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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 |
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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 |
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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 |
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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. |
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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. |
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Wide Range -- 17 speeds
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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 |
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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 |
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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 |
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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 |
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