Join Date: Dec 2007
Location: Shippensburg, PA
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No such thing as 9-speed vs. 10-speed chainrings. Just marketing hype...
Read Sheldon Brown's site on the subject.
The crown thickness of said rings is the same, I have been running 50-39-28 ("9-speed" Salsa granny wonderfully replaced the original FSA "10-speed" 30T granny) for about an year now.
The jump 39-26 in front in your case may require a "chain watcher" device, otherwise the chain might drop onto the BB shell at rapid downshifting in front.
Since we are talking real low mounting for the "chain watcher" here, due to lowered FD to fit your 48T, the only one which will fit (and it could be a VERY close call) is the N-Gear Jump Stop
Only 10 bucks and Nick is great to deal with.
You would have to fine-tune it to avoid the interference with the FD's inner plate, a 2-minute job.
The 3rd Eye "chain watcher" made by Deda won't fit since it would definitely interfere with the BB shell. Don't ask how I know...