Friday, May 2, 2008

pedal-thru-front wheel mid-wheelbase. air power.

D: the top pic is the subject of discussion- a new "Penny and Farthing" bike.
"The ordinary, high wheel or penny-farthing was the first true bicycle with which actual speed and distance could be achieved in a practical manner. Given the absence of a stabilising steering system, larger and larger wheels were built with the intention of increasing stability at speed. The classically oversized penny-farthing wheel, which measured 1.5m (60") in diameter resulted in such large gyroscopic force that it was stable without a caster steering system. The name refers to the British penny and farthing coins of the time; the former being much larger than the latter so that the side view of the bicycle resembled two such coins placed next to one another."

D: good thing it's stable. Just imagine hitting your head on the road from that height!
Without a gear hub, I imagine this was hard to start, then hard to accelerate beyond a certain point. To this day, a few bikes don't have gears. Which is fine, I guess. If you only every wanna go about 10kph or whatnot.
The size of the tire v.s. a person's leg is the ultimate speed limit for bike like this.

Well, what is old is new again. I am exploring reintroducing the pedal-thru-front-wheel concept. However, in my case, with a mid-steering full or semi recumbent.

Regarding my pic:
1) top: this sort of bike going uphill, with power assist on rear tire.
2) right: front profile of a variant partial fairing based on the 'Wisil Missile'.
3) bottom: a concept bike that can be both pedal behind or in front of front tire.
4) left: toying with the Tron Lightcycle theme, a look at today's bike inside a Tron style fairing.
With a few tweaks, the overall body shell shape is not bad for drag!

(Aside: I am exploring a motorcycle with similar motif. The motor is inside the centre of the ridiculously oversized front tire.)

This bike concept bears a resemblance to the mid-wheelbase recumbent design.
In this, the pedal and crank are over the small front wheel.
It also bears some resemblance to the Cruzbike. With that bike, the rider pivots his legs to keep them aligned with the front wheel during turns. This makes the chain line simple.
I did find one SWB (short wheelbase) 'bent with that concept.

The idea of front wheel drive (FWD) is appealing. No long chain to the rear tire.
No heel clip issues with mine.

I could use various mid-steering approaches. Flevobike has historically been synonymous with mid-steering. In the DIY category, the Python.
"Learning to ride a Flevobike takes some time, in contrast to almost all other recumbent bicycles. It took me in total about 5 evenings of practice on a regular Flevobike. After that, riding the Racer was not difficult anymore.

I am very enthusiastic about the centre-pivot steering of these bikes. It makes for a very relaxed ride, as you do not need your hands to steer. However, there are disadvantages, too. Going up a steep hill you will notice the lack of surface grip under the front feel, due to the fact that the weight is transferred to the rear wheel because of the inclination. And with heavy loads (holiday luggage), the bike can become somewhat unstable and you will need both hands on the steer. "

D: the Python was listed yesterday.

I figured I would need to use a Rohloff speedhub with internal gears in the front tire axle.
I'll be honest - I have no idea how I plan to attach this thing!!!
For a commuting bike, a more modest hub would work. The Rohloff is over a 1000 bux - yikes!
Still, think about it. No chain, no dirt in it, no grease on your pantleg. No noise from the chain.
No chain to break or fall off.
This is even more elegant than the 'chainless challenge' variants!

The mid-price drives that come to mind are I-motion 9 and the NuVinci.
Both are 300-400ish bux. Both have a c. 350% gear range.
Contrast that with the Rohloff with more like 525, 575 on their next-generation prototype.
I tried repeatedly to contact the I-motion company for details about their drive. First, I got interrogated as if I was some industrial spy. Then he simply sent the canned PDF of info. I was specifically asking how many gears were internally being used in gears 1-9. He was a useless P.O.S..

I needed to know that! For example, the Rohloff uses only one internal gear in gear 9. However, 3 in gears 8 and 10. But 2 in 7 and 11. Ergo, one should try to stay in 9, but switch from 8 to 7 when slowing down and switch from 10 to 11 when speeding up.
I had some ideas about using the Browning product below with programming tweaks to sweet-spot the cadence with this in mind. Pretty sophisticated stuff.

He also made me mad enough that I started researching the NuVinci.
It is superior in every respect except for weight- about twice as much.
D: I've seen it online for as little as 350 bux.
It doesn't have gears per se.
It is the first practical bicycle CVT (continuously variable transmission).

I'd like to find some parts from the defunct Browning Automatic Transmission to try to link to it.

D: I need to deal with the lack of traction uphill on poor surfaces. The best I could think of was power assist on the rear wheel with the ballast for it in front of the front tire. It could be electric or air or whatever.
I will be looking into getting some firefighter air tanks. They're 4500psi. A bud of mine works at a scuba shop, so I have access to safely underpressured 3000psi refills.
The composite tanks are pretty light!
They are, however, rather bulky.
For that reason, a series of propane air tanks might be desirable.
I'd like to suggest one variation in the design suggested. Don't use paint inside.
Take a model kit for models. The scrap plastic, dissolve it in acetone.
As the acetone evaporates, the plastic is laid back down in a thin layer on substrate.
The result is an excellent plastic layer v.s. water corrosion.
Alternatively, a 300psi BBQ propane tank would be HUGE but could be easily refilled with a tire air pump at any garage.

I did the calcs for solar power assist/electric last night, but we'll save that for another day.
D; here is my initial foray into air power assist.
Recumbents stand to benefit from brief high-torque assistance. They are soooooo hard to start on an incline.

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