bluegoose
10-20-2005, 03:40 PM
I just ran across this line on Road Bike Riders weekly newsletter. It looks interesting. I'm curious to see if it will work equally well with a double or triple.
I cut and pasted from my email newsletter. There may be more info on roadbikerider.com.
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SRAM's New 'DoubleTap' Shifting System
Japan's Shimano and Italy's Campagnolo have owned the road component market for the last quarter century. Now Chicago-based SRAM, the respected maker of MTB equipment, has revealed how it intends to challenge the Big Two.
We've reported that SRAM's 2007 high-end road groups are in the works, and noted the secrecy surrounding its version of brake/shift levers. Photos of them (taken with the levers under glass) seemed to show just one shift lever behind a non-pivoting brake lever, similar to Campy's Ergopower design for rear downshifts but without a thumb button for upshifts.
How could SRAM's single shift lever allow gear changes in each direction? The secret was revealed last week and it's simple: If you push the shift lever slightly inward (toward the front wheel), you get a one-gear upshift (to the next smaller/harder cog). If you push the lever past the upshift point, you get a downshift to one, two or three larger/easier cogs.
SRAM calls this shifting method "DoubleTap." It's accomplished with a unique internal design dubbed "LeapFrog." It works with cams and sprockets that move over each other to shift either up or down the cassette. It simply depends on the amount the lever is pushed.
Here's another exclusive feature: SRAM's shift lever can be pulled back toward the handlebar like Campy's can, but with a benefit. When your hands are in the hooks, you can pull the lever to the bar and hold it there. In this position, all it takes is a slight hand rotation to hit the next higher gear. Sprinters should love this (if it works).
Other highlights:
---Front shifts work similarly. A light push on the lever drops the chain to the small chainring. Pushing farther shifts to the large ring.
---All gear and brake cables are concealed under handlebar tape, ala Campy, for a clean front end.
---The overall design of the brake/shift levers leaves SRAM looking similar to Campy or Shimano.
But SRAM claims to have thoroughly researched the shape, size and materials in order to make the levers more ergonomically perfect.
---According to the tech experts at cyclingnews.com, it appears that SRAM has adapted the 1:1 cable pull ratio of its off-road system. This ratio requires roughly twice as much cable movement to initiate a shift compared to Shimano STI or Campy Ergopower. This does not affect the amount of lever movement required to initiate a gear change, thanks to the internal design. But it should mean that the SRAM system is more tolerant of slight misalignments and cable/housing friction. It also means that DoubleTap brake/shift levers won't work with Campy or Shimano rear derailleurs.
---It's expected that SRAM's DoubleTap technology will be available in two 2007 groups due to reach the market sometime in '06. One group with lots of carbon is at the level of Record and Dura-Ace. The other, primarily alloy, will compete with Chorus and Ultegra. SRAM will include brakes, derailleurs, a crankset, 10-speed cassette and chain. These parts appear to be pretty standard. It's the DoubleTap shifting that sets SRAM apart.
If you want to see the shifters and how they move, we have photos from SRAM (with a reprint of this report) at http://www.roadbikerider.com/sram.htm
I cut and pasted from my email newsletter. There may be more info on roadbikerider.com.
---------------------------------------------------------------------------------
SRAM's New 'DoubleTap' Shifting System
Japan's Shimano and Italy's Campagnolo have owned the road component market for the last quarter century. Now Chicago-based SRAM, the respected maker of MTB equipment, has revealed how it intends to challenge the Big Two.
We've reported that SRAM's 2007 high-end road groups are in the works, and noted the secrecy surrounding its version of brake/shift levers. Photos of them (taken with the levers under glass) seemed to show just one shift lever behind a non-pivoting brake lever, similar to Campy's Ergopower design for rear downshifts but without a thumb button for upshifts.
How could SRAM's single shift lever allow gear changes in each direction? The secret was revealed last week and it's simple: If you push the shift lever slightly inward (toward the front wheel), you get a one-gear upshift (to the next smaller/harder cog). If you push the lever past the upshift point, you get a downshift to one, two or three larger/easier cogs.
SRAM calls this shifting method "DoubleTap." It's accomplished with a unique internal design dubbed "LeapFrog." It works with cams and sprockets that move over each other to shift either up or down the cassette. It simply depends on the amount the lever is pushed.
Here's another exclusive feature: SRAM's shift lever can be pulled back toward the handlebar like Campy's can, but with a benefit. When your hands are in the hooks, you can pull the lever to the bar and hold it there. In this position, all it takes is a slight hand rotation to hit the next higher gear. Sprinters should love this (if it works).
Other highlights:
---Front shifts work similarly. A light push on the lever drops the chain to the small chainring. Pushing farther shifts to the large ring.
---All gear and brake cables are concealed under handlebar tape, ala Campy, for a clean front end.
---The overall design of the brake/shift levers leaves SRAM looking similar to Campy or Shimano.
But SRAM claims to have thoroughly researched the shape, size and materials in order to make the levers more ergonomically perfect.
---According to the tech experts at cyclingnews.com, it appears that SRAM has adapted the 1:1 cable pull ratio of its off-road system. This ratio requires roughly twice as much cable movement to initiate a shift compared to Shimano STI or Campy Ergopower. This does not affect the amount of lever movement required to initiate a gear change, thanks to the internal design. But it should mean that the SRAM system is more tolerant of slight misalignments and cable/housing friction. It also means that DoubleTap brake/shift levers won't work with Campy or Shimano rear derailleurs.
---It's expected that SRAM's DoubleTap technology will be available in two 2007 groups due to reach the market sometime in '06. One group with lots of carbon is at the level of Record and Dura-Ace. The other, primarily alloy, will compete with Chorus and Ultegra. SRAM will include brakes, derailleurs, a crankset, 10-speed cassette and chain. These parts appear to be pretty standard. It's the DoubleTap shifting that sets SRAM apart.
If you want to see the shifters and how they move, we have photos from SRAM (with a reprint of this report) at http://www.roadbikerider.com/sram.htm