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#1
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Compact front derailleur on large diameter seat tube
I have a Scott CR1 frame that has a diameter 35mm seat tube. Per Campy specs
the derailleur braze on's mounting slot should be centered 27.2mm from the middle of the seat tube. It seems odd to me that Campy specs the mounting slot further away as the diameter of the seat tube get larger, e.i, (seat tube/mounting slot in mm) 28.6/24.75, 32/26 and 38/27.2. This means that the derailleur must have more inward travel as the seat tube gets larger in diameter, since the chainline doesn't change with the diameter of the seat tube. My problem is that with a Campy compact front derailleur adjusted to the maximum inward position will not clear the chain in the last 2 rear cogs. The chainline is correct. I don't see any fixes to using a compact crank on this frame other than: 1. Get a new derailleur that moves inward more. 2. Modify the derailleur, grind metal off, so it move more inward. 3. Make a custom brazeon that has the slot more inward by about 2mm. Anyone else run into this problem? |
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#2
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Use a standard front der...
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#3
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wrote in message news
I have a Scott CR1 frame that has a diameter 35mm seat tube. Per Campy specs the derailleur braze on's mounting slot should be centered 27.2mm from the middle of the seat tube. It seems odd to me that Campy specs the mounting slot further away as the diameter of the seat tube get larger, e.i, (seat tube/mounting slot in mm) 28.6/24.75, 32/26 and 38/27.2. This means that the derailleur must have more inward travel as the seat tube gets larger in diameter, since the chainline doesn't change with the diameter of the seat tube. My problem is that with a Campy compact front derailleur adjusted to the maximum inward position will not clear the chain in the last 2 rear cogs. The chainline is correct. I don't see any fixes to using a compact crank on this frame other than: 1. Get a new derailleur that moves inward more. 2. Modify the derailleur, grind metal off, so it move more inward. 3. Make a custom brazeon that has the slot more inward by about 2mm. Anyone else run into this problem? The IRD Compact front derailleur may work but you'd have to try it out. |
#4
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Yes thanks for the tip I have one on order from Excel. I hope it works out.
"Tom Kunich" wrote in message .net... wrote in message news I have a Scott CR1 frame that has a diameter 35mm seat tube. Per Campy specs the derailleur braze on's mounting slot should be centered 27.2mm from the middle of the seat tube. It seems odd to me that Campy specs the mounting slot further away as the diameter of the seat tube get larger, e.i, (seat tube/mounting slot in mm) 28.6/24.75, 32/26 and 38/27.2. This means that the derailleur must have more inward travel as the seat tube gets larger in diameter, since the chainline doesn't change with the diameter of the seat tube. My problem is that with a Campy compact front derailleur adjusted to the maximum inward position will not clear the chain in the last 2 rear cogs. The chainline is correct. I don't see any fixes to using a compact crank on this frame other than: 1. Get a new derailleur that moves inward more. 2. Modify the derailleur, grind metal off, so it move more inward. 3. Make a custom brazeon that has the slot more inward by about 2mm. Anyone else run into this problem? The IRD Compact front derailleur may work but you'd have to try it out. |
#5
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I got the IRD and it works!
wrote in message ... Yes thanks for the tip I have one on order from Excel. I hope it works out. "Tom Kunich" wrote in message .net... wrote in message news I have a Scott CR1 frame that has a diameter 35mm seat tube. Per Campy specs the derailleur braze on's mounting slot should be centered 27.2mm from the middle of the seat tube. It seems odd to me that Campy specs the mounting slot further away as the diameter of the seat tube get larger, e.i, (seat tube/mounting slot in mm) 28.6/24.75, 32/26 and 38/27.2. This means that the derailleur must have more inward travel as the seat tube gets larger in diameter, since the chainline doesn't change with the diameter of the seat tube. My problem is that with a Campy compact front derailleur adjusted to the maximum inward position will not clear the chain in the last 2 rear cogs. The chainline is correct. I don't see any fixes to using a compact crank on this frame other than: 1. Get a new derailleur that moves inward more. 2. Modify the derailleur, grind metal off, so it move more inward. 3. Make a custom brazeon that has the slot more inward by about 2mm. Anyone else run into this problem? The IRD Compact front derailleur may work but you'd have to try it out. |
#6
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I second thought the IRD didn't work after road testing. The derailleur
wouldn't mount low enough so the chain derailed when shifting to the big ring. Also the spring tension is too high and self shifted back toward the little ring. I finally bit the bullet and modified the Campy record derailleur by taking metal off a pivots point to increase travel and sanding down the inside of the cage for more clearance. wrote in message ... I got the IRD and it works! wrote in message ... Yes thanks for the tip I have one on order from Excel. I hope it works out. "Tom Kunich" wrote in message .net... wrote in message news I have a Scott CR1 frame that has a diameter 35mm seat tube. Per Campy specs the derailleur braze on's mounting slot should be centered 27.2mm from the middle of the seat tube. It seems odd to me that Campy specs the mounting slot further away as the diameter of the seat tube get larger, e.i, (seat tube/mounting slot in mm) 28.6/24.75, 32/26 and 38/27.2. This means that the derailleur must have more inward travel as the seat tube gets larger in diameter, since the chainline doesn't change with the diameter of the seat tube. My problem is that with a Campy compact front derailleur adjusted to the maximum inward position will not clear the chain in the last 2 rear cogs. The chainline is correct. I don't see any fixes to using a compact crank on this frame other than: 1. Get a new derailleur that moves inward more. 2. Modify the derailleur, grind metal off, so it move more inward. 3. Make a custom brazeon that has the slot more inward by about 2mm. Anyone else run into this problem? The IRD Compact front derailleur may work but you'd have to try it out. |
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