Joined: Feb 2012
Posts: 19,364
Likes: 5,503
From: Rochester, NY
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
With the wider chains and cog to cog spacing that 7 speed systems have the chainline being spot on is a lesser need, than with the current 10+ systems. Still, aiming for the center is a good goal and the minor unavoidable tolerance will be OK.
Not mentioned is the chain drop that has motivated so much 1 by chainring tooth design and cage pivot clutches. Some will leave the ft der on the bike just to act as a guide and help prevent chain drop. Back in the day ring teeth had a higher peak, engaged the chain link deeper, than is current with rings designed to shift (as in a 2 by). So if you plan to just use one of the 2X rings and a rear der without a pivot clutch be aware that you could easily loose a chain at the wrong moment. Andy
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AndrewRStewart