LINKS TO SOME OF MY OTHER STUFF
Sunday, May 18, 2008
HOW TO BUILD AN INEXPENSIVE SUSPENSION RECUMBENT BICYCLE AT HOME PART 4
Now that the seat is installed, it's time for the job that will rack your brain big time: chain management. On regular bikes this is pretty obvious, the chain goes straight from the chainring sitting in front of the rear wheel not too far ahead.
In our case, the chain has to make a few detours to get from the chainring to the rear wheel and must avoid a whole bunch of things on it's way there and back. Before you start making your chain management set up, make sure you install everything on the bike, brakes, cables and every little doodad that goes on there. You must know what will be in the way of the chain before you install it. Remember, we're not working with plans here! One of the easiest ways to bring the chain from the rear to the front is with black PVC type tubing. I use the kind that is put in the ground for lawn sprinkler systems. 100 feet for $12, it should last you a lifetime. Those types of tubes usually last one season, so all the extra is not for nothing. It is surprisingly quite, you just have to make sure you secure the tubing with a good amount of duct tape strategically placed so the tube doesn't move with time. Leave the very front and back of the tube loose so that the chain can move when shifting from one gear to another.
That takes care of the top part of the chain, now for the lower part or the return section of the chain. When the chain is moving in the lower section, it isn't under tension and we can get away with less strength in our deviation set up. I use a grinded rollerblade wheel secured at the old bottom bracket by using a front wheel axle jerry rigged on the left bearing cup. It holds pretty nice and is very quite. I allow the wheel some movement on the axle so the chain can remain more straight in its path back to the rear wheel. I also added another wheel which I made from an old printer bracket wheel that I attached to the clip that holds the front boom. I sandwiched an old derailleur wheel on it. I used that one to clear the top of the fork while the chain is on its way back to th rear of the bike. I could have used another rollerblade wheel type of arrangement there as well, but I already had that set up lying around.
Now at this point the bike can be powered. Before you start installing all the accessories and other little knick knacks, install a working rear brake and take it out for a ride to see if your prototype is actually functional. I did with mine and that's when I found out that...
IT'S A TOTAL FLOP!
Yes, sadly this is a possibility when you hodge podge a homebuilt bike together. Before I started this build, I figured there was going to be some flex when pedaling the bike caused by the rear suspension, but I wasn't expecting that much. The thing bounces around like a clown bike when under full pedal power from a dead stop. Climbing hills is just very hard labor and extremely slow. I had tightened up the spring on the cheapo shock absorber, but it wasn't enough.
Mind you, the suspension does its job while going downhill or when you're up to speed on the flats. But unless you want to train to get legs like Lance Armstrong, going on even the slightest incline is murder for your leg muscles. There might be a way to lock the shock when you need it or a better quality shock might work better, but I don't have the time or money right now. I need a working recumbent for a big critical mass event in 2 weeks. Not only does it need to work, it also has to be broken in, no time to do repairs on a big ride like that. So on with:
Plan "B" is my previous short wheel base recumbent that my son affectionately called the "Pocket Rocket". It is made from and old CCM mixte frame. It runs on a 20 inch rear wheel and a 16 inch front wheel. I had some elements like the front boom and brake bosses welded on by a welder for hire. Cost of the welds back then came to about $20. Next post will be about slapping the Rocket back together. Sorry about this let down, but things like these happen when you make stuff yourself from junk. Remember that practice makes perfect.
Til next time, ride safe and Godspeed.
Homebuilt recumbent part 1
Homebuilt recumbent part 2
Homebuilt recumbent part 3