This is another step along the way to getting our daughter’s radio firmly mounted to her Tour Easy, not tucked into one of the panniers. The general idea is to use a water bottle holder for the radio, with a seat wedge pack from an upright bike cushioning the radio. The secret ingredient is a circumferential clamp that mounts the holder to the lower rail of the bike’s seat frame.
This clamp is basically the same as the ones on our bikes, but I doodled up a sketch with some illegible dimensions that almost matches the actual clamp; we may both find it useful the next time.
Machining the clamp is straightforward: bandsaw a block of about the right size, square it up in the mill, helix-mill the clamp hole …
Drill the clearance and tapping holes for the screw, bandsaw it in half, clean up the cut edges …
Obviously, I didn’t put those nice bevels on the front side.
Both previous water bottle holders required a spreader plate between the clamp screws and the holder’s screws, but this time the holder had a nice aluminum plate all by itself. It just fit on the Sherline and a bit of manual CNC center-drilled the curved plate and poked a jobber-length drill through the holes …
And then it fit perfectly on the bike …
A side view …
Now, to find a wedge pack big enough for the HT and small enough to fit in the holder!
The Smell of Molten Projects in the Morning 
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4 responses to “Another Circumferential Seat-Frame Clamp”
Now, to find a wedge pack big enough for the HT and small enough to fit in the holder!
No problem, you can machine foam on the Sherline, right?
Nah, I’d be forced to build a six-axis CNC hot-wire gantry cutter: XYZ UVW. With closed-loop temperature control, of course.
The weird sex-toy seats for upright bikes have really put a dent in the under-seat-pack supply. I looked around at the LBS and didn’t see anything particularly useful: the old two-rail seat with a big cavity under the leather shell is a thing of the past.
Now, my ladies are pretty good with the sewing machines, so perhaps *they* can crank out a custom pack without too much difficulty…
[…] the bike, and … the new aluminum extrusion across top of the plate smacked firmly into the water bottle holder clamped to the rear of the seat frame for the amateur radio. Underseat pack vs radio […]
[…] water bottle holder attaches to the seat base rail with a machined circumferential clamp. Inside the holder, a bike seat wedge pack contains the radio with its GPS+voice interface box and […]