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socialtalker
08-18-2010, 05:17 AM
one of the last things i have to get is my seating. i dont have a question, exactly, just posting. i am taking that very seriously because my getting on a seat of a regular bike trying to ride it is what started me thinking about building a bike in the first place.

i was just going to get the fishing boat seat for my loderunner like in the plans, however, i knew just looking at it, that i would need a seat that should be strongly braced in the back as i would brake that back in no time.

this being a semi-recumbent bike i believe you call it, i have been having some confusion what kind of seat to make. at first i was going to make a seat with lots of squishy foam and maybe a gel cushion in the center, now i am understanding that is wrong, because it will lose its shape and produce a lot of heat and pressure points. many places including this forum recommend very firm memory foam, okay. i was looking at motorcycle seats, especially this video, the layers of foam look incredibly complicated.

http://www.youtube.com/watch?v=H4rlIcmEl6c

apparently this company makes a thermal imprint of your butt and works around it to make a great seat.
there doesnt even seem to be instruction on the web how to make a seat that will reduce/minimize pressure points in your butt.
anyway i was going to wing it by guessing the right shape and play with, but i have also come across people making fiberglass seats.
http://www.customfighters.com/forums/showthread.php?t=22549

http://www.jeffreyphipps.com/seat_pans.htm
i like this idea, surprisingly. folks are both using the seat un-cushioned or with padding and covered. it can be formed in any shape, doesnt heat up, and i think might be much lighter that using 1/2 inch of flat wood under 5 layers of form and still be strong, i hope. maybe if i put like 9 layers or something. only thing is i am not sure how i would attach to the seat mount. oh well one thing at a time. i am very glad i hadn't got fiberglass fabric yet.

Odd Man Out
08-18-2010, 10:43 AM
point to remember -- pressure points are caused by long term pressure placed on specific points. Motorcyclists are prone to this cause they just sit while cyclists not so much because we are constantly moving while pedalling. There is something called "recumbent butt" but that i believe is caused by a bad seat design -- if your seat feels "right" when you sit on it and you have no problems with bottom bracket height**, you should not have problems with pressure points.

** For some people, having the bottom bracket positioned higher than the level of your gluts causes some problems -- pressure points, numbness and leg strain.

Locutus
08-24-2010, 12:17 PM
I found the basic board/foam seat of the AZ design that I used on my Marauder to give me some discomfort in the tailbone area after riding for a while. So when I built my Street Fox I decided to craft a more ergonomic seat using similar materials (plywood and a foam exercise mat, covered with vinyl coated fabric). The result was a quite comfortable seat that I could ride for hours with no discomfort. The trick was to cut out foam at the pressure points like under the vertebrae and tailbone, and add foam for lumbar support. Here's how I did it:

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes256.jpg?t=1243723506

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes257.jpg?t=1243723597

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes259.jpg?t=1243723832

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes260.jpg?t=1243723901

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes261.jpg?t=1243724043

http://i59.photobucket.com/albums/g292/Locutus59/Workshop/bikes262.jpg?t=1243724126

(The smaller piece is the upper back rest which was later mounted above the seat on an adjustable swingarm.)

socialtalker
09-08-2010, 04:04 AM
thanks for responding. i have never even sat on a motorcycle nor a recumbent. last year when i sat on a upright bicycle for a few minutes, believe me, i felt the pressure points, all of them. lol. i wound up pinching a nerve in my left leg and i was literally walking funny and in great pain for 3 months. literally just being on an upright bike for a few minutes cause it. the loderunner not being an upright nor a full recumbent, i am not sure where the pressure points will be. i hope they will be like a regular chair, so i am planning accordingly.


point to remember -- pressure points are caused by long term pressure placed on specific points. Motorcyclists are prone to this cause they just sit while cyclists not so much because we are constantly moving while pedalling. There is something called "recumbent butt" but that i believe is caused by a bad seat design -- if your seat feels "right" when you sit on it and you have no problems with bottom bracket height**, you should not have problems with pressure points.

** For some people, having the bottom bracket positioned higher than the level of your gluts causes some problems -- pressure points, numbness and leg strain.

socialtalker
09-08-2010, 10:14 PM
beautiful job! i was thinking about the ergonomically contouring in fiberglass because i was hoping it would keep its shape. still not quite sure how to contour it properly


I found the basic board/foam seat of the AZ design that I used on my Marauder to give me some discomfort in the tailbone area after riding for a while. So when I built my Street Fox I decided to craft a more ergonomic seat using similar materials (plywood and a foam exercise mat, covered with vinyl coated fabric).
(The smaller piece is the upper back rest which was later mounted above the seat on an adjustable swingarm.)