6-7-8 speed rear freewheel size & compatibility
09-24-09, 11:06 AM
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6-7-8 speed rear freewheel size & compatibility
So I'm looking at a lovely 8 speed Sachs freewheel for one of my Cannondale ST400's on which I'm installing a complete new drivetrain (105 triple FD, Truvativ triple crank, Ultegra long cage RD) and wondering if it's the same size when installed as the 6-speed Suntour that's already on there. Does the 8 speed freewheel just use thinner/more narrowly spaced cogs, or does it result in a wider rear spacing somehow. Not talking about a freehub (I know those are much wider), but a freewheel.
Also know I will need to go to an 8-speed shifter if I want to keep it indexed and am assuming that an 8 speed Shimano would be perfectly compatible- your comments on that are appreciated. IN the interst of full disclosure, I already have a 7 speed Sachs freewheel and Shimano indexed shifter on another bike.
Thanks!
Also know I will need to go to an 8-speed shifter if I want to keep it indexed and am assuming that an 8 speed Shimano would be perfectly compatible- your comments on that are appreciated. IN the interst of full disclosure, I already have a 7 speed Sachs freewheel and Shimano indexed shifter on another bike.
Thanks!
09-24-09, 11:27 AM
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The 8sp is wider than the 7sp., that's why 8sp FW's never took off. I have the diagrams of the Sachs FW's, and it clearly shows the 8sp being wider than the 7. The only 8sp. hubs I know of are Phil Wood currently.
The cogs for all 6,7and 8sp Sachs FW's were the same width. The spacing was cogs 1.8mm, spacing 3.2mm.
The cogs for all 6,7and 8sp Sachs FW's were the same width. The spacing was cogs 1.8mm, spacing 3.2mm.
09-24-09, 11:44 AM
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Aha. So I could go with a Sachs or Shimano 7 speed FW and retain the same rear stay spacing as with the 6 speed that's on there now?
09-24-09, 07:40 PM
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You can run the eight speed if you switch to a longer axle, and re-space and dish your wheel. I have that set up on three Mavic hubs, and also a Campy Record hub. Also I believe some of the Sachs index to Shimano, some Campy. I am running Campy eight speeds.
09-24-09, 07:50 PM
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Are you sure? The op says he has a freewheel. Mavic didn't make any freewheel rears did they?
09-24-09, 08:01 PM
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I own three of them, Paris Gao Dakar group , and two silver one which I do not know what group. https://www.firstflightbikes.com/1990_Salsa.htm
09-25-09, 05:51 AM
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Have you seen any axle bending with these 8-speeds? I thought older hubs designed in the 120/126 era did not fare well when extended to 130.
09-25-09, 06:01 AM
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Yes, the Sachs 8-speed FW w/brown spacers is Campy compatible. I don't know what the spacer color is for Shimano compatible. I'm running a Sachs 8-speed on a Campy Athena hub.
Generally a 7-speed FW will fit in place of a 6-speed without any changes. It is ~1mm wider, though, so if your frame/hub combo gave tight clearance with the 6, you may need to insert one or two 1mm spacers on the FW side of the axle.
