1981 CB750F - Tail Hoop Geometry

jcharny

New Member
I'm trying to decide how long I want the seat to be on my '81 CB750F brat build and thought I'd turn to the group for help. The idea is to weld on a hoop and have a relatively flat seat, with the only curve being derived from the CB750 DOHC's original frame shape. I've looked at some of the other cafe racers in my garage and noticed a general trend- most have the farthest point on the tail hoop just about in line with the edge of the rear sprocket. I've posted a picture of what I mean below. Are there advantages to making it longer or shorter? Primary issues are obviously rear wheel clearance and tail strength/integrity, as I will be riding two-up occasionally.



All advice is appreciated. Thanks y'all.

JMC
 
Looks about right. Keep in mind that how you mount your tail light/plate will effect the lines too. It will look longer once those are mounted. Also, if you go for a completely flat seat pan the rear tire will rub at full compression. You can either limit travel on the stock shocks or make that spot on the fender recessed which will mean less padding in the middle of the passenger spot.

Be sure to post some pics of what you come up with!

A little fender rub on the big hits...
IMAG0508.jpg
 
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