Saturday, February 25, 2012

Wireless brakes. Not a fan.

Therefore, the Saarland computer scientist's mathematical methods should now verify the correct function and interaction of the components automatically. "The wireless bicycle brake gives us the necessary playground to optimize these methods for operation in much more complex systems," Hermanns adds. Therefore, his research group examines the brake prototype with algorithms that normally are used in control systems for aircraft or chemical factories. As a result, they found out that the brake works with 99.9999999999997 percent reliability. "This implies that out of a trillion braking attempts, we have three failures," Hermanns explains and concludes: "That is not perfect, but acceptable."


D - there are also wireless bicycle brake-and-signal lights.
I'm not a fan. Here's why.
Wireless means wireless hacking. I've picked up a 2600 mag in my time. Only that magnetic near-field tech that is being developed for secure financial transactions is tolerable.

Wireless brakes on a bike sounds like a good way to get killed.

Sunday, February 19, 2012

lee valley belt instead of chain?

D: I'm not sure about if this would require an intermediately placed cog mid chainline (belt) to avoid slippage. Not sure how strong it is, though presumably it is fine.

Seems to me that this would play well with the FB Greenmachine's intermediate frame-enclosed gear hub and suspension point.
I'll keep it in mind for future projects.


Aside - Freelight-based generator.
I found those N48 magnets to use in 1/4x/14" rod form form 3 per dollar.
I figure I use some machine guard plastic I have. Cut 2 discs out of it, glue together for a thickness of about 1cm or so. Drill out so it fits snugly on a pedal crank. I don't it flopping around. Only 1 of those discs needs to be full size.
I drill out 1/4" dia. pockets along the outside rim edge. Ensure equal depth. Seat those magnets with a touch of glue (or just press fit) along edge. I think I'll need about 20 of them. The disc diameter is largely determined by plans to mount the magnet dynamo on the bike frame. I suspect inside the triangle of a diamond frame is best.
The power conditioning equipment is beyond my limited skills, though. I'll need to ask more technically inclined peeps.
I suspect pulse trickle charging a battery, and powering everything off the battery will be easiest.
The circuit can be made to draw power in between recharging pulses.
While we're at it, just running all the possible power wire inside the bike frame would work.

Friday, February 17, 2012

clever 3 speed unicycle rig

So when I was informed a few months ago that Sturney Archer had just released an internal hub for fix gear bikes I ordered one immediately!

The S3X has 3 speeds of 1.00, 0.75, and 0.625, so nowhere near the nuvinci's current 360% range but on the plus it's just $140 and it works bidirectionally out of the box.

My goal was to try and design a drive around this that could be attached to a standard uni frame with no modifications. Here is what the spacial concept was like:

29" KH frame, both chains on the inside, with one going from the pedal drive sprocket up to the input of the S3X hub, and the other from a sprocket on the flange of the S3X hub down to the wheel.

A cross sectional view of the hub itself should be pretty self explanatory. The spindle and cranks naturally spin independently of the hub body:

I had a few bike sprockets pulled from cassette freehubs kicking around, so with the pickings from that I designed it for 28 teeth on the pedal, down to 15T on the S3X. Then the bolted to the flange of the S3X was a 21 tooth, which connected to an 18 tooth on the wheel.

So the overall chain ratio was 28/15 * 21/18 = 2.18

Combine that with the 1.0, 0.75, 0.625 ratios of the S3X hub and the 24" wheel and the final result should be a uni with the physical size of a 24" but 3 speeds of 52", 39", and 33"


D - very nice! Maybe my mid-steer thru-front-wheel-pedal will need to use this layout initially. Until the gear hub companies take notice and build them for this layout.
Though a hydraulic pump so it is RWD might be simpler, ultimately.
The mid-steer with FWD will need at least a lite 12V rear e-assist for moving uphill on loose gravel.

D - to be fair, with Justin's clever layout, there is really no limit to what gear hub could be used. A Rohloff becomes practical.
The hub on my bike layout would make sense as far forward as possible, to add ballast to the front tire on a FWD bike.
Ditto a battery pack for the rear tire E-assist.
As a bonus, my layout would not flip forward like a standard SWB. I had to loosen the front tire to prevent that. My Cruzbike became a unicycle briefly, when I most needed 2 tires!

Um, is Rohloff ever gonna release that new lighter 580% gear range gear hub? I don't mind that it cannot handle too much torque. After all, the lack of weight on the FWD front wheel of my proposed mid-steer means the tire will slip well before the gear hub fails.

Monday, February 6, 2012

on solar power on top fairing on bike

D - sheesh, hard to find detailed size/ dimension/ weight info.

Roughly, 1x2', c. 6W, c. $200 bux.
And for less than a POUND.

D - I don't need that much flexibility.
Just being able to flex along the top fairing ogive would suffice.
But dunno if any rigid plastic units can do so.
Anybody know?

D - the initial fairing project was just gonna use a 4x8' of Lexan, with half for the top and bottom fairing respectively.
Just gonna cut out outline, flex and clamp into place.
No fancy 3D bubble blowing to start. Maybe later.
I don't have shop setup, though could manage it in my basement.

D- so 2 of the above panels would run a shocking $400 bux. I say that as a guy who is not working full-time yet.
BUT 12Watts of power to play with...

In my last blog, I mused about using a non-freewheeling direct drive hub motor to
1) get power for a burst when needed from a battery and capacitor that
2) it trickle charges when needed or
3) power lights at night or
4) consumer appliances by day.

D - the solar power concept involves some modifications.
1) a motor for use at typical day touring speeds, less torque, higher top RPM (it's OK if during commute speeds, or downhill, if it is not of use - more important to be also of use on gradient during a long haul slog)
2) charges battery to power the lights at night,
3) powers consumer electronics during the day.
D - you would want the solar permanently affixed to the top fairing, which is itself securely anchored to the bike frame.
Down the road, a secure closing 'clamshell' layout can alleviate theft concerns. Once the bike frame concept gets turned inside out, we know longer have an endoskeleton with a fairing on it.
The fairing becomes structural, a true endoskeleton. Like a lobster.
The process of smashing into the bike precludes stealing an intact bike. If the bits are attached securely, looting it is not rewarding either. Finally, a thoughtful redesign of that sonic alarm lock I have 2 of will be the icing on this cake.
If you cut the cable, you have a wailing bike.
I'd like to add flashing lights too.

Clearly some of my power system ideas require a real technically savvy power system designer.
My bro in law knows lotsa other engie specialists. Plus a galpal is dating a guy who builds electrical systems.
I do rely heavily on others for that with my liberal arts back ground!

Sunday, February 5, 2012

12volt generator idea

D - see John Tetz's idea at IHPVA.

I wanted a very light power assist only. Tetz pioneered that.

Other sites say you want something so big and heavy that you then NEED it to accelerate quickly or to go uphill. Basically a motor that can deliver 100W to match the typical rider's 100W.

Today I was looking into the idea of rewiring (or findig ) a hub motor to 12V that
1) has a direct drive and no freewheel, and
2) a planetary gear for better torque.
These ARE quite light compared to the typical alternative.
I like the idea of a constant-draw generator that
1) can be used via battery as a motor
2) charges that battery
3) powers lights at night or
4) powers a car-style cigarette power adapter for various appliances such as
i) music player
ii) cell phone
iii) GPS unit.
On a road trip (or cross country tour), I'm always gonna be using it for those 4 uses anyway, so don't mind the constant draw. So long as it is not too much.

However, not cheap and much hassle to install a hub motor for all that.

I found this decade-old obsolete ZAP Zeta III rim motor.
There IS 1 on ebay this month. POS with dead battery, but I can do that externally. Plus the battery tek has come a long ways since then. I'd like brushless too but meh.

Clearly this won't deliver much torque. But it lets me explore some ideas.

For brief and strong assist (at 2x the motor capacity, for a short period before the overheating causes permanent damage), the former 12V hub motor is better.
Based on my results with the ZAP, maybe I'll be encouraged to continue this project.
With so little juice, the structural components could be trimmed down to save weight.

Again, I'd note that the steady RPM at the pedal makes the crank and bottom bracket ultimately a much more sensible place to place a dynamo or generator.

I wonder about my 'nitro boost' idea for a brief power surge when you need it using a capacitor array.
When a big dog is chasing you, there is no such thing as too much power!


Saturday, February 4, 2012

just for kicks - the penny farthing original bike

Your delightful bicycle, with its different sized wheels, is called an “ordinary” or more commonly a “penny farthing.” This name is a reference to the large penny and the small quarter-penny (farthing) coins used in England in the past.

A Frenchman, Eugene Meyer, is credited with inventing the “high bicycle” around 1870. He based his bicycle design on the theory, the larger the front wheel, the farther one could go with each pump of the pedals. In the 1880s, an Englishman improved on Meyer’s contraption and Victorian England went crazy over penny farthings. There were competitions involving hundreds of bicycles and a plethora of newspaper reportage and cartoons featuring people pulling “headers” (going over the handlebars) or falling backwards when riding uphill. After the invention of the “safety” bicycle that had two identical wheels, the old-fashioned PF was referred to as the “ordinary.”


D - hmm, the pedal-thru-front-wheel mid-steer concept is a descendant of this.