Intro: Front Wheel Drive Recumbent With Underbar Steering
Having previously worked in the bike business I have owned (still own) a number of different bikes. However, one of my favorites was a Vison R40 with short wheelbase and underbar steering. Sadly, when we moved from Florida to West Virginia, we had to sell off the things that didn't pack well into the small moving van we rented, so the Vision found a new home.
My wife has been wanting another recumbent for several years now. However, given the current state of the economy and the lack of a bike employee discount, I was reluctant to go out and spent that kind of money. Then, I read the Instructable for Chuck's no weld recumbent and was inspired.
So, I set out to design my own front wheel drive recumbent, tapping the resources I had on hand.
Step 1: Step One: Find Donors
Since my friends and family know that I have an affinity for bikes, they are constantly gifting me with old bikes and parts. Out of the small cache of bikes I found 2 likely donors. The first was a Canadian version of the Schwinn Stingray made by CCM and the other was a GT Dyno freestyle bike (similar to the ones pictured here).
I chose the CCM as the main platform primarily because it was a mixte frame. A mixte frame is essentially a regular frame, but with two smaller top tubes. In addition to being free, but it is a bit stronger than a normal frame, plus the arrangement of the top tubes gave me a platform for the seat, as you'll see.
Step 2: Step Two: Demolition Man
This is probably the hardest part - trying to decide where to cut and where not to cut. I used a reciprocal saw to make the big cuts and a air grinder to clean up the excess. I cut out the seat tube and bottom bracket off the mixte frame. I also butchered the GT by first severing the rear triangle from the front, then cutting away the seat stays leaving only the seat tube and the chain stays attached to the bottom bracket.
You'll have to use your imagination as I don't really have any pictures of this part.
Step 3: Step Three: Weld and Weld Again
Before I started this project, I had never welded in my life. I had planned on asking my buddy to do the welding, but he declined as his previous attempts to weld a bike frame resulted in disaster. So, after much deliberation, I broke down an bought a $50 oxygen torch from Lowes and set to teaching myself how to braze weld.
There was a lot of trial and error involved. (Or I should say a lot of error and trials.) The three basic rules I learned were: 1) prep and clean THOROUGHLY before attempting a weld, 2) use the right flux, and 3) consistent heat. I attempted to use a separate flux paste and a borax mix that I found on a welding site, but wound up having the best results using flux coated rods. Your experience may vary.
Using a piece of the seat tube I had cut out, I created a 'bridge' from the rear stays to the down tube to replace where the bottom bracket had been cut out. On the front triangle I added bolts on the dropouts to which the fork would be mounted, a new brake bridge, and brazed the seat post into the seat tube once I measured and measured again to be sure.
Once complete, I filed off the excess to smooth it down for painting.
Step 4: Step Four: Underbar Steering
I wanted to figure out a way to make the bike steerable with under bar steering. Other bikes I had ridden in the past had a semi-complex mechanism which involved a second 'head tube' with a tie rod up to the fork. I didn't want to incorporate that much complexity into my design so I opted to install a handlebar stem through the bottom of the fork.
Since the fork's inner diameter at the bottom is smaller than at the top I decided to grind/sand/file down the stem itself to reduce it enough to fit. The fit was still very tight and I had to drive it in using heat and a dead blow hammer. Using a 10"x3/8" carriage bolt down though the seat post and fork was used to both marry the front triangle to the rear, but also to securely fasten the stem in place.
I settled on a set of beach cruiser bars (pictured later) which provided sufficient reach and leverage.
Step 5: Step Five: Painting
I don't have any action shots here, but it is a necessary step.
I started by cleaning and smoothing down the metal with a flat file, followed by 400 grit sandpaper. I eventually moved to 000 steel wool before applying 2 coats of primer, using 800 grit wet sanding between coats.
I then applied 2 coats of Krylon, again wet sanding between and finished it up with 2 coats of clear using 1500 grit wet sanding between and on the last coat. Then I buffed it all to a shine.
This is the longest step and requires the most attention to detail. Patience is a virtue.
Step 6: Step Six: Making the Seat
To get the right shape, I started by tracing an outline my wife's torso. Based on other designs I've seen, I then modified the outline to provide support where it is most needed. I transferred the pattern to a sheet of 3/8" plywood I had in my scraps and cut it out using a jig saw. Then I cut it into 2 pieces to create a seat and back. I then added hinges to allow the seat to recline.
In the base of the seat, I drilled slotted holes for 1/4"x2 1/2" carriage bolts which would be used to mount the seat to the frame. The slots allow the bolts to be adjusted left and right to accommodate for the seat tubes. On the back of the seat I also drilled a hole for a 1/4"x2" carriage bolt for the bracket which would be used mounting the new seat stays.
Next, I bought some dense foam rubber mats from the flooring section in Lowes. It ran about $17 for a package of four 24"x24"x3/8" pieces - enough to make about 2 seats. I cut the foam to roughly to the shape of the plywood pieces and glued them to the plywood with rubber cement. Then I added a second layer by the same process. Using a 5" sanding disk attached to my drill and 150 grit sandpaper, I shaped the foam rubber to create a slight lumbar support and cupped areas for the upper back and buttocks.
To cover the seat I used 2 pairs of 'fat lady', black, winter tights. I cut the legs off and worked them on starting from the top. After I had added all four layers, I simply pulled them around over the front and stapled it to the bottom of the seat. If I did it again (and I'll likely have to), I'd use cotton tights or something similar. Even though the material is pretty tough (and considering who they're designed for, they'd have to be) they have already started to develop runs.
The entire assembly was mounted to the frame using 5/8" adel (rubber lined) clamps around the top tubes, then a 1/2" nylon spacer, and a fancy wing-nut. The spacer simply provides room for the nut to turn. The pictures provide the best details.
The rear mounting bracket was actually fashioned from a swingset clamp. I drilled three holes - one to bolt it to the seat and the other two for mounting the seat stays. The seat stays are simply 24" pieces of 1/2" conduit that has been squashed to an oval shape on the end that mounts to the seat bracket, with a 1/4" hole drilled about 3/8"" from the end of the tubing.
To mount the stays to the bike, I originally attempted to use adel clamps using a setup similar to that which was used for the seat bottom (1st picture). However, I found that under load the clamps had a tendency to slip no matter how much I tightened them and though I had originally intended to use the old sissy bar from the CCM bike it proved unstable. I decided to instead drill a series of 1/4" holes spaced 1" apart. A 1/4"x2 1/2" carriage bolt is inserted though the rear dropout followed by a 1/2" nylon spacer, the seat stay, and finally a wing-nut to hold the entire assembly in place.
Step 7: Step Seven: Final Assembly
Though I won't go into the details of actual bike assembly, I will show the issues and pitfalls that I encountered with this particular project.
To begin, I didn't do a 'dry fit' of the bike prior to welding. This error became most clear when installing the crankset and front brake. The new brake bridge I welded into the front triangle is in a very tight spot. As you can see in the pictures (2nd photo), the brake is very close to the chain line, though it does not interfere with the operation. However, on the non-drive side the crank arm tapped against the brake arm. I tried different ways to correct the problem, but wound up filing down the brake arm slightly, enough to give it a few millimeters of clearance (3rd photo).
One of the things that turned out right was the addition of cable routing. During the welding phase I bought some steel spacers, cut them down to about 3/8" long and brazed them along the down tube, fork, and chain stay to allow the brake cables to be routed and keep them from interfering with the operation of the bike.
Step 8: Step Eight: the Ride
I haven't taken it out for a spin, yet. Just sitting on it, it feels pretty stable. I'm planning on taking it out this weekend to make sure everything functions prior to handing it over to my wife.
This is currently a single speed. I wanted to keep the budget low for now. Once my wife takes it for a spin and decides whether or not my efforts were worthwhile, I'll look at installing a 3 or 5 speed hub to give her a little more flexibility.