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How many cogs of each can you should you use?



 
 
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  #1  
Old June 7th 14, 09:46 AM posted to rec.bicycles.tech
Sir Ridesalot
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Default How many cogs of each can you should you use?

Back in the days of 10 gears bicycles it was recommended due to chain deflection and duplicate gears that you not use the big big or small small combinations of cog and chainring. How many cogs-chainring combos is it recommended to not use on 9 speeds, 10 speeds and 11 speeds rear clusters?

Cheers
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  #2  
Old June 7th 14, 12:22 PM posted to rec.bicycles.tech
Duane[_4_]
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Default How many cogs of each can you should you use?

Sir Ridesalot wrote:
Back in the days of 10 gears bicycles it was recommended due to chain
deflection and duplicate gears that you not use the big big or small
small combinations of cog and chainring. How many cogs-chainring combos
is it recommended to not use on 9 speeds, 10 speeds and 11 speeds rear clusters?

Cheers


Some time it's not possible to use them all depending on the cage. I have
a short cage with a 53/39 11-28 set up. It won't shift to the big-big if
it's set to take the slack on the small-small.

--
duane
  #3  
Old June 7th 14, 12:45 PM posted to rec.bicycles.tech
[email protected]
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Default How many cogs of each can you should you use?

6. Count up from the bottom cog then subtract 30% cog inches relative to the CR/rear cog average ratio.
  #4  
Old June 7th 14, 01:35 PM posted to rec.bicycles.tech
Lou Holtman[_5_]
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Default How many cogs of each can you should you use?

On Saturday, June 7, 2014 10:46:24 AM UTC+2, Sir Ridesalot wrote:
Back in the days of 10 gears bicycles it was recommended due to chain deflection and duplicate gears that you not use the big big or small small combinations of cog and chainring. How many cogs-chainring combos is it recommended to not use on 9 speeds, 10 speeds and 11 speeds rear clusters?



Cheers


Technically you can use all combinations, but I think the chain runs awful on the two outer most cogs. I also think the chain runs awful on a 11 and 12 tooth cog even when on the big chainring. It is a trade off between, wear, efficiency, noise and speed of getting into the right gear.

Lou
  #5  
Old June 7th 14, 03:33 PM posted to rec.bicycles.tech
JBeattie
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Default How many cogs of each can you should you use?

On Saturday, June 7, 2014 5:35:37 AM UTC-7, Lou Holtman wrote:
On Saturday, June 7, 2014 10:46:24 AM UTC+2, Sir Ridesalot wrote:

Back in the days of 10 gears bicycles it was recommended due to chain deflection and duplicate gears that you not use the big big or small small combinations of cog and chainring. How many cogs-chainring combos is it recommended to not use on 9 speeds, 10 speeds and 11 speeds rear clusters?








Cheers




Technically you can use all combinations, but I think the chain runs awful on the two outer most cogs. I also think the chain runs awful on a 11 and 12 tooth cog even when on the big chainring. It is a trade off between, wear, efficiency, noise and speed of getting into the right gear.



Lou


And I think the small-small(39/12)is particularly bad on my CX/commuter bike which has 135mm spacing and a slightly greater chain angle.

I try to avoid big-big just because when the hill really gets steep and I have to down shift, over shift can occur.

-- Jay Beattie.
  #6  
Old June 7th 14, 04:21 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Default How many cogs of each can you should you use?

On 6/7/2014 4:46 AM, Sir Ridesalot wrote:
Back in the days of 10 gears bicycles it was recommended due to chain deflection

and duplicate gears that you not use the big big or small small
combinations of cog
and chainring. How many cogs-chainring combos is it recommended to not
use on 9 speeds,
10 speeds and 11 speeds rear clusters?

First, I don't think the advice against big-big and small-small combos
had much to do with duplicate gears. I think the main idea was to
protect the chain from excessive lateral bending, which would probably
induce more friction loss at the side plates. IOW, less efficiency.

But modern chains are more flexible than those of the 10 speed days (the
1970s), so I think that's much less of a worry. Generally, the penalty
for angling the chain is minor.

There may be exceptions. My touring bike still has "half-step + granny"
chainrings (something like 52 - 47 - 24 teeth). Putting it in the
small-small gear has the chain almost scraping the side of the 47 tooth
ring. I suppose on some bikes, you might get interference there
(although nobody needs half-step+granny with 9 cogs). And as Duane said,
on some bikes you might run out of chain or run out of derailleur capacity.

Absent such obvious problems, I don't worry about it much. With 9 cogs,
you can get any reasonable gear with a pretty straight chain line; but
IME if you have the chain bent a bit further, it does no real harm.

--
- Frank Krygowski
  #7  
Old June 7th 14, 04:46 PM posted to rec.bicycles.tech
Lou Holtman[_5_]
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Default How many cogs of each can you should you use?

On Saturday, June 7, 2014 4:33:46 PM UTC+2, jbeattie wrote:
On Saturday, June 7, 2014 5:35:37 AM UTC-7, Lou Holtman wrote:

On Saturday, June 7, 2014 10:46:24 AM UTC+2, Sir Ridesalot wrote:




Back in the days of 10 gears bicycles it was recommended due to chain deflection and duplicate gears that you not use the big big or small small combinations of cog and chainring. How many cogs-chainring combos is it recommended to not use on 9 speeds, 10 speeds and 11 speeds rear clusters?
















Cheers








Technically you can use all combinations, but I think the chain runs awful on the two outer most cogs. I also think the chain runs awful on a 11 and 12 tooth cog even when on the big chainring. It is a trade off between, wear, efficiency, noise and speed of getting into the right gear.








Lou




And I think the small-small(39/12)is particularly bad on my CX/commuter bike which has 135mm spacing and a slightly greater chain angle.



I try to avoid big-big just because when the hill really gets steep and I have to down shift, over shift can occur.



-- Jay Beattie.


True. At the end of this month we plan to cross the Alpes. For that I mounted a 10 speed 12-30 cassette on my triple equipped bike. Since this is at the edge of my medium caged RD I test rode it first yesterday in the Dutch 'mountains'. I had to ride 110 km to get 1650 meters elevation gain but enough steep hills to test all my gears. On the small chainring (30T) the three smallest cogs shift very sloppy. On the big chainring the three largest cogs tend to overshift and at one time the the chain fell of the big cog and went on again in a bumpy corner. In the middle ring (42T) it all went well what makes this cassette a real nice one on the flats. I can stay in the middle ring all the time although 42/12 doesn't sound/feel nice.

Lou
  #8  
Old June 7th 14, 06:23 PM posted to rec.bicycles.tech
[email protected]
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Default How many cogs of each can you should you use?

Not sure I follow any official rules. I do not use the big chainring much. So using the big-big combinations is of no concern to me. Once a month I might be near a big-big combination. I do use the small-small combinations quite a bit. Have not noticed any problems and I can usually adjust the front derailleur to eliminate any noise. When using a triple crankset I only use the inner chainring with the biggest couple cogs.
  #9  
Old June 7th 14, 10:44 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Default How many cogs of each can you should you use?

On 6/7/2014 11:46 AM, Lou Holtman wrote:


True. At the end of this month we plan to cross the Alpes.

For that I mounted a 10 speed 12-30 cassette on my triple equipped bike.
Since this is at the edge of my medium caged RD I test rode it first
yesterday in the Dutch 'mountains'. I had to ride 110 km to get 1650
meters elevation gain but enough steep hills to test all my gears.
On the small chainring (30T) the three smallest cogs shift very sloppy.
On the big chainring the three largest cogs tend to overshift and at
one time the the chain fell of the big cog and went on again in a bumpy
corner. In the middle ring (42T) it all went well what makes this cassette
a real nice one on the flats. I can stay in the middle ring all the time
although 42/12 doesn't sound/feel nice.

Our most extreme chain angles happen on our Bike Fridays. Because of
the 20" wheels, we normally ride on the big chainring; otherwise we'd be
putting lots of wear on the tiniest rear cogs. And those special 9 and
10 tooth rear cogs feel pretty rough, anyway.

When downshifting for a hill, we could move to the middle chainring, and
often we do that. But from time to time, we'll be in the big ring and
the big rear cog. I think that's part of the reason the shifting is
sometimes not perfect. There have been times I've been glad to have
bar-end shifters with a friction option.

BTW, my wife's Friday was shifting badly last week. It appeared the
rear derailleur hanger was a bit bent, so I removed the derailleur and
straightened the hanger. Upon reassembly, I had to play with the "B"
screw quite a while to prevent the derailleur body from scraping on the
chainstay! (The chainstay and seatstay on these bikes is one tube, bent
into a sort of "U" shape.)

--
- Frank Krygowski
  #10  
Old June 7th 14, 11:08 PM posted to rec.bicycles.tech
Joe Riel
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Posts: 1,071
Default How many cogs of each can you should you use?

Frank Krygowski writes:

On 6/7/2014 11:46 AM, Lou Holtman wrote:


True. At the end of this month we plan to cross the Alpes.

For that I mounted a 10 speed 12-30 cassette on my triple equipped bike.
Since this is at the edge of my medium caged RD I test rode it first
yesterday in the Dutch 'mountains'. I had to ride 110 km to get 1650
meters elevation gain but enough steep hills to test all my gears.
On the small chainring (30T) the three smallest cogs shift very sloppy.
On the big chainring the three largest cogs tend to overshift and at
one time the the chain fell of the big cog and went on again in a bumpy
corner. In the middle ring (42T) it all went well what makes this cassette
a real nice one on the flats. I can stay in the middle ring all the time
although 42/12 doesn't sound/feel nice.

Our most extreme chain angles happen on our Bike Fridays. Because of
the 20" wheels, we normally ride on the big chainring; otherwise we'd
be putting lots of wear on the tiniest rear cogs. And those special 9
and 10 tooth rear cogs feel pretty rough, anyway.


The Moulton also has a 9 tooth cog. It kind of made sense with the
52/42 chainrings that came with the bike, but I now use a 63/52. Not
sure it was ever any faster than a bigger cog---it feels awfully lossy.


--
Joe Riel
 




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