In response to my Have bike, will pedal post, Fran asked:


It's actually something I've been meaning to blog about for a while now, but I've been trying to think of a way to explain the difference in balance between the two without being able to resort to hand gestures. (Also, since I'm not a physicist and haven't played one since high school, I don't know the technical terms.)

Have you ever kayaked? You know the way the boat responds as you dip and pull with the oar on the left side, then shift your balance towards the other side, then dip and pull on the other? You're proceeding forwards, but your forward momentum is affected by and dependent on a constant series of shifts to the left and right.

This same sort of process takes place when you're pedalling on a recumbent bicycle: you're pushing with one foot, then with the other, and because your legs are stretched out along the length of the bicycle, rather than positioned up-and-down at the bicycle's centre, the bicycle sways from side to side in response to the forces of your pedalling.

At very low speeds, yes, it's harder to balance because the forward momentum of the bicycle is not enough to overcome the pull of gravity and you don't have your own body's years of training in "behold, I am upright!" to overcome this.

Riding close alongside another bicycle, the constant shifting of a recumbent bicycle makes the probability of nudging your companion just that little bit more likely. Riding in a group, where the riders are riding in a paceline, taking turns at the front and then dropping back ... well, that's tricky to coordinate at the best of times.



Edit:
On the way to work this morning I was riding behind a guy on a mountain bike. His seat was too low, so his knees were sticking out like Prince Charles's ears, and he was riding very slowly. He was weaving side to side as a bicycle will do under such circumstances.

Which got me to thinking that the physics of an upright bike aren't that different to that of a recumbent. If you're riding hard on an upright bicycle, you'll see that the bike shifts from side to side in response to the forces being applied: it's just that your butt, not having to stay in the seat to support your body weight, doesn't need to follow it.

Clunk. Click click. Hisssssssss.

It's not a sound you ever want to hear coming from your rear wheel. I felt it as much as heard it this morning, about 2kms into my morning commute, and brought the recumbent to a stop.

At first I thought it was my waterbottle again, repeating the grand escape it had made yesterday afternoon - only choosing this time to hit the wheel of my bike instead of rolling under a passing car. The hiss of escaping air quickly put paid to that idea.

A quick inspection revealed a piece of metal, a length of wire about the thickness of a carpentry nail, curved rather like a fishhook. It had driven itself into the tyre, gouged a crescent-shaped slice in the kevlar, punched a good sized hole through the inner tube.

I walked home.

I haven't been riding to work since the beginning of January.

A combination of too many years at a computer desk, extended time in the saddle over the Christmas break, and the final straw of several hours crouched in the garden left me with a pinched nerve (C6 on C7, for the curious) in my neck. I'd thought that the waves of pins and needles running up my left forearm would go away when I stood up; two weeks later I was still waiting.

Several months - and a good number of physiotherapist visits - later, I've maxed out the physio bonus points on my private health insurance. I'm having to watch my posture (James has been commenting frequently on how upright I stand of late), and perform neck retraction stretches at 15 minute intervals, but things finally seem to be under control.

I'm still not entirely symptom-free, and I'm cautious about triggering a relapse by jumping back on my bike. On the other hand, I've also been going stir crazy from the lack of exercise (and the lack of fun!) that the loss of my daily bike commute entails.

This past week, however, I've found an alternative. I've borrowed Moz's recumbent bicycle - not the one pictured above, but similar: short wheel base, above-seat steering. It's taking me awhile to get the hang of the different handling of this strange machine, but I'm back on two wheels again and - better yet - I'm not getting any of those prickling sensations in my arm while I'm riding.

I'm starting to worry, though, about the prickling in my chin. Is that my recumbent rider's long grey beard starting to grow in?

Warmshowers.org, the Warm Showers List for Touring Bicyclists, put us in contact with Robert and Emmy, who have just finished a 6 week tour of New Zealand on their M5 recumbent bikes.

They weren't expecting to spend a full weekend in Sydney, but they found themselves with a day to spare while Qantas hunted down one of their bags which had gone missing in transit. That could almost be considered good luck: it would have been a shame to pass through Sydney without seeing any of it.

Their journal is in Dutch, but between Babelfish and the photos I can follow along.

Good luck with the rest of your trip, guys!