17 February 2016

Cruzbike -- A better recumbent bicycle design?

With "normal" road and touring bicycles, design is a matter of minor refinements.  Different sizes, thicknesses and shapes of tubing, a slightly more or less compact triangle or maybe some "aero" features.  There is very little in the way of radical departures in design. The basic frame geometries were established long ago. UCI rules enforce orthodoxy, as do the laws of physics and human anatomy, which intersect well with the longstanding main+rear triangle design, and a relatively narrow range of front fork "trail" and other measurements.  Deviate too far and you will be punished with an unrideable monstrosity.

In contrast, recumbent bicycles still leave a huge amount of room for experimentation. First, the UCI rulebook is thrown out the door. And the different seating positions allow different approaches to the human/bike interaction and to accommodation of human anatomy. We see everything imaginable -- from fully faired "velomobiles" to trikes with the rider lying on his/her back inches above the ground, to almost "normal" looking seated riders, to large aluminum boom-based bikes like the popular Bacchetta (Italian for "stick" or "rod"), and mix-and-match versions of these and other concepts. Recumbents are interesting to look at and figure out just how (and how well) they work -- with their long chains and tensioners.  I enjoyed riding nearby many recumbents at PBP -- passing and being passed by the same riders many times on the rolling hills outbound from Paris the first evening as light faded.  I would pass on the climb, a recumbent would pass back on the descent.  Repeat.  Repeat.  and ... repeat.

I once had a Trek R200 recumbent, purchased at a deep discount on a close-out sale when I lived in the U.S.  It had a "double rear derailleur" drivetrain, a rear suspension, and small wheels.  It was the only recumbent model Trek ever made, and it is the only Trek bike I ever bought. I gave the R200 to a friend when I moved to Japan -- the heavy, unwieldly frame was not something to add to our moving baggage, and I had no idea where I would store it in Tokyo. Besides, it was SLOW climbing hills.  I could almost feel the blood rushing to my head as I desperately, slowly, spun up the road near our house with my toes pointed into the air.
Trek R200
In Japan, I have never considered a recumbent.  A bicycle that does not climb well is poorly suited for a country where all the good rides involve mountains! Nor is a design that is bulky, hard to store and that cannot easily fit in a "rinko" bag or onto a train well-suited to Japan.  Even the lightest recumbent is around 12 kgs -- probably 50% heavier than a typical road bike.

But last summer at PBP, one of the U.S. riders staying at my hotel had a recumbent, a Cruzbike Silvio.  It struck my eye immediately.  Most recumbents have long, long chains stretching from the pedals in front all the way to the rear wheel, a tensioner/guide somewhere in the middle of the chain. Like this:
A Bacchetta -- long wheelbase and very, very long chain.

The Cruzbike is a bit different.

-It has front wheel drive!
-The chain length is about the same as a "normal" upright road bike.
-The bottom bracket and front pedals and cranks are on a rotating steerer stem connected to the handlebars and fork.  They are also connected to the wheel by front "chain stays" -- a kind of "front triangle."

The Silvio, which has some "suspension" to soften the ride in the rear, looks like this:
I was told that this demo bike, used at a recent show in Seattle, is available for $4000 at Rose City Recumbents.
Normal retail for the Silvio/standard build is something like $4400
A frameset is available for $2600 direct from the manufacturer.  .
There are other models besides the Silvio, and the fastest is now the Vendetta, which features a more horizontal rider position and no suspension.

In order for the front wheel to steer the bike, and also drive the bike, the bottom bracket and pedals are not attached to an immovable boom, but rather to a set of stays with the handlebar that turns along with the front wheel.

When I first examined it at PBP, the bike looked odd.  Especially the need to adjust pedaling leg lengths as one turns.  But the rider I met said it is easy to adjust to the moving BB and that his Cruzbike climbs well.  The manufacturer website notes that Cruzbike holds RAAM and other records for speed and is the only recumbent that "climbs like a road bike".  The climbing capability comes from the ability (and need) to use one's upper body while climbing, to push the bars opposite of the leg that is applying power -- very similar to when "dancing", out of the saddle, on a normal road bike.

Rose City Recumbents were kind enough to let me test ride the Silvio.  They warned, however, that it is not easy at first to ride a Cruzbike.  Almost impossible until you "get the hang of it".

They were right!  I struggled for about 15 minutes, but the best I could manage was 3 or 4 pedal strokes before I would veer off to one side and need to put a foot down to stop from falling.  Often I would only get in a single stroke.  They told me that I should sit upright and push with my legs to get up some speed before sliding into the seat and trying to pedal. Eventually I settled on downhill starts, on a ~2% incline nearby the shop.  This allowed me to practice balancing on the bike at various speeds WITHOUT trying to pedal.

After a break for a scheduled telephone call, I tried again.  With the downhill starts, I at last managed to pedal smoothly while remaining upright.  I could make it down a street of 2 blocks, turn a corner, then climb a steepish hill into a cul de sac.  After putting a foot down, I could head down the hill, around the corner and back up the first street.  After a few more trips, I could sense when the bicycle was going fast enough so that I could steer by leaning, and when it was slow enough so that I needed to "use my feet" as I was told.

So after a total of 30 minutes on the bike, I could at least get the sense that, yes, I could ride this without difficulty if I worked at it.  And I could see Jonathan, of R.C. Recumbents, ride another Silvio in tight circles and even with his hands off the bars.  Jonathan said it took about a week until it felt as easy to balance on the Cruzbike as on a normal bike.  He said kids can do it right away ... especially those whose muscles remember riding a "big wheel" tricycle.  Regular cyclists need to "unlearn" their usual tricks before they can ride it successfully.

As for the overall feel, climbing was, indeed, a different sense than I remember from the Trek R200. Eventually, I think it might climb as fast on it as a road bike.  I immediately felt that I was putting MORE pressure on my knees pushing the pedals and driving my back into the seat cushion than I normally would spinning a road bike.  I would need to be careful not to use too big a gear on this bike. And I was definitely using different muscle groups than I normally do when riding.

A Cruzbike might prove to be a good way to ride long distances in more comfort than with a normal bike.  No worries about pressure on hands or butt/groin.  And it might be a great way to get through a truly "yuge" (as "the Donald" might say) cycling year without physical problems -- indeed, I have read that Kurt Searvogel used a recumbent on some days of his HAMR effort last year, to vary the punishment his body took in riding 75,000 miles in a year.

Maybe it is the way to the next level of craziness in cycling ...

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