Please email me if you have any other questions!
How does the 4PowerBikes arm-power kit compare with other "rowing bikes"?
Controlled motion. The 4PowerBikes arm levers are linked to the crank-set, much like an engine piston to a crankshaft (or a locomotive steam piston to the driving wheels). This provides a smooth, controlled motion, unlike other rowing bikes, which typically have a "ratchet" or "freewheel-and-rewind" mechanism (you pull a chain around a cog or a cable around a drum until the end of the stroke, then you stop/reverse direction and a spring rewinds the chain or cable). This stopping/reversing requires energy from you. In contrast, the 4PowerBikes mechanism conserves your energy. Decelerating your arms at the end of the stroke puts energy into the bike's momentum; at the start of the next stroke the link to the crank-set allows the inertia of your feet and legs to help accelerate your arms into the power stroke.
Power on both forward and reverse strokes. The 4PowerBikes mechanism lets your arms add power to the bike on both strokes: pulling and pushing.
Retains conventional pedal motion. The conventional bicycle rotary pedal motion is retained by the 4PowerBikes mechanism. I've tried linear (back-and-forth) pedal mechanisms, even those with controlled motion, and they've never felt nearly as smooth or as efficient as pedaling.
How do you steer?
In addition to moving back and forth (pivoting about a horizontal axis), the arm levers also "twist" (pivot about a vertical axis). So you can move one arm slightly ahead of or behind the other while you're rowing. That "twisting" motion is what steers the front wheel.
It turns out that your body is pretty finely-tuned to feeling and making slight differences between your two arms — that is, steering — even while pushing or pulling very hard.
Is it hard to ride?
No. If you can ride a recumbent you can ride it with arm power.
Why have both arms move together? Why not have them move oppositely to each other, and to your feet, like when you're running?
"Rowing" instead of "boxing" makes the mechanism much simpler and lighter. There's no simple way to steer while your arms move opposite one another.
Isn't it weird to be going back and forth with your arms while your feet go round and round?
No. Maybe it looks weird, but it feels fine.
Can you "coast" with your arms while your feet keep pedaling?
No. The arm levers are linked — like a piston to a crankshaft — to the crank-set. This linkage is necessary so that the inertia of your feet and legs helps pull your arms through the ends of the arm-power strokes — otherwise, your arms would tend to get "stuck" at one end or the other.
The only way to "unlink" your arms from your legs would be to have some kind of clutch mechanism that would disengage the arm levers from the crank-set.
While I initially thought of adding such a mechanism, I quickly got used to the arm power motion. I never feel any need to "rest my arms." After a couple of years I even found that I could ride — and pedal at the same time — one-handed. (I wasn't working on being able to do this; it just turned out that eventually I could!)
Therefore, I haven't created a "clutch" for the arm power levers.
How much weight does it add?
The net weight addition is about 2 pounds.
Is it worth it?
Yes, I believe it really is. In the tests described in the article, the arm-power recumbent beat my uphill times on an upright — and the recumbent was about 5 pounds heavier.
Nowadays, if I'm following an upright rider up a long hill, in those cases where I'm struggling a bit to keep up it's always a good sign when the upright rider stands up out of his saddle. Most of the time that means I'm going to catch them. Most upright riders don't seem to know that they slow down a bit when they stand up. In addition, I conclude that pedaling standing up is much less efficient than normal. So they lose efficiency and energy, while I stay on-track.
Will it work on my bike?
The kit is intended to work on any recumbent — we have different clamp sizes for different frame tubes, and the links are adjustable. Nevertheless, it can take a bit of work on our part to find a mounting that works — that is, doesn't interfere with the chain, gives a good steering connection, etc.
So send us an email indicating the bike on which you'd like to try arm power, and we'll figure it out.