Wide Range -- 17 speeds
 

Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

I've noticed that small/small and large/large combinations are
excluded by most designers due to rear derailer jockey cage overtravel
and chain misaliagnment and have confirmed the overtravel happens on
my bicycle, while the misalignment does not since this recumbent has a
long chain line.

I fitted a "low-normal" rear derailer....

Ruling out 2 of each extreme combination, from 3x7=21 choices I now
have a "17-speed" bike with around 650% range. How peculiar. 17
speeds....

My next project, since the cables are routed bare and parallel on the
long OSS (Over Seat Steering) column, is to make two small blocks of
metal with set screws and holes to actually "lock out" those
combinations. We'll see how that goes in a follow-up post here.

'Nuff said..

Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394

Wide Range -- 17 speeds
 

On 12 Mar, 13:26, The Dougster wrote:
Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

On a recumbent the cross chaining issue is non existant. Use all gears
you can ;)

--
Adam Kadlubek

Wide Range -- 17 speeds
 

Adam Kadlubek wrote:
On 12 Mar, 13:26, The Dougster wrote:
Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

On a recumbent the cross chaining issue is non existant. Use all gears
you can ;)

On my RANS Rocket in the 62/28 combination, the "lower" pulley on the
SRAM 7.0 (long cage MTB) derailer becomes the "front" pulley with the
cage nearly parallel to the ground. If I went to an 11-32 or 11-34
cluster, the chain would either be too short for big-big or would go
slack in the small-small combination, so there is a limit, unless an
additional chain tensioning device (e.g. Easy Racers) is used.

--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll

Wide Range -- 17 speeds
 

On Mar 12, 7:59*am, Tom Sherman
wrote:
Adam Kadlubek wrote:
On 12 Mar, 13:26, The Dougster wrote:
Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

On a recumbent the cross chaining issue is non existant. Use all gears
you can ;)

On my RANS Rocket in the 62/28 combination, the "lower" pulley on the
SRAM 7.0 (long cage MTB) derailer becomes the "front" pulley with the
cage nearly parallel to the ground. If I went to an 11-32 or 11-34
cluster, the chain would either be too short for big-big or would go
slack in the small-small combination, so there is a limit, unless an
additional chain tensioning device (e.g. Easy Racers) is used.

--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll

Big + Big is 51 + 34 = 85 teeth + chainline (crankshart to drive wheel
axle).
Sml + Sml is 24 + 11 = 35 teeth + chainline (crankshart to drive wheel
axle).
Difference is 50 teeth or 25 inches, would require a 13 inch
derailer / tensioner.
No wonder my chain goes slack when I hit the bottom rear gear.

Wide Range -- 17 speeds
 

On Mar 12, 7:28*am, wrote:
On Mar 12, 7:59*am, Tom Sherman
wrote:





Adam Kadlubek wrote:
On 12 Mar, 13:26, The Dougster wrote:
Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

On a recumbent the cross chaining issue is non existant. Use all gears
you can ;)

On my RANS Rocket in the 62/28 combination, the "lower" pulley on the
SRAM 7.0 (long cage MTB) derailer becomes the "front" pulley with the
cage nearly parallel to the ground. If I went to an 11-32 or 11-34
cluster, the chain would either be too short for big-big or would go
slack in the small-small combination, so there is a limit, unless an
additional chain tensioning device (e.g. Easy Racers) is used.

--
Tom Sherman - 42.435731,-83.985007
LOCAL CACTUS EATS CYCLIST - datakoll

Big + Big is 51 + 34 = 85 teeth + chainline (crankshart to drive wheel
axle).
Sml + Sml is 24 + 11 = 35 teeth + chainline (crankshart to drive wheel
axle).
Difference is 50 teeth or 25 inches, would require a 13 inch
derailer / tensioner.
No wonder my chain goes slack when I hit the bottom rear gear.- Hide quoted text -

- Show quoted text -

Actually, it's only half that, because the chain only wraps half of
each gear.

Wide Range -- 17 speeds
 

Wide Range -- 17 speeds
 

On 12 Mar, 13:59, Tom Sherman
wrote:
On my RANS Rocket in the 62/28 combination, the "lower" pulley on the
SRAM 7.0 (long cage MTB) derailer becomes the "front" pulley with the
cage nearly parallel to the ground. If I went to an 11-32 or 11-34
cluster, the chain would either be too short for big-big or would go
slack in the small-small combination, so there is a limit, unless an
additional chain tensioning device (e.g. Easy Racers) is used.

Well. This is the issue of chain length, not cross-chaining. Besides -
40T is a sensible range for a long cage derailleur, altho rated
capacity of derailleurs need to be taken with a grain of salt for
recumbents with their odd drivetrains. For example, for my FWD
lowracer a 43T rated capacity der could only handle 61/44 with 11-30
cassette (which is 35T difference).

Regards
--
Adam Kadlubek

Wide Range -- 17 speeds
 

On Mar 12, 5:26*am, The Dougster
wrote:

How peculiar. 17 speeds....

17 is a fine number!

Gauss's method enabling the construction of
a regular 17-gon was a landmark achievement
in mathematics.

There are insects with 17-year life cycles
(possibly because of the advantages of
it being a prime number of years); see
http://en.wikipedia.org/wiki/Magicicada

Tom Ace

Wide Range -- 17 speeds
 

On Mar 12, 12:09*pm, Phil W Lee phil(at)lee-family(dot)me(dot)uk
wrote:
The Dougster considered Thu, 12 Mar
2009 05:26:20 -0700 (PDT) the perfect time to write:





Hi!

I use:

24 / 35 / 51 x 11 / 13 / 16 / 19 / 24 / 28 / 34

chain rings and cogs on my Thunderbolt recumbent.

I've noticed that small/small and large/large combinations are
excluded by most designers due to rear derailer jockey cage overtravel
and chain misaliagnment and have confirmed the overtravel happens on
my bicycle, while the misalignment does not since this recumbent has a
long chain line.

I fitted a "low-normal" rear derailer....

Ruling out 2 of each extreme combination, from 3x7=21 choices I now
have a "17-speed" bike with around 650% range. How peculiar. 17
speeds....

My next project, since the cables are routed bare and parallel on the
long OSS (Over Seat Steering) column, is to make two small blocks of
metal with set screws and holes to actually "lock out" those
combinations. We'll see how that goes in a follow-up post here.

'Nuff said..

Doug Goncz
Replikon Research
Seven Corners, VA 22044-0394

I'd love to see how the mechanical lockout works - do post some
pictures somewhere when you've got it running.

Locking out bad combinations would be good, as it allows use of a
wider range than is sensible/safe with no lockout.
Given the risk associated with the ability to select gears which the
chainlength or tensioner cannot support, I'd think that few
manufacturers will ever recommend those super-wide ranges until
suitable lockouts are easily available.
Could this be one driving force behind electronic changing?
It would certainly make lockouts trivially easy compared to purely
mechanical methods.- Hide quoted text -

- Show quoted text -

Thanks for showing interest in the lockout, Phil.

All that is required is:

1) Low-Normal Rear Derailer (uncommon)
2) Low-Normal Front Derail (common)
3) Control cables parallel
4) Two blocks of metal, such that:

a) Both cables pass through each block
b) One cable is attached to each block
c) Block touch in the "next to worst" big/big and small/small
combinations you *can* use,
d) Setup is strong and stiff enough to prevent "forbidden"
combinations.

So c) on this bike is 24 / 15, which is 1st front, 3rd rear, and also
51 / 24, which is 3rd front, 5th rear, all through the magic of
assuming even steps of cable travel in the rear (I think this is
true), and assuming 2 front cable travel steps in front is equal to 4
cable travel steps in the rear (this may not be true).

If that last is not true, then I *think* four blocks, locking out big/
big and small/small separately, are needed. I have about four or five
inches of cable bare and parallel to play with, so we'll see.

A block to me would be about 3/4 inch long, 1/4 inch thick, and I
think the cable is 2 mm, so each block would have a pair of parallel
2mm holes in it, and set screw holes. There are ways to "peck drill"
such long, skinny holes without breaking the drill bit. Aluminum block
material, or *maybe* Delrin...

Hey, feel free to try it. Lots of mountain bikes have all four cables
bare and parallel on the top tube or another tube. "Not invented
here?" Peh. I'm not married to it!

Doug

Wide Range -- 17 speeds
 

On Mar 12, 1:42*pm, Tom Ace wrote:
On Mar 12, 5:26*am, The Dougster
wrote:

How peculiar. 17 speeds....

17 is a fine number!

Gauss's method enabling the construction of
a regular 17-gon was a landmark achievement
in mathematics.

There are insects with 17-year life cycles
(possibly because of the advantages of
it being a prime number of years); see
*http://en.wikipedia.org/wiki/Magicicada

Tom Ace

Well, I'm peculiar, and folks like me just fine, Tom! :) Meaning, I
said peculiar, meaning different, not "oh Dear, turn your head..."

Yeah, we've had a few cycles of 13-year swarms here in No. Va., USA.
Yikes! Attack of the Ubiquitous Chirping Bugs from Hell.

Doug