Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

User Tag List

Reply
 
Thread Tools Search this Thread
Old 01-23-08, 03:07 PM   #1
alfiegee
Senior Member
Thread Starter
 
Join Date: Jul 2007
Bikes:
Posts: 71
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
does any make a 23 tooth cog?

other than soma? if not I'm probably just gonna have to get a 22 tooth
alfiegee is offline   Reply With Quote
Old 01-23-08, 03:10 PM   #2
el twe
crotchety young dude
 
el twe's Avatar
 
Join Date: Jan 2005
Location: SF, CA
Bikes: IRO Angus; Casati Gold Line; Redline 925; '72 Schwinn Olympic Paramount
Posts: 4,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I doubt it. Why not get the Soma?

And what the hell chainring do you have?
__________________
Quote:
Originally Posted by CardiacKid View Post
I explained that he could never pay me enough cash for the amount of work I had put into that bike and the only way to compensate me for it was to ride the hell out of it.
IRO Angus Casati Gold Line
el twe is offline   Reply With Quote
Old 01-23-08, 03:12 PM   #3
dijos
Walks with a limp
 
dijos's Avatar
 
Join Date: Nov 2006
Location: St Pete
Bikes:
Posts: 1,341
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
what's wrong with the soma? plus, 52t ring?
dijos is offline   Reply With Quote
Old 01-23-08, 03:13 PM   #4
alfiegee
Senior Member
Thread Starter
 
Join Date: Jul 2007
Bikes:
Posts: 71
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've just been reading that the soma's aren't that good..I'm running 48/19 right now..just looking for something a little tougher.
alfiegee is offline   Reply With Quote
Old 01-23-08, 03:23 PM   #5
lildave
dumps like a truck
 
Join Date: May 2005
Location: Richmond, VA
Bikes: bridgestone 400 fixed conversion, khs aero track, specialized crossroads rebuilt with ultegra 105 and xt
Posts: 45
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
A 23 tooth cog will not be tougher. Unless I'm not grasping what you mean by "tougher".
lildave is offline   Reply With Quote
Old 01-23-08, 03:25 PM   #6
pirate
Senior Member
 
pirate's Avatar
 
Join Date: Apr 2006
Bikes:
Posts: 978
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
uh, if you want a tougher gear ratio, you need a smaller cog, not a bigger one.

doh, this guy beat me to it

maybe he's trying to develop a super-tough spin.
pirate is offline   Reply With Quote
Old 01-23-08, 03:30 PM   #7
alfiegee
Senior Member
Thread Starter
 
Join Date: Jul 2007
Bikes:
Posts: 71
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?
alfiegee is offline   Reply With Quote
Old 01-23-08, 03:30 PM   #8
babychris
sharkfin.
 
babychris's Avatar
 
Join Date: Jul 2006
Location: philllaaaaay.
Bikes: davidson track. landshark
Posts: 1,691
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by alfiegee View Post
wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?
lol.
babychris is offline   Reply With Quote
Old 01-23-08, 03:43 PM   #9
el twe
crotchety young dude
 
el twe's Avatar
 
Join Date: Jan 2005
Location: SF, CA
Bikes: IRO Angus; Casati Gold Line; Redline 925; '72 Schwinn Olympic Paramount
Posts: 4,818
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Those MASH dudes run pretty big gears. You ever watch the parts where they just spin through traffic downhill? That's 75+ inches.
__________________
Quote:
Originally Posted by CardiacKid View Post
I explained that he could never pay me enough cash for the amount of work I had put into that bike and the only way to compensate me for it was to ride the hell out of it.
IRO Angus Casati Gold Line
el twe is offline   Reply With Quote
Old 01-23-08, 03:47 PM   #10
kidtwisty
Track Tricyclist
 
kidtwisty's Avatar
 
Join Date: Aug 2007
Location: bay area
Bikes:
Posts: 546
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by alfiegee View Post
wouldn't lower gear inches make it easier to skid and what nots? I heard the guys from mash run 42/20 or something like that which gives them gear inches of 55.3..? right? I dunno?
right. and you said you wanted your ride to be tougher.
how would being able to skid more easily equate to this?
kidtwisty is offline   Reply With Quote
Old 01-23-08, 04:04 PM   #11
Cynikal
Team Beer
 
Cynikal's Avatar
 
Join Date: Apr 2004
Location: Sacramento CA
Bikes: Too Many
Posts: 5,925
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
I think he is referring to the quality of the cog folks.
Cynikal is offline   Reply With Quote
Old 01-23-08, 05:20 PM   #12
mihlbach
Senior Member
 
mihlbach's Avatar
 
Join Date: Dec 2005
Location: Long Island, NY
Bikes:
Posts: 6,400
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
You have nothing to worry about with Soma cogs. I've used about every brand of fixed cog available, and Soma's are basically just as good as EAI, Surly, Dura ace, and Miche cogs.
mihlbach is offline   Reply With Quote
Old 01-23-08, 05:38 PM   #13
Ken Cox
King of the Hipsters
 
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
Posts: 2,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

I presently ride at 59 gear inches.

For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
At some point, though, the increased weight negates the increased smoothness/efficiency.

Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).

Last edited by Ken Cox; 01-23-08 at 06:08 PM.
Ken Cox is offline   Reply With Quote
Old 01-23-08, 05:46 PM   #14
conor
Senior Member
 
Join Date: Jul 2007
Bikes:
Posts: 685
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
can you explain the mathematics?
conor is offline   Reply With Quote
Old 01-23-08, 06:10 PM   #15
Ken Cox
King of the Hipsters
 
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
Posts: 2,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by conor
can you explain the mathematics?
Let me find the book.

I have right here in plain view, somewhere.
Ken Cox is offline   Reply With Quote
Old 01-23-08, 06:32 PM   #16
Hocam
Ho-Jahm
 
Hocam's Avatar
 
Join Date: Nov 2006
Location: Manchester, NH
Bikes:
Posts: 4,228
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Seems like more contact area with more teeth, but each link is bending fewer degrees as it travels around the cog.
Hocam is offline   Reply With Quote
Old 01-23-08, 07:09 PM   #17
mihlbach
Senior Member
 
mihlbach's Avatar
 
Join Date: Dec 2005
Location: Long Island, NY
Bikes:
Posts: 6,400
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Ken Cox View Post
I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

I presently ride at 59 gear inches.

For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
At some point, though, the increased weight negates the increased smoothness/efficiency.

Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).
Ken, your babble about prime numbers, gear inches, and tooth counts does not explain what was wrong with your Soma cog. A lot of people claim the EAI is better, but most people just repeat what they hear without actually perceiving any real differences. I can't honestly tell any difference between my Soma 17t cog and my EAI 17t cog*. Perhaps if I was on a smooth wooden track and had years and years of racing experience. But whatever minute differences that exist between these cogs don't matter on the road...all that really matters (aside from gear ratio obviously) is that the cog doesn't strip the hub, is reasonably quite, and doesn't wear too fast. They (EAI, Soma, Surly, etc.) all perform about the same on those terms.

edit: *I'm talking about the basic EAI cog, not the gold super($$)cog, which I have never used.

Last edited by mihlbach; 01-23-08 at 07:54 PM.
mihlbach is offline   Reply With Quote
Old 01-23-08, 07:29 PM   #18
operator
cab horn
 
Join Date: Jun 2004
Location: Toronto
Bikes: 1987 Bianchi Campione
Posts: 28,306
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Ken Cox View Post
I've used a number of different cogs, too, with the exception of Phil Wood's cogs, and, to me, EAI cogs seem the best, by far, and Soma...well...I didn't like my Soma cog.

I have a thing about prime numbers, and in terms of cogs and chain rings, that means 13, 17, 19, 23, 43, 47, and 53 teeth.

This winter, I've also discovered the charm of riding at a much lower gear inch than I had ever anticipated.

I presently ride at 59 gear inches.

For those not familiar with gear inches, the typical factory fixie, with a 16t cog and a 48t ring, has about 78 gear inches.

I've ridden has high as 82 gear inches, and I need to ride at 72 gear inches or below in order to ride without a brake (I always ride with a front brake).

Further, I have always intuited that the greater the number of teeth in total, the more mechanical efficiency one experiences.
I couldn't prove this until just recently, when I picked up a book on mathematical proofs and the book addressed this very subject.

At any given gear inch, the more teeth one has, the more mechanical efficiency, or smoothness, if one wants to think of it this way.
At some point, though, the increased weight negates the increased smoothness/efficiency.

Anyway, I have 53 tooth chainring that I like, and I ride it with a 19 tooth cog.

How cool if I had a 23 tooth cog, for 60 gear inches and 23 skid patches (even though I don't skid).
Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

The bigger your cogs/chainrings the longer they will last.
operator is offline   Reply With Quote
Old 01-23-08, 07:36 PM   #19
knucks
Senior Member
 
Join Date: Mar 2007
Bikes:
Posts: 706
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by operator View Post

The bigger your cogs/chainrings the longer they will last.
sounds bout right...
knucks is offline   Reply With Quote
Old 01-23-08, 07:37 PM   #20
mihlbach
Senior Member
 
mihlbach's Avatar
 
Join Date: Dec 2005
Location: Long Island, NY
Bikes:
Posts: 6,400
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by operator View Post
Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

The bigger your cogs/chainrings the longer they will last.
Even if more a few more teeth (but with the same ratio) is more efficient in some way (less friction?), the effect of adding a few teeth to your chainring and cog would be so minor that it would be basically irrelevant.

Last edited by mihlbach; 01-23-08 at 07:53 PM.
mihlbach is offline   Reply With Quote
Old 01-23-08, 07:46 PM   #21
wroomwroomoops
Sir Fallalot
 
wroomwroomoops's Avatar
 
Join Date: Jul 2006
Location: Helsinki, Finland
Bikes:
Posts: 5,275
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by operator View Post
Mechanical efficiency with more teeth? Sorry, that doesn't make sense. If anything, the longer your chain the less efficient it is.

The bigger your cogs/chainrings the longer they will last.
I read about this somewhere (Sheldon Brown-ish no-bull**** place), that smaller chainrings and sprockets will cause more stress on the chain and as a result, higher friction losses.

Then there's that paper in "Human Power" that compared various gear systems - among them deraileur-equipped systems, and compared the transmission losses for various sprocket-chainring combinations. Even there, there was a trend to have higher efficiency (closer to 100%) with larger sprocket+chainring, although by no means a linear function.
wroomwroomoops is offline   Reply With Quote
Old 01-23-08, 10:32 PM   #22
Ken Cox
King of the Hipsters
 
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
Posts: 2,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by mihlbach
Ken, your babble about prime numbers, gear inches, and tooth counts does not explain what was wrong with your Soma cog.
Babble, eh?

How nice.

That kind of talk just endears me to people.

Maybe we could have dinner some time.

In any event, I had some reluctance to name the Soma cog, because I might have gotten a bad one, and it seems wrong to take away from someone's livelihood over a chance event...and a lot of people read this forum.

Anyway, I had an out of round cog from Soma.

How could that happen?

Certainly not because Soma doesn't try to market round cogs.

I think an anomaly somehow slipped through the process.

I would think a computer makes these things, and computers never make mistakes, right?

In any event, just handling the various makes of cogs, the EAI cogs feel and look like higher quality.

Subjective, I know, but very real to me.

I regularly handle high-end machined parts, and the EAI cogs have that look and feel.

=====

Now I'll get a letter from Soma's attorneys telling me to either produce the allegedly out-of-round cog or retract my statement.

Can I shortcut the process by retracting my statement before I make it?

Post Script: I'll find the book that had explanation of the efficiency of greater numbers of teeth; actually, combined radii.

Last edited by Ken Cox; 01-23-08 at 10:35 PM. Reason: After thought.
Ken Cox is offline   Reply With Quote
Old 01-23-08, 11:23 PM   #23
Ken Cox
King of the Hipsters
 
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
Posts: 2,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Well, I couldn't find the book, so I did an Internet search.

I couldn't find one site that had the complete answer, but I'll just combine some of them.

I still haven't found the proof I want.

=====

For any given gear ratio, say 2:1, many different gear diameters and numbers of teeth will work, as long as they have a ratio of 2:1.

However, as the diameter of the gear pairs increase, the chain remains more straight as it reverses direction, and thus, each chain segment bends less.

As each chain segment bends less, the entire drive train system experiences less "chain segment bending loss."

One can further reduce chain segment bending loss, which involves not only the interaction between the pins and bushings, but the interaction between the pins and bushings and the faces of the gear teeth as well.

The straighter the chain stays, or the larger the "corner" it turns, the less chain segment bending loss.

Additionally, one can further reduce chain segment bending loss by replacing the bushings with bearings, so that the meeting surfaces between the gear teeth and the chain experience no friction.

The so-called bushings of high-end 1/8" track chains correspond to bearings rather than bushings.

At some point, the combined weight of the larger diameter gears and the more complex chain undoes the advantages of bearing surfaces between chain and gear teeth, and a straighter, less-bent chain.

Where do the two curves cross?

I don't know.

However, somewhere between a small chain ring and cog combo and a large chain ring and cog combo; and somewhere between the simplest lightest 3/32" bushingless chain, and the heaviest, most complex chain with bushings/bearings, lies the optimum in terms of minimal friction, bending loss, and weight.

Last edited by Ken Cox; 01-23-08 at 11:25 PM. Reason: typo
Ken Cox is offline   Reply With Quote
Old 01-23-08, 11:30 PM   #24
Johnny Nemo
Senior Member
 
Johnny Nemo's Avatar
 
Join Date: Sep 2007
Location: Woolloomooloo, Australia
Bikes: A fixed gear, a vintage roadie and a POS.
Posts: 415
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I don't think they make a 23 (for 23 non skidding patches), but maybe you could get a (non prime) 24?!
Johnny Nemo is offline   Reply With Quote
Old 01-23-08, 11:47 PM   #25
Ken Cox
King of the Hipsters
 
Join Date: Jan 2005
Location: Bend, Oregon
Bikes: Realm Cycles Custom
Posts: 2,129
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Check out this site:

http://www.gizmology.net/sprockets.htm

It explains chain design and how the engineers design the profile of the teeth for a given size sprocket.

This site corrects a misconception I had about chain bushings:

http://chain-guide.com/applications/...cle-chain.html

Very good drawings.
Ken Cox is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 05:54 PM.