, 13 Dec 2000 12:57:19 -0500 (est), William A. Flowers
said that ...

>WAF-  Previously, you (Mike Bostock) wrote:
> > I may be missing something here but wouldn't this mean that the beam was
> > *parallel* to the ground which surely can't be right??
>WAF-  Only the top edge of the beam would be parallel to the ground if done
>WAF-  that way.  However since the beam spreads both up/down as well as
>WAF-  left/right you'll find that the headlights (headlamps) are aimed
>WAF-  downward.

Not wishing to be pedantic here .... but really the beam should be aimed
downward IMHO and probably the opinion of Department of Transport in the
UK :-(.  SO if the top edge of the beam should strike the (perfectly
level) road at say 50 metres ahead of the vehicle then the beam needs to
be angled downwards at an angle of 1.00830161752564402676764392207397
degrees if the height of the centre of the headlight is 0.88 metres (as it
seems to be on my Sprint - just been and measured it with a not
particularly accurate tape measure so don't quote me on this). This of
course is variable according to the amount of compression on the front
forks.  Now given these basic parameters then at 1 metre from the garage
door (on your perfectly level surface) the top edge of the beam should be
86.24 mm and at 5 metres should be 79.2 mm.  These are only rough
'ball-park' calculations you understand.

> > BTW then when a 16
> > stone rider sits on the saddle the beam will then be pointing upwards due
> > to the compression of the rear suspension.
>WAF-  Hopefully your front suspension compressed some also.
>WAF-  I'd want to do the alignment with me sitting on the bike for just the
>WAF-  above reason.  That makes it a two-person job I'd guess.  As soon as I
>WAF-  can figure out where to locate 25+ feet of level ground facing a wall.

What about a pillion - oh well I'll have to get back to the calculator for

How much do you say the suspension should compress.

:-) :-) :-)

I need to get a life

- -- 
Mike Bostock

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