Monday, February 14, 2011

Recumbent Bikes vs. Trikes

Recumbent Bikes vs. Trikes
by Bevin Chu
Taipei, China
February 5, 2011


Bikes vs. Trikes

I recently decided to switch from uprights to recumbents. My first choice for a recumbent was a SWB low racer.

Upright Bike, Diamond Frame (DF) Configuration, possibly a Felt

In a previous article I outlined my reasons for choosing a SWB low racer. The primary reason of course, was seating height. On a SWB low racer, one sits only 36 cm or so off the ground, depending on the make and model one is looking at.

Recumbent Bike, SWB Configuration, Performer Low Racer Caliper
http://www.performer.com.tw/2010/user/product_2.php?wp=05&sno=00067

But after I posted that article, a couple of experienced bent riders suggested that rather than switch from upright bikes to recumbent bikes, I should consider making an even more radical switch, from upright bikes to recumbent trikes.

Recumbent Trike, Tadpole Configuration, Performer JC-70 CM Sports Trike
http://www.performer.com.tw/2010/user/product_2.php?wp=05&sno=00059
http://www.flyingfurniture.com.au/shop/product/performer-sports-trike-cromoly-jc-70-cm-27-speed

They suggested that although my injuries might be milder falling from a recumbent bike than from an upright bike, that I should avoid injuries altogether, by switching directly to recumbent trikes.

They may have a point.

Geometry 101a

As anyone who ever took a basic geometry course in high school knows, two points determine a line, and three points determine a plane.

Two points determine a line

Three points determine a plane

What does this have to do with cycling safety?

Why everything.

Bikes: Two Point Support

The reason bikes fall over, is that they are supported at only two points, the front and rear wheel contact patches. Therefore if either of the two contact patches experiences a sudden loss of traction, the bike falls sideways and unceremoniously dumps its rider on the ground.

Please note that I am addressing only falls resulting from a loss of tire traction on the pavement. In a lifetime of bike riding I have never fallen because I "lost my balance." Therefore that is not an issue for me.

As I pointed out in great length in my previous article, "From Wedgies to Bents," a bike rider's injuries will be far greater falling from a "conventional" upright bike, than from an "unconventional" recumbent bike.

This is especially true if the upright bike rider is taller than average in height, and must set his seat at a considerable height above the ground for proper leg extension. My own DF seat height must be set a full meter above the ground. Had I been riding a SWB low racer during my recent spills, my injuries would have been trivial by comparison.

This was true when I wrote it yesterday, and it is just as true today.

Trikes: Three Point Support

But what if one could avoid falling altogether? What if instead of merely minimizing one's injuries from a fall, one could eliminate injuries altogether, by not falling in the first place?

How would one go about avoiding falls completely?

The only way to do so, would be to switch from bikes to trikes, rather than from bikes to bikes.

As noted earlier, the reason bikes fall over, is that bikes are supported at only two points, the front and rear tire patches. Therefore if traction is suddenly lost at either of these two contact points, the bike falls sideways and dumps the rider unceremoniously on the ground.

This can never happen on a trike. The reason a trike can never fall over, is that trikes are supported at three points, at all three front and rear tire patches. Therefore if traction is suddenly lost any of these three contact points, a trike will not fall sideways. The trike may skid sideways, but it will remain upright.

Trikes: Rollovers are Possible

The only time a trike will not remain upright, is when it changes direction so abruptly that it "trips" sideways on one of its wheels and rolls over. A trike cannot fall over, but it can trip over. The bad news is that this is possible.

The good news is that even when it does happen, the recumbent triker is still better off than the upright biker.

The recumbent triker falls from a seat only 23 cm or so above the ground.

The upright biker, on the other hand, falls from a seat a 100 cm above the ground. What's worse, the upright biker's shoulders and head are situated another 50 cm above the seat, i.e., a whopping 150 cm above the ground.

The difference between falling 23 cm and falling 150 cm may mean all the difference in the world.

Convenience Issues

Another consideration is convenience. Unfortunately a tadpole trike would probably be less convenient than a SWB low racer bike.

I live several stories up in a multistory condo. I'm not sure how convenient it would be to schlep a tadpole trike up and down a cramped elevator. I suppose I could tilt it up vertically on its single rear wheel, while pressing the two front wheels against the rear wall of the elevator.

This maneuver would probably be easier with a SWB low racer bike than with a tadpole trike. A SWB low racer bike is narrower and lighter. It could probably be tilted up vertically on its rear wheel more easily than a wider and heavier tadpole trike.

It might even be easier with a delta trike. A delta trike has two rear wheels. Tilting a delta trike up vertically on its two rear wheels, while pressing the single front wheel against the rear wall of the elevator would probably be easier.

A narrow SWB low racer bike would probably be easier to ride through narrow alleys crowded with pedestrians than either a tadpole or delta trike. I would be less likely to find myself backed up in traffic on a SWB low racer bike, than on either a tadpole or delta trike.

Further investigation is needed.

Where Does that Leave Me?

So where does that leave me?

Basically it leaves me at "Let's wait and see."

I am still recovering from the soft tissue trauma to my left knee. I am still giving the suspected fracture in my left scapula time to heal. Several months of physical therapy are still required. I have plenty of time to mull over my next step regarding "human powered vehicles."

My decision to cease riding "conventional" DF bikes has already been made. That decision is firm. My days of DF riding are over.

My decision to begin riding "unconventional" recumbents has also been made. That decision is also firm. My days of recumbent riding are about to begin.

The only question that remains now, is "Recumbent bikes, or recumbent trikes?"

Performer Low Racer Caliper, a SWB low racer
http://www.performer.com.tw/2010/user/product_2.php?wp=05&sno=00067

Performer JC-70 CM, a tadpole sports trike
http://www.performer.com.tw/2010/user/product_2.php?wp=05&sno=00059
Similar model, reviewed by Utah Trikes
http://www.utahtrikes.com/TRIKE-PERFJOURNEY.html
http://www.youtube.com/watch?v=QXwcywqv8yY

Perhaps one of each?

4 comments:

Troy said...

What did you decide? Trike or Recumbent? I'm facing the same decision.

Troy said...

What did you decide: trike or recumbent? I'm facing a similar decision...

Bevin Chu said...

Dear Troy,

I decided on a recumbent bike. But that's because the streets here on Taiwan are so narrow.

If the streets where you live are wide enough, I would get a trike. The stability is nice.

Hope that helps.

Troy said...

Thanks Bevin. I went to go test ride some recumbent bikes today. They were nice, but I'd like to test ride some trikes as well to compare. Cheers!