Old 02-04-18, 01:37 PM
Join Date: Apr 2010
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Originally Posted by twocicle View Post
If you had tried the above, a big problem would have been with that choice of 50t "big" ring. Narrow-wide 1x chainrings are not intended to allow a chain to derail (ie: shift) and so do not have ramps, pins, ramping or tooth profiling to assist with chainring shifting. With the 1x chainring, this setup would simply not shift reliably to/from the big ring.

Solution is simple, just get a matched set of regular 50/34 compact crank 110bcd chainrings, then slap the 34t timing ring on the outside.

You would obviously need to add significant spacers to provide a gap to the timing ring, sufficient enough to prevent chain to chain contact when shifting up to the big ring (chains frequently ride on top of the big ring and a bit to the outside and so can tangle with a SSD timing chain).
Actually that's the point. It's intentionally a 1x drivetrain to go with an Eagle cassette. The chain line of the front/captain crankset matches up within a mm of the inner chainring of the rear/stoker crankset (in other words it is a better match than the outer chainring approach you mention), and the 50t narrow wide chainring lines up perfectly with the chainline of SRAM Eagle. It would be the lightest tandem drivetrain without sacrificing any gear range and it would be pretty cheap. Some of the shifts would be a few percent larger than what I am currently using but I don't think it would make an issue.

willhs is offline