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# elliptical sprocket

Eqalize the torque at all phases of pedalling.
 (+2, -1) [vote for, against]

When pedaling a bicycle, the maximum torque occurs when the pedal stems are horizontal and the rider is pushing strait down. The least torque occurs when the pedal stems are vertical and the rider is pushing them forward or backward. To equalize the torque throughout the cycle, I suggest an elliptical front sprocket with the pedal stems across the narrowest part of the sprocket. That way, the power ratio would be greatest when the pedals are horizontal and the at the highest torque. The power ratio would be lowest when the pedals are vertical and the torque is lowest. It would be like changing gears several times through the cycle.
 — tonybe, Feb 13 2018

Baked; WKTE; not shown to be useful AFAIK (in either orientation). [notexactly, Feb 14 2018]

Epitrochoids at a glance. https://giphy.com/explore/epitrochoids
[2 fries shy of a happy meal, Feb 20 2018]

 Elliptical chainrings are already available, with the benefits claimed as you describe. Look up "osymetric chainring" for a particularly non-round design.

I have ridden a bike with one (for about five minutes), it feels very weird.
 — mitxela, Feb 13 2018

They are baked I'm afraid. Check out Shimano's "Biopace" which appear on the occasional race bicycle. Strangely though, they're not oriented to use the peak torque part of the pedal stroke, but actually offset at a mysterious angle. I heard psychopath and bicycle expert Lance Armstrong explain that this is actually to optimize knee speed. Apparently, the transition from the leg moving up to down is very stressful and energy sapping. By manipulating the chain ring they can mitigate peak acceleration at that point.
 — bs0u0155, Feb 13 2018

Admit it, [IT], you just like saying "epitrochoid", like you know what it means.
 — 8th of 7, Feb 14 2018

 I'm trying to imagine anywhere where an epitrochoid could feasibly be shoehorned into, and failing.

This could be because shoehorns are designed for shoes, by and large. Are you sure you wouldn't be better off with an abstract- mathematical-curve-horn?
 — Wrongfellow, Feb 14 2018

No, the concrete is what you stand on.
 — 8th of 7, Feb 14 2018

What if you used a sort of outrigged cam to drive a shoehorn so that it tried to shoehorn your foot into a shoe while you were riding a bicycle? Might one end of that shoehorn then describe an epitrochoid while at it?
 — pertinax, Feb 14 2018

No, those are cows.
 — pertinax, Feb 15 2018

Cows have shoes ? We thought that was horses...
 — 8th of 7, Feb 15 2018

It inkles.
 — pertinax, Feb 16 2018

 //just click on a camera icon and take a snap and instantly post //

 Oh. Well, if you think some form of instant-snap-talk software would be anything other than an encouragement for underemployed narcissists I suppose you could go for it.

Perhaps the aggressive opposition to change cultured 'round these parts might convince the natives to begrudgingly house the soon-to-be-destitute MS paint. It would add functionality, but only a tiny amount, and would contribute to less overall change. I for one, don't want to live in a world without the living fossil of graphics.
 — bs0u0155, Feb 16 2018

 // an encouragement for underemployed narcissists //

 [IT] would just adore that ....

 // I for one, don't want to live in a world without the living fossil of graphics. //

 Come, join us ... don't be afraid ... you'll wonder why you ever hesitated ...

And we give you a really neat head-mounted laser for dazzling non-Borg, absolutely free ... how cool is that ?
 — 8th of 7, Feb 16 2018

Geez, this was baked on my first rigid frame Costco (ahem, Price Club) mountain bike in 1988.
 — normzone, Feb 17 2018

Now an elliptical gear that changed it's tooth number, in a compact form factor, would be on the want list.
 — wjt, Feb 17 2018

 Ooh, epitrochoid is a good word.

 Circles outside of circles inside of circles around circles between circles through circles in a circle.

It's totally tubular to the max.
 — 2 fries shy of a happy meal, Feb 20 2018

 //Now an elliptical gear that changed it's tooth number, in a compact form factor, would be on the want list//

Maybe 3 chainrings stacked? Say 22-32-42 teeth. 35+50+70 grams or so for the stack? Well under 200g handling maybe 200lb/ft of torque? Shame it already exists. I learned long ago that the bicycle is about as perfect a machine as exists. It's simple enough that anyone with engineering skills can enter the market, there's enough enthusiasts for exotic development and billions of people demanding them for transport. They're almost perfect. Provided you ignore all the frivolous developments that took place after the Raleigh Sports
 — bs0u0155, Feb 20 2018

No sorry, imagining a shapeshifting nanobot composite cog with torque sensing abilities that clicks like a swarm of bees.
 — wjt, Feb 21 2018

 ^ [marked-for-tagline]

 // clicks like a swarm of bees. //

Sounds likely to jam up.
 — 8th of 7, Feb 21 2018

Software glitches do happen occasionally. Just don't reboot while riding.
 — wjt, Feb 22 2018

 //torque sensing abilities that clicks like a swarm of bees.//

I see I'm not the only one to have experience of the wonders of mid 90's British engineering. The Hope TiGlide fulfilled every facet of best practice in recent British engineering, beautiful, expensive to buy, expensive to service with irritating features. <link>
 — bs0u0155, Feb 22 2018

 Odd link ... we thought it would be to the Typhoon ....

After all, you did say // every facet of best practice in recent British engineering, beautiful, expensive to buy, expensive to service with irritating features. //
 — 8th of 7, Feb 22 2018

Ehhhh shouldn’t this be gone by now, given that it’s totally baked and widely known to already exist. I'm throwing this bone at it begin the process. {-}
 — xenzag, Feb 22 2018

 //Ehhhh shouldn’t this be gone by now, given that it’s totally baked and//

 Well, the ORIGINAL purpose of the idea has become somewhat redundant. There's been a little mission creep and in the absence of a common goal individuals have very much switched to their own agendas. For political purposes, we're all still very much committed to our goals and would like to request additional funding to cover the expenses that arise with the creation of a more inclusive and diverse goal sphere. Many goals are so diverse as to be diametrically opposed, as such tremendous resources are needed to ensure balance.

My personal goals revolve around thinking up something funny about the Eurofighter and the engineering thereof. Once achieved, I'm happy to consider alternative motions until the steering committee is convened regarding the selection of AGM location (Tuscany) and Christmas party booze budget.
 — bs0u0155, Feb 22 2018

 // a more inclusive and diverse goal sphere. Many goals are so diverse as to be diametrically opposed, as such tremendous resources are needed to ensure balance. //

 It's very unwise to make such a sweeping statement without first having a properly constituted Goal Diversity Diversity Review Working Party to examine and report on the issues. While the majority of the work can probably be office-based (suites at a five-star hotel and a conference room for the delegates would be adequate), obviously a fair amount of field work will unfortunately be required. We understand that locations such as Monte Carlo, Antibes and the Sorrento area provide a suitable amount of cutural diversity during the winter months of the northern hemisphere; a great saving can therefore be achieved by chartering a moderately sized cruise liner for the use of the field team, being able to deliver both transport, working space and accomodation in one economical unit.

 We suggest an advance inspection group is sent to Tuscany to inspect potential venues. A proper entertainment budget can't be determined until the exact parameters of the event itself have been defined. That will require the report of the beverage selection working party to be signed off ... which may take some time.

All that's needed is for [xen] to forward a Letter of Intent with regard to open-ended funding of the work.
 — 8th of 7, Feb 22 2018

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