Gear Calculator
03-15-07 | 12:45 PM
#26
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
The Java Web Start (jnlp) launcher was causing some mac people issues so I added an applet version.
Check it out at:
https://software.bareknucklebrigade.com/
tt
Check it out at:
https://software.bareknucklebrigade.com/
tt
03-15-07 | 04:13 PM
#27
Senior Member
Joined: Sep 2006
Posts: 3,744
Likes: 1
From: Van BC
Sufferin succotash, it works!
3 cheers for testtube
This program is great, I really like how no-frills it is and the instant response. All the others I've used require hitting a Run button after tweaking settings.
3 cheers for testtube
This program is great, I really like how no-frills it is and the instant response. All the others I've used require hitting a Run button after tweaking settings.
03-15-07 | 04:16 PM
#28
Wolfman got nards!
Joined: Jan 2006
Posts: 601
Likes: 1
From: Denver, CO
Bikes: '06 Bianchi Volpe, '09 Mercier Kilo TT, '08 Jamis Exile 29er
Originally Posted by mander
Sufferin succotash, it works!
3 cheers for testtube
3 cheers for testtube
__________________
.
Reason is a scoundrel, stupidity is direct and honest. –Ivan Fyodorovich Karamazov
Man's mind, once stretched by a new idea, never regains its original dimensions. –Oliver Wendell Holmes
.
Reason is a scoundrel, stupidity is direct and honest. –Ivan Fyodorovich Karamazov
Man's mind, once stretched by a new idea, never regains its original dimensions. –Oliver Wendell Holmes
03-16-07 | 06:53 PM
#32
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
linked from sheldonbrown.com... woo!
https://sheldonbrown.com/gears
https://sheldonbrown.com/fixed
Again... Let me know if you want any features or have ideas for other software... eh. i wish i had my SS/FG so i could spend more time on riding as opposed to writing software...
tt
https://sheldonbrown.com/gears
https://sheldonbrown.com/fixed
Again... Let me know if you want any features or have ideas for other software... eh. i wish i had my SS/FG so i could spend more time on riding as opposed to writing software...
tt
03-17-07 | 08:59 PM
#33
Originally Posted by testtube
I wrote up a SS/FG gear calculator. Attached is a screen shot...
I'm new to the SS/FG thing so I put this together to help me understand what gearing I wanted...
If you have Java installed you should be able to click on the link below to run it...
https://rabbit.bareknucklebrigade.com/rabbit.jnlp
If you want features added let me know...
tt
I'm new to the SS/FG thing so I put this together to help me understand what gearing I wanted...
If you have Java installed you should be able to click on the link below to run it...
https://rabbit.bareknucklebrigade.com/rabbit.jnlp
If you want features added let me know...
tt
__________________
So long. Been nice knowing you BF.... to all the friends I've made here and in real life... its been great. But this place needs an enema.
So long. Been nice knowing you BF.... to all the friends I've made here and in real life... its been great. But this place needs an enema.
03-19-07 | 10:00 PM
#34
Stinky McStinkface
Joined: Aug 2006
Posts: 943
Likes: 0
From: Pa.
Bikes: Clemente Custom(not built-up), TI Raleigh Record SS, VitaSprint Mixte SS, IRO S.E.(coming) Ibex Trophy Pro
sorry to go off thread topic... I remember there was thread about cog/chainring setups... opinions about odd/even teeth... does anyone remember which one it was?
__________________
Because, yeah... uh huh! Umm, yeah!
Because, yeah... uh huh! Umm, yeah!
03-19-07 | 10:12 PM
#35
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
I don't know about the original thread but from perusing Sheldon Brown's fixed gear site...
ring / cog tooth count :
- odd / odd (simplified ratio) good for increasing skid patch count
- even / even good for extending chain life
https://software.bareknucklebrigade.com/
ring / cog tooth count :
- odd / odd (simplified ratio) good for increasing skid patch count
- even / even good for extending chain life
https://software.bareknucklebrigade.com/
03-19-07 | 10:22 PM
#36
Stinky McStinkface
Joined: Aug 2006
Posts: 943
Likes: 0
From: Pa.
Bikes: Clemente Custom(not built-up), TI Raleigh Record SS, VitaSprint Mixte SS, IRO S.E.(coming) Ibex Trophy Pro
how about an odd/even or even/odd combo? how does that affect this?
__________________
Because, yeah... uh huh! Umm, yeah!
Because, yeah... uh huh! Umm, yeah!
03-19-07 | 11:16 PM
#37
Senior Member
Joined: Sep 2006
Posts: 3,744
Likes: 1
From: Van BC
https://www.bikeforums.net/singlespeed-fixed-gear/242123-skid-patch-theorem.html
This theorem has it that only the numerator of the chainring teeth/ cog teeth fraction affects whether ambidextrous skidding doubles the number of skid patches. This is contrary to how Rabbit calculates this (it assumes that both the numerator and the deniminator must be odd), and to what Sheldon says (that only the deniminator must be odd). The proof looks right to me but I suck at numbers and am lazy. Can anyone tell me if it is correct?
Here it is:
This theorem has it that only the numerator of the chainring teeth/ cog teeth fraction affects whether ambidextrous skidding doubles the number of skid patches. This is contrary to how Rabbit calculates this (it assumes that both the numerator and the deniminator must be odd), and to what Sheldon says (that only the deniminator must be odd). The proof looks right to me but I suck at numbers and am lazy. Can anyone tell me if it is correct?
Here it is:
Originally Posted by fraction
Let a / b be the reduced gear ratio (that is, a and b are integers with no common divisors other than 1). Then,
...
(2) Ambidexterous skidding doubles the number of skid patches if and only if a is odd.
...
Proof of (2):
As above, turning the pedals through one revolution turns the rear wheel through a / b revolutions. Turning the pedals through one half-revolution turns the rear wheel through half as many revolutions. So the number of skid patches with ambidexterous skidding should be the same as that with single-sided skidding on a gear ratio half as large. Now to apply (1) to this situation, we need to know how 1/2 * a/b reduces as an integer ratio. This depends on whether a is even or odd. If a is even, (a/2) / b is the reduced ratio, so there are b skid patches, as in the single-sided case. If a is odd, a / (2b) is the reduced ratio, so there are 2b skid patches.
...
(2) Ambidexterous skidding doubles the number of skid patches if and only if a is odd.
...
Proof of (2):
As above, turning the pedals through one revolution turns the rear wheel through a / b revolutions. Turning the pedals through one half-revolution turns the rear wheel through half as many revolutions. So the number of skid patches with ambidexterous skidding should be the same as that with single-sided skidding on a gear ratio half as large. Now to apply (1) to this situation, we need to know how 1/2 * a/b reduces as an integer ratio. This depends on whether a is even or odd. If a is even, (a/2) / b is the reduced ratio, so there are b skid patches, as in the single-sided case. If a is odd, a / (2b) is the reduced ratio, so there are 2b skid patches.
Last edited by mander; 03-19-07 at 11:23 PM.
03-19-07 | 11:33 PM
#38
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
Well, there may be inconsistencies with the ambi. skidding calc. on Sheldon's site...
https://www.sheldonbrown.com/fixed.html#skid
and
https://sheldonbrown.com/gloss_sa-o.html#skidpatch
I haven't found the time to sit down and break down the proof or write an algorithm to brute-force verify it... But yeah, rabbit currently uses the more restrictive of the two definitions...
tom.
https://www.sheldonbrown.com/fixed.html#skid
and
https://sheldonbrown.com/gloss_sa-o.html#skidpatch
I haven't found the time to sit down and break down the proof or write an algorithm to brute-force verify it... But yeah, rabbit currently uses the more restrictive of the two definitions...
tom.
Last edited by testtube; 03-19-07 at 11:43 PM.
It's kind of a cluster****, which is why I hope that someone who is any good at number theory will look over the proof and let me know what's what.
03-20-07 | 10:03 AM
#40
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
Just spot checked simplified chainring / sprocket ratios with a brute force skid patch calculator I wrote and Fraction is correct.
So for simplified ratios:
odd / odd -> doubles skid patch count w/ ambidextrous skidding
odd / even -> doubles skid patch count w/ ambidextrous skidding
even / odd -> does not double skid patch count w/ ambidextrous
maybe i'll write up a little applet with pics 'n all.
Rabbit has been updated to reflect the results of Fraction's skid patch theorem.
So for simplified ratios:
odd / odd -> doubles skid patch count w/ ambidextrous skidding
odd / even -> doubles skid patch count w/ ambidextrous skidding
even / odd -> does not double skid patch count w/ ambidextrous
maybe i'll write up a little applet with pics 'n all.
Rabbit has been updated to reflect the results of Fraction's skid patch theorem.
Last edited by testtube; 03-20-07 at 10:09 AM.
03-20-07 | 05:40 PM
#42
Amferny
Joined: Nov 2006
Posts: 142
Likes: 0
From: San Francisco
Bikes: 88 Cannondale M500 SS, 86 C'dale R300, 96 C'dale R400, 1966 Hercules 3spd
Does chainstay length have any thing to do with this? I don't see it as an option. But I do like how nice and easy the calculator is to use.
03-20-07 | 06:05 PM
#43
Senior Member
Joined: Sep 2006
Posts: 3,744
Likes: 1
From: Van BC
Originally Posted by 50 tooth Cannon
Does chainstay length have any thing to do with this? I don't see it as an option. But I do like how nice and easy the calculator is to use.
Last edited by mander; 03-20-07 at 06:12 PM.
03-23-07 | 11:31 PM
#44
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
Rabbit now has a skid patch analysis tool to help clear up confusion regarding the correct skid patch count calculation. This tool shows that Fraction's theorem is correct (https://www.bikeforums.net/showthread.php?t=242123).
I'll admit it's a little overkill but i think i've added it in a way that doesn't over complicate the existing functionality...
https://software.bareknucklebrigade.com
I'll admit it's a little overkill but i think i've added it in a way that doesn't over complicate the existing functionality...
https://software.bareknucklebrigade.com
03-25-07 | 09:54 AM
#46
Just a thought.
Joined: Sep 2004
Posts: 21
Likes: 0
From: Chicago, IL
Bikes: * Ciöcc MOCKBA '80, Giant Kronos, Specialized Rockhopper, Battaglin, Motobecane Grand Touring, Italvega, Bridgestone T700 *subject to change without notice.
Nice little program, testtube. I like the rpm vs. speed analysis.
I've got a feature suggestion, though, if you're still taking input.
I often find myself wanting to compare various drive ratios. Say I currently have a 46x16, what would be the next higher/lower possible combination? It's usually not immediately apparent that a 49x17/43x15 would be those combinations (if my calculations are correct.) And if you throw in differing wheel sizes, etc, it gets even more complicated.
I've put together a simple gear ratio table, but would love something more interactive and a little less overwhelming.
Would it be possible to add this "next higher/lower gear" feature with maybe checkboxes to decide whether to include crank lengths & wheel sizes in the combination? It seems like you're already pretty close to this with the "equivalent gear" feature.
Keep up the good work.
I've got a feature suggestion, though, if you're still taking input.
I often find myself wanting to compare various drive ratios. Say I currently have a 46x16, what would be the next higher/lower possible combination? It's usually not immediately apparent that a 49x17/43x15 would be those combinations (if my calculations are correct.) And if you throw in differing wheel sizes, etc, it gets even more complicated.
I've put together a simple gear ratio table, but would love something more interactive and a little less overwhelming.
Would it be possible to add this "next higher/lower gear" feature with maybe checkboxes to decide whether to include crank lengths & wheel sizes in the combination? It seems like you're already pretty close to this with the "equivalent gear" feature.
Keep up the good work.
03-25-07 | 03:20 PM
#47
Senior Member
Joined: Nov 2004
Posts: 3,959
Likes: 4
From: Davis CA
Bikes: Surly Cross-Check, '85 Giant road bike (unrecogizable fixed-gear conversion
I bookmarked it. If you take it down I'll kick your ass.
Ok, maybe since I'm a first grade teacher I'll just tell your mom.
Ok, maybe since I'm a first grade teacher I'll just tell your mom.
03-26-07 | 05:05 PM
#48
Thread Starter
Senior Member
Joined: Feb 2007
Posts: 228
Likes: 0
From: Madison, WI
Nice little program, testtube. I like the rpm vs. speed analysis.
I've got a feature suggestion, though, if you're still taking input.
I often find myself wanting to compare various drive ratios. Say I currently have a 46x16, what would be the next higher/lower possible combination? It's usually not immediately apparent that a 49x17/43x15 would be those combinations (if my calculations are correct.) And if you throw in differing wheel sizes, etc, it gets even more complicated.
I've put together a simple gear ratio table, but would love something more interactive and a little less overwhelming.
Would it be possible to add this "next higher/lower gear" feature with maybe checkboxes to decide whether to include crank lengths & wheel sizes in the combination? It seems like you're already pretty close to this with the "equivalent gear" feature.
Keep up the good work.
I've got a feature suggestion, though, if you're still taking input.
I often find myself wanting to compare various drive ratios. Say I currently have a 46x16, what would be the next higher/lower possible combination? It's usually not immediately apparent that a 49x17/43x15 would be those combinations (if my calculations are correct.) And if you throw in differing wheel sizes, etc, it gets even more complicated.
I've put together a simple gear ratio table, but would love something more interactive and a little less overwhelming.
Would it be possible to add this "next higher/lower gear" feature with maybe checkboxes to decide whether to include crank lengths & wheel sizes in the combination? It seems like you're already pretty close to this with the "equivalent gear" feature.
Keep up the good work.
most of all, i want my BFSSFG IRO to show up so I can move out of theory and on to practice... who cares about skid patch count if you can't skid...
t.
