Extending the seat

[Robert Stewart]

In my ongoing search for Silvio perfection, I have for some time wanted to fit a tail box on my bike (for luggage transport and streamlining). See this thread. Unfortunately, my search for a compatible commercial product has failed thus far. The major problems seem to be the position of the rear brakes and a lack of vertical extension of the top of the Silvio seat.

I am wondering now if it might be possible to bolt on a vertical extension to the silvio seat to make more room for a tail box. What do you think? A crazy idea? Any opinions and/or suggestions appreciated.

Cheers,
Rob

 

[Mark B]

I'd say as far as streamlining goes, you could probably craft something from Coroplast. If I was the kind to get fussy about such things, I would go with something more in line with a tailsock. You only need three points of connection; seat back and off the axles. Some nice, lightweight fiberglass poles and a piece of spandex cut and sewn into shape. I don't think this would gain you the luggage room you are looking for.

I've been thinking more along the lines of an underseat midships rack. Something that would bolt to the seatpan and could be easy on and off if you didn't want to cart the rack around on fast weekend rides. I might take my old Silvio carcass to a friend of mine who is a framebuilder and also a bit of a machinist. He said custom bicycle frames are kind of slow right now, he might relish the challenge.

Mark

 

[cycleguy]

I had done this for the purpose of a head rest... I use it over the winter, when on the trainer, but I took it off while riding on the road... Its made from Aluminum stock I bought at Home Depot. I bent the angle in a vise. Then just drilled holes through seat and bolted it on...

Harold

 

[Robert Stewart]

cycleguy wrote: I had done this for the purpose of a head rest... I use it over the winter, when on the trainer, but I took it off while riding on the road... Its made from Aluminum stock I bought at Home Depot. I bent the angle in a vise. Then just drilled holes through seat and bolted it on...

Harold

Thanks Harold. I had a vague feeling someone had posted details of a home-brewed headrest, but couldn't find the original source before I started this thread.

Cheers,
Rob

 

[John Tolhurst]

Mark B wrote: something more in line with a tailsock

The rebate angle needs to be about 6 degrees, a tail sock is much sharper. A tail sock also has fluttering sides, which spoils laminar flow. The tailbox probably needs to be cut off to make Kamm tail. http://en.wikipedia.org/wiki/Kammback Using cloth, the Kamm tail won't work if there is not laminar flow

I've seen good results (not attached to Silvio) of a Kamm tail with the area of the cut off about 1/3rd the area of the rider's back, and with the side length about 2' or 600mm. This gives a rebate angle of 12 deg, about.

Coroplast always look like a year 10 project. That's the plastic version of corrugated cardboard, right? Try 1mm polycarbonate and you can at least get nice curves in one plane. Try thermo plastic in small sections for where doubly curved surfaces are needed.

 

[Mark B]

johntolhurst wrote: The rebate angle needs to be about 6 degrees, a tail sock is much sharper.

That sailed clean over my head.

johntolhurst wrote: A tail sock also has fluttering sides, which spoils laminar flow.

Can't argue that fact, but if stretched taut enough and you use a quality grade cloth, this can be kept to a minimum. I think the theory being trying to keep as much of the air coming off your body from going into the wheel. In which case, anything is better than nothing.

johntolhurst wrote: Coroplast always look like a year 10 project. That's the plastic version of corrugated cardboard, right?

I agree that a lot of coroplast projects look terrible, but I've also seen some that looked pretty good. Maybe I'm over simplifying, but I think a Silvio would be easy to make something that looked pretty decent. Forgive the crude graphic, but see attached for what I was thinking.