It originated in the Long Distance riding community. Where stock was never good enough. People were bolting HID ballasts to their windscreens, just because that was the only place they could fit the huge, early ones. New brake pads are not a farkle, but wave rotors might be. Custom fabricated fuel cell, most definitely. Hydration system made of a dog dish, some food grade tubing from the hardware store, a bite valve and an old Coleman 1 gallon jug, you better believe it.
The idea originated in finding solutions to problems the average day rider never had. Stock seat is comfortable... sure, for a few hours. Not 20 hours a day for 11 days. Different solutions for different needs and different people. Some farkles you can't wait to try on your bike, others are, well... interesting. Like the funnel and pee tube out the back of the bike. Yeah, I'll just stop and pee, thanks. OTOH, Dude! You must be freaking hung like a mule to actually use that "in flight"! ::025::
