golden ratios
10-02-06 | 02:15 PM
#1
Thread Starter
#$%^&*
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golden ratios
Have been riding 44x16 in New York/Brooklyn (mostly flat, some bridges, traffic) and as I got more in shape I would like to spin a little less and push a little more, so am thinking to either add a few teeth to my 44 or change the cog to 15 teeth (or add a few teeth to both, etc). I can do the math and will have to guess how much harder I will have to pedal but I was wondering if there are ratios to avoid i.e. that don't work very well, or some other considerations besides skid patches.
In other words, for instance, 44/15 gives a slight increase in development over 44/16 but also a much higher number of skid patches (15 as opposed to 4 for 44/16). So, odd numbers seem better (i.e. 47/16 or 49/16 rather than 48/16) or are there other factors that come into play to negate that, whether these are rational or irrational... (I was referring to the 44/14 ratio - 3.14... and 7 skid patches!)
Thanks.
In other words, for instance, 44/15 gives a slight increase in development over 44/16 but also a much higher number of skid patches (15 as opposed to 4 for 44/16). So, odd numbers seem better (i.e. 47/16 or 49/16 rather than 48/16) or are there other factors that come into play to negate that, whether these are rational or irrational... (I was referring to the 44/14 ratio - 3.14... and 7 skid patches!)
Thanks.
10-02-06 | 03:19 PM
#5
META
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From: Madison, WI
Bikes: Gary Fisher Aquila (retired), Specialized Allez Sport (in parts), Cannondale R500, HP Velotechnic Street Machine, Dented Blue Fixed Gear (retired), Seven Tsunami SSFG, Specialized Stumpjumper Comp Hardtail (alloy version)
a short explaination of how many skid patches is too few/too many and how many gear inches (same) would be useful I think.
or shall I beg 'pon bend'ed knee?
please please please please please please please please please please please please please please please please please please!?
or shall I beg 'pon bend'ed knee?
please please please please please please please please please please please please please please please please please please!?
10-02-06 | 03:28 PM
#8
redonkulous
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From: West Philly
Bikes: 2001 GT GTB
Originally Posted by rustang
weird, i thought my 46/16 only gave me 1. i'm guessing that chart is assuming you can skid both ways?
10-02-06 | 03:47 PM
#9
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From: Brooklyn
Bikes: Spicer Track; Specialized Allez M4 Pro; Cannondale Jeykll 2000; Ross conversion commuter
Gear inch numbers are higher than than values I got from Sheldon Brown's calculator using 700c wheels. What gives?
The skid patch data is way helpful, methinks I'll forego the 45 tooth zen messenger in favor of a 43...
The skid patch data is way helpful, methinks I'll forego the 45 tooth zen messenger in favor of a 43...
10-02-06 | 03:59 PM
#11
Originally Posted by bitpartinyrlife
Gear inch numbers are higher than than values I got from Sheldon Brown's calculator using 700c wheels. What gives?
Gear inches are really only useful as a rough, relative measure (ie, comparing ratio to ratio), so it doesn't really matter that you're getting slightly different measurements. Measuring by gear inches also fails to take crank length into account.
m.
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10-02-06 | 04:04 PM
#12
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Originally Posted by mihlbach
It looks to me like the gear inches chart is for 27" wheels, probably with 1 1/8" tires. The inches for 700X23 will be slightly lower.
10-02-06 | 04:07 PM
#13
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From: San Francisco, CA
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Originally Posted by rustang
weird, i thought my 46/16 only gave me 1. i'm guessing that chart is assuming you can skid both ways?
10-02-06 | 04:20 PM
#14
how i roll
Joined: Aug 2006
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From: dirty
no, ive got 46/16. i had 48/16, which i knew was 1. my math is just really ****ing bad.
this is sweet though. now i can stop taking my wheel off once a week and rotating it 1/4 turn so i don't wear through it. ha.
this is sweet though. now i can stop taking my wheel off once a week and rotating it 1/4 turn so i don't wear through it. ha.
10-02-06 | 05:30 PM
#15
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From: Syracuse, NY
Bikes: Fuji Track 06, Fuji Delrey conversion
Originally Posted by rustang
no, ive got 46/16. i had 48/16, which i knew was 1. my math is just really ****ing bad.
this is sweet though. now i can stop taking my wheel off once a week and rotating it 1/4 turn so i don't wear through it. ha.
this is sweet though. now i can stop taking my wheel off once a week and rotating it 1/4 turn so i don't wear through it. ha.
You know you could also just easily divide 46 by 16 to see what comes out, and that's your ratio.
10-02-06 | 05:35 PM
#16
crotchety young dude
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From: SF, CA
Bikes: IRO Angus; Casati Gold Line; Redline 925; '72 Schwinn Olympic Paramount
Originally Posted by ka12na
You know you could also just easily divide 46 by 16 to see what comes out, and that's your ratio.
10-02-06 | 08:45 PM
#17
Bikes are Fun
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the chart refers to always skidding with the same foot forward.
to understand this, keep in mind that a full crank rotation does not equal an whole number of rotations of the wheel, so the spot in contact with the ground changes each rotation. the number of skid spots refers to the number of full crank rotations it takes to return to the original pont of contact with the ground. its all in the ratios.
to find the number of skid spots for your ratio write the number of teeth on the chainring over the number of teeth in the cog- a fraction . then simplify that fraction as much as possible. the denominator is your number of skid spots
for example my ratio 42/16 simplifies to 21/8. that means i have 8 skid spots
to understand this, keep in mind that a full crank rotation does not equal an whole number of rotations of the wheel, so the spot in contact with the ground changes each rotation. the number of skid spots refers to the number of full crank rotations it takes to return to the original pont of contact with the ground. its all in the ratios.
to find the number of skid spots for your ratio write the number of teeth on the chainring over the number of teeth in the cog- a fraction . then simplify that fraction as much as possible. the denominator is your number of skid spots
for example my ratio 42/16 simplifies to 21/8. that means i have 8 skid spots
10-02-06 | 11:54 PM
#19
LF for the accentdeprived
Joined: May 2005
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From: Budapest, Hungary
With all these mathematically challenged people on board, I'll ****ing make a fake gear inch chart that says that 44/16 is a lot harder ratio than 50/14 and that 40/20 is halfway between them etc. I'll sneak a link to it into one of these silly threads and practice my evil laugh while people try to pedal 52/12 and scratch their heads.
10-03-06 | 01:04 AM
#20
crazy keeper
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From: vancouver
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Originally Posted by mcatano
Gear inches are really only useful as a rough, relative measure (ie, comparing ratio to ratio), so it doesn't really matter that you're getting slightly different measurements. Measuring by gear inches also fails to take crank length into account.
am i wrong or am i wrong?
10-03-06 | 03:49 AM
#23
"not enough rage"
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From: Oakland
Bikes: Old ****ed up Cannondale roadie, peice o **** Gitane as a beater, and I use my Nishiki for bike camping
Originally Posted by rustang
weird, i thought my 46/16 only gave me 1. i'm guessing that chart is assuming you can skid both ways?
(46/16 breaks down to 23/8 while 48/16, to 3/1 )
10-03-06 | 03:55 AM
#24
"not enough rage"
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From: Oakland
Bikes: Old ****ed up Cannondale roadie, peice o **** Gitane as a beater, and I use my Nishiki for bike camping
Originally Posted by bitpartinyrlife
It appears you are absolutely correct. 27 by 1 1/8th, 170mm cranks according to Sheldon. Is the skid patch info the same?
10-03-06 | 03:12 PM
#25
Gone, but not forgotten
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From: Newtonville, Massachusetts
Bikes: See: https://sheldonbrown.org/bicycles
Originally Posted by paulv
Have been riding 44x16 in New York/Brooklyn (mostly flat, some bridges, traffic) and as I got more in shape I would like to spin a little less and push a little more, so am thinking to either add a few teeth to my 44 or change the cog to 15 teeth (or add a few teeth to both, etc). I can do the math and will have to guess how much harder I will have to pedal but I was wondering if there are ratios to avoid i.e. that don't work very well, or some other considerations besides skid patches.
In other words, for instance, 44/15 gives a slight increase in development over 44/16 but also a much higher number of skid patches (15 as opposed to 4 for 44/16). So, odd numbers seem better (i.e. 47/16 or 49/16 rather than 48/16) or are there other factors that come into play to negate that, whether these are rational or irrational... (I was referring to the 44/14 ratio - 3.14... and 7 skid patches!)
Thanks.
In other words, for instance, 44/15 gives a slight increase in development over 44/16 but also a much higher number of skid patches (15 as opposed to 4 for 44/16). So, odd numbers seem better (i.e. 47/16 or 49/16 rather than 48/16) or are there other factors that come into play to negate that, whether these are rational or irrational... (I was referring to the 44/14 ratio - 3.14... and 7 skid patches!)
Thanks.
and: https://sheldonbrown.com/fixed.html#skid
Sheldon "Numbers" Brown
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