Which single speed combo is most efficient?

Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Would one be better for longevity of the drivetrain than the other?

Thanks again and cheers from Peter

On 4/25/2011 3:04 AM, Sir Ridesalot wrote:
Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

More teeth, less chain articulation, more efficient.


38 chainring& 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Close enough to not really matter.


Would one be better for longevity of the drivetrain than the other?

More teeth, less wear per tooth. Bigger chain ring, less chain tension,
more chain speed.

It seems like the 15T sprocket is more typical, so you might have more
selection above & below. People seem to want to tweak that after riding
fixers a bit. "Flip-flop" hubs are also nice in that they allow a
freewheel sprocket on one side. Mine is set up that way with a slightly
lower (1T) difference on the freewheel -- handy for hillier terrain.

On Apr 25, 2:04*am, Sir Ridesalot wrote:
Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Close enough to not matter. With Peter on this one.


Would one be better for longevity of the drivetrain than the other?

More teeth and links, more wear surfaces.



Go for the microdrive if fixed gear, as 15T cogs are common. For a
freewheel setup, the macro is good. ACS Claws and splined SS cogs are
common in 20T.

On Apr 25, 6:15*am, landotter wrote:
On Apr 25, 2:04*am, Sir Ridesalot wrote:

Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Close enough to not matter. With Peter on this one.



Would one be better for longevity of the drivetrain than the other?

More teeth and links, more wear surfaces.

But more area to bear the load equals less wear and friction? I be
from a pure efficiency standpoint, the larger cog and chain ring would
be better, but in the real world it makes no difference except for
parts availability. -- Jay Beattie.

On Apr 25, 9:30*am, Jay Beattie wrote:
On Apr 25, 6:15*am, landotter wrote:







On Apr 25, 2:04*am, Sir Ridesalot wrote:

Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Close enough to not matter. With Peter on this one.

Would one be better for longevity of the drivetrain than the other?

More teeth and links, more wear surfaces.

But more area to bear the load equals less wear and friction?

Yes. Thanks for completing my thought.

*I be
from a pure efficiency standpoint, the larger cog and chain ring would
be better, but in the real world it makes no difference except for
parts availability. -- Jay Beattie.

Yup. Around here, you're very likely to find 16/17T freewheels in
stock, same goes for fixed cogs. SS mtb'ing is popular, so it's quite
normal for folks to stock 20T splined Endless Cogs.

Sir Ridesalot wrote:

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Would one be better for longevity of the drivetrain than the other?

Maximum chain drive efficiency occurs when both the drive sprocket and
the driven sprocket are at least 21 teeth in size. Measurable losses
accrue below that size, increasing asymptotically with each drop in
size below 21t. Many technically fastidious riders consider the
losses accrued by sprockets less than 13t in size to be significant,
but the threshold is arbitrary. The relative friction loss for a 13t
sprocket versus a 14t sprocket is larger than that of a 14t versus a
15t. And so forth.

So without speculating as to whether the differences between your two
prospective drivetrains are significant in your application, it is
clear that a 52/20 will be more efficient for any given chainline than
a 38/15. It will also incur less chain wear, because the chain will
be under lower tension and will work through a smaller angle of
articulation (although it will do so at a higher linear speed).

Chalo

On Apr 25, 12:04 am, Sir Ridesalot wrote:
Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Would one be better for longevity of the drivetrain than the other?

Thanks again and cheers from Peter

You gain most efficiency by spotless cleanliness and adequate
lubrication of the chain.

and 2nd, less significance.. higher grade materials,and accurate
machining
of for the sprockets and chainring ..

On Apr 25, 9:32*am, Zarniwoop wrote:
On Apr 25, 12:04 am, Sir Ridesalot wrote:



Hi there.

Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?

38 chainring & 15 cog = 68.4 gear inches

or

52 chainring and 20 cog = 70.2 gear inches

Which of these would give the easiest to maintain cadence?

Would one be better for longevity of the drivetrain than the other?

*Thanks again and cheers from Peter

You *gain most efficiency by spotless cleanliness and adequate
lubrication of the chain.

and *2nd, less significance.. higher grade materials,and accurate
machining
of *for the sprockets and chainring ..

I used to think as U on this matter. But then I remember reading a
study
referenced here @ rbt, that ran contrary to this usual thinking, a few
years
ago where it didn't seem to make much difference what U did,
including
running a dry chain. The bottom line was IIRC that bike chains &
multiple
speed cog sets are some where between ~96% to ~86% efficient
regardless of what the conditions are, which I found shocking &
somewhat
comical @ the same time.
I think the study came from Europe, JD

Sir Ridesalot wrote:
Which of these two single speed gear combos (not a fixed gear) would
be the most efficient if there is any difference in efficiency?
38 chainring & 15 cog = 68.4 gear inches
or
52 chainring and 20 cog = 70.2 gear inches
Which of these would give the easiest to maintain cadence?
Would one be better for longevity of the drivetrain than the other?



I don't think there's an answer to that. Either works.

The more popular sets, 44x17 and 46x18 are right between
your two sets at 70 and 69.

In theory, the larger set lasts longer. In practice, the
difference may not be meaningful.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Apr 25, 9:30*am, Jay Beattie wrote:

But more area to bear the load equals less wear and friction? *I be
from a pure efficiency standpoint, the larger cog and chain ring would
be better, but in the real world it makes no difference except for
parts availability. -- Jay Beattie.

If wear was linear, that would be true. What actually happens, if you
keep the peak pressure below a critical point, there is little to no
wear. Once your peak pressure point reaches the critical pressure,
wear is rapid. With 15 teeth, the pressure is spread over 7 teeth,
with 20 teeth, the pressure is spread over 9-10 teeth.

Actually, Sun Bicycles just came out with a 2 speed kickback Spider AT
with 29 inch tires for $700.