Re: Latest projects

[Ben Barkow <dr.ben@xxxxxxxxx>]

>> For deceleration (as in engine braking before hitting the brakes), I
>> tried mercury switches (like in old thermostats) and weighted
>> microswitches (you can set them for precisely .5 g by a simple
>> strategy) but both methods gave more false alarms on bumps than
>> helped with engine braking. Next I am going to try a vacuum switch
>> set to maybe 15 in/Hg.
>
> Dr. Ben,
>
> I've ridden behind riders with similar deceleration/engine-braking
> lights... It was damn annoying to see brake lights come on as they
> approached every... turn... on.. the... road...
>
> I understand the motivation, but question the utility. I note that
> the brake light(s) (I have red LEDs in my turnsignals that come one
> with the 1157 bulb in the tail light) on my GS come one before the
> brakes grab their disks, so I can effectively signal drivers (or
> other followers) to back off without necessarily slowing down.
>
> - --
> - - Andrew, Berkeley, '00 R1150GS
> - - "Moto per Mangiare, Mangiare per Moto"

Thanks Andrew, you are quite right that false or excessive alarms are a  
great nuisance - and to my mind that includes all kinds of assertive  
brute-force conspicuity measures which are harmful to other road users  
because they selfishly distract them in your direction. Not to mention  
needlessly bright headlights.

But for a liter-bike, coming to a plain ordinary stop sign is based on  
engine braking until the last few feet, even if you are not a big  
downshifter. I ask you to observe this yourself and to note other times  
when you are strongly decelerating before touching the brakes per se.  
Olde riders habitually do a rear-brake tap-dance to communicate slowing  
down to drivers behind.

The automatic manifold vacuum approach very closely correlates with  
deceleration provided that it is set properly. I rode around with a  
mock-up on the dash for a while and was surprised at how very few  
false-positives occurred if set to around 16 inches of Hg and of  
course, it could be set up to maybe 18 inches and work OK. I am an  
aficionado of tuning with dual vacuum gauges and I know that high  
vacuum only occurs during strong engine braking and hardly ever with  
the clutch pulled in.

If you are slowing fast (and engine braking can be quite powerful), you  
ought to let the folks behind know it. When I had a 1960s Alfa (early  
car with 4-wheel disks) we used to joke that you should look in the  
rear view mirror before braking hard.

Picture of dual vacuum gauges temporarily mounted road testing.

http://mail.ica.net/users/barkow@xxxxxxx/Pictures/ 
%20d%20v%2Dg%20mounted%20on%20bike%2084.psd

Ben
warming up in Toronto

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