Wednesday, February 28, 2007

Oh My Aching Seat

So my new seat is installed, and the cover has been laced on. That went pretty well, although I noticed one flaw. The two grommets at the cutouts for the crosspiece are located on the edge of the upright tubes. Since the grommets are flat and the tubes are round, they are starting to tear out. I don't really need the tension right there, so I think I'll cure it by relacing the seatback and just skipping those holes. The grommets at the top of the back and the front edge of the bottom are ok, maybe because there isn't so much strain on them, but the middle ones won't work.

I took a ride around the block, and decided I like my new seat (I can reach the ground now), but the curve in bottom toward the takes away my "bun space". I kept sliding down, and couldn't stay in one place. So, a recurved design is needed for the bottom part of the seat. Maybe I'll just have the tubes come straight back to meet the seatback at an angle, instead of curving them up. The front part of the seatbottom is perfect.

I swiveled the steering riser tube around to bring the handlebars back about three inches, since the seat leans back slightly more than it did before. I don't think I like that - I lost some of the responsive feel the steering had. I'll be changing that back.

I was having trouble getting the chain to shift gears properly without throwing it off either side, so I installed a disc on the outside of the front gears, and a small stop on the inside. I could not get a point of adjustment that would give a slow reliable shift without throwing the chain in a quick shift. I think it might have to do with the fact that the middle gear was not intended to have a smaller gear, and it actually sort of tilts inwards at the top of the teeth (if that makes sense). Anyway, problem solved, even when shifting while going over big bumps.

More changes, more test rides, more fiddling, more tinkering.



Wednesday, February 21, 2007

Seat Cover

More Pictures. The top one shows the fabric after I cut it out. I applied wide masking tape wherever I needed to make a mark and laid everything out using a pencil and a yard stick. Then I laid the fabric over the frame to make sure I had the cutouts in the right place, and to think through the seam corners so I wouldn't mess it up. Then I made the cuts.

The second picture shows the two sewn/grommeted pieces laying on the frame. The cutouts are where the cross pieces underneath are welded on. They actually line up this time. I made the 2" top and bottom seams first, then the cutouts, and finally the 1" side seams. I used 1/4" grommets again (more on the bottom, less on the sides). The third picture is a closeup of a cutout.

The Recumbent Blog had an entry today for the Greenspeed Frog (trike). I'm thinking of building a trike next, so I was excited to check it out. The website the link took me to is like a candy store. There is a link on the left side (Builders Corner), that has more homebuilt bike pictures than I've ever seen. And the pictures show all kinds of stuff, from CAD drawings of concept bikes to "how I attached three headlights". Of course the text is in Dutch(?), but a picture is worth a thousand words to a visual learner like me.



Monday, February 12, 2007

Seat Frame Again

I apologize for not writing much lately. There haven't been many things worth mentioning, at least not that I feel like sharing. I guess I haven't been feeling very wordy.

Here are some more pictures. I made the new seat frame this weekend. It will lay back a little more, sit further forward, and have less of a "thigh shelf". It's quite a bit norrower, a decision I really hope I don't regret. I cut off the idler pulley mount, reinstalled it closer to the frame and made a clip to keep the chain from bouncing off when I go over big bumps.

I rode around a bunch Saturday hopping off curbs, going in tight circles, and just getting used to the feel of things. I'm going to develop some serious thigh muscles on this thing. I was surprised at just how little shifting I needed to do riding around the neighborhood. I could still pedal productively up a small hill in the same gear I used to come down it. Shucks, on my Schwinn I'd have shifted through the entire range going both ways. Maybe the Schwinn is just too easy to shift, and too hard to pedal.



Friday, February 02, 2007


The Community Cycling Center is one of Portland's coolest places. Their goal is to get a bike to every kid - regardless of whether or not they can afford it. They do this through donations of used bicycles and lots of volunteer labor refurbishing bikes. They hold cheap/free classes in bike maintenance, sponsor rides and help kids learn to be responsible riders.

They also sell parts to maintain your bike. Enter: new shifters for my recumbent! I picked up a matched pair of Suntour ratcheting shifters for a pretty fair price (more than I wanted to spend, but cheap for such a nice set of levers - I couldn't pass them up).



Thursday, February 01, 2007


I finished the chainring modification. I welded some little spacers on the backside of the middle ring, then clamped the small ring to the front side and drilled through the whole stack at once. Then I moved the small ring to the backside and riveted it in place.

After primer, flat black paint, and reassembly I realized that I needed to rock the shifter back just a little more so it would have enough range to cover the difference in sizes of gears. So I heated the tube with a propane torch, stuck a larger drift (punch) inside the tube and used a cargo strap to winch it rearward, so the shifter dropped a little lower. It was a crude operation, but since I planned it well, and measured carefully, things went smoothly. I can't wait to ride it again. Just a few more changes first.