September 15, 2013
By Rich King
[EDITOR’S NOTE: Last fall when Bike Friday faced the challenge of our tikit stem recall, Richard King appeared out of nowhere to lend his assistance. An independent engineer with experience in failure analysis and stress analysis, King came up to Eugene at his own expense, and visited Bike Friday.
He reviewed our testing procedures as well as our solution, and gave us valuable independent confirmation that our solution was sound. Shortly after that, Richard became a Bike Friday owner. He recently sent us this note:]
Instead of “what did you do on a Bike Friday,” this post is in its own category: “what did you do to your Friday?
I had a very nice Bike Friday Pocket Companion, minding its own business, serving me well as a travel and utility bike. I used to have a Rans Rocket recumbent, a double 20-inch short wheel base, which was fun to ride. They don’t make it anymore.
I now have a Bacchetta Strada, with bigger wheels and an aerodynamic laid back position. It was fast but not as manueverable as the Rocket had been.
Also ‘bents are not the best to travel with, of course (except for those fortunate enough to own a SatRDay).
I don’t remember when the seed got planted, but it occurred to me that if you removed the seat post on my Companion and put on a recumbent seat, then clamped a boom on the front for the cranks, the Friday’s geometry would be similar to the Rans Rocket’s. By angling the boom a little higher and reclining the seat more, youâ€™d get a more aero position similar to the Bacchetta’s.
I’m not a machinist. I am a mechanical engineer, but a theory guy.
I can analyze things on a computer just fine, but actually working with metal in practice is more of a challenge (to put it kindly). Also the tools at my disposal are the typical suburban garage stuff.
So out came the hacksaw and I cut the boom off the Strada, after she served me faithfully for about 8 years. Sorry! I was able to recycle the steel from her frame and sell some of the components, and reuse the recumbent seat for my project.
I squished the end of the boom in a vice to mimic Friday’s ovalized main tube. I took an aluminum tube and also squished it, cut in half, and used it to splice the boom to the Companion with tube clamps from McMaster-Carr (a good source for general-purpose mechanical stuff).
Some “mending plates” from the hardware store served to improvise a clamp for the bottom of the Strada’s seat. The back support tubes (known in the ‘bent world as “sprint braces” — a bit of exaggeration if I’m the rider) fit nicely into the threaded eyelets Green Gear provides for a rear rack.
To finish it off, I used the Strada’s rollers and chain. “Chain management” is a big issue on recumbents in general. When youâ€™ve got to replace your chain you use three conventional bike chains hooked together. The humongous length of chain flops all over the place and rubs on things if you don’t “manage” it. The x-roller system Bacchetta uses worked well for this purpose.
So here’s a picture of the finished prototype.
It rides great! Nimble like the Rans Rocket, but fast like a Bacchetta if I recline the seat enough. I rode it for a few weeks around my home in Morgan Hill, CA, and it did just fine. I got cocky and decided to enter the Oregon Human-powered championships, held May 24 and 25 at Portland International Raceway. That should be no problem with a suitcase bike!
Before you get to the Friday packing part, here are the extra steps: remove the seat, undo the master link on the chain, put it in a plastic bag so it doesn’t get grease all over everything, then unclamp the boom. Not too bad, about 10 minutes worth.
Now go through the usual Friday packing procedure. Then work the boom in around the bike. Dang, it won’t fit with the cranks attached. OK, undo the cranks from the boom and fit them in separately. Almost done, just fit the seat in on top of the bike and close the lid!
There’s no way the lid going to close without separating the seat in two. So out comes the hacksaw again, and off to the hardware store again for some more mending plates. The result works from an engineering standpoint, if not too aesthetically pleasing (nothing a little black duct tape won’t hide).
Now the two parts of the seat go in and the lid closes! With me kneeling on it while I strain my fingers working the latches, hoping I’m not bending anything critical inside. There’s a good chance if TSA pops this open to inspect, they’ll never get it closed again. All right, so it’s a two suitcase bike. Thank goodness Southwest Airlines lets you check two. The seat goes in the bag with my clothes.
I flew to Portland a day early so I could show it off to my friends at Friday in Eugene. It took less than 10 minutes to reassemble the bike! That’s aside from the recumbent part, which took a further 90 minutes, much of which was spent on reassembling the blankety-blank seat.
I finally made it to Fridayâ€™s facility. Now, I was a bit embarrassed showing off my kludged-together contraption to professionals, but it was warmly received. Alan Scholz and a couple of other guys took it for a ride and came back smiling. My favorite was when I tried to explain that the seat didn’t adjust, so only people with about the same leg length as me could try it out. Someone took one look at the bike, laughed and said “Rich, you don’t need to explain why the seat doesn’t adjust”.
So feeling nicely reassured that the folks at Friday didn’t mind too much what I did to their creation, I headed up to Portland for the event. I had scratched the decals during the conversion process, so they steamed them off for me at Bike Friday and gave me new ones to replace them with. But I managed to promptly lose them!
So I showed up at the Portland raceway with an unidentified bike, but at least I was wearing my Bike Friday Jersey. It was well received, and more than one person who fondly remembered the SatRday said they liked it. As I was zooming by (at least it seemed like zooming to me) in the time trial, I heard some â€œgo Friday!â€ shouts.
I must say in this crowd I fit right in, in fact this was one of the tamer of the homebuilds. I think my favorite was a front wheel drive recumbent where you pedal with both your hands and feet. Quite a good workout, the rider was quite fast on it, but man was he huffing and puffing afterward.
As far as the racing results, the bike did pretty well, although it could do with a better engine. I’m working on that, but with a vintage 1953 engine thereâ€™s only so much you can do.
In the racing class of recumbents without fairings, the bike got soundly whupped by the â€œlow racersâ€ which are super-aero with the rider very low and almost horizontal — itâ€™s a bad sign when you can see them balancing themselves by laying a hand on the ground while they are standing still.
The â€˜bent Friday held its own, though, against more upright (and practical) â€œhigh racers.â€ So if you like a fast practical bike like the performance bikes by Bachhetta, Volae, etc, I think this design could be a travel worthy equivalent (if we can get the packing time down from 90 minutes).
Since the Portland trip, Iâ€™ve also ridden the bike in a human-powered vehicle event at the Hellyer velodrome nearby in San Jose. It was exhilarating riding it on the banked turns, which I had never tried before. I even played with swooping down from the banks into the straights like the track cyclists do in match sprints. I was glad to have brakes, though, unlike track bikes.
But I must say that, like most â€˜bents, this bike shines the most as a comfortable cruiser. Lazyboy on wheels!
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