You’d think this would be a simple story…Wolf Tooth makes narrow-wide chainrings and now they work with SRAM’s T-Type Transmission groups. And it is, but it isn’t.
The Wolf Tooth Drop-Stop B chainrings were introduced when SRAM introduced their road Flat Top chains. The tooth profile changed slightly, making the wide teeth slightly less wide so they fit in between the outer chain plates better with less rubbing.
They also increased the roller pocket diameter for the Flat Top MTB chains, because those chains have slightly larger diameter rollers. This lets the chain fully drop in between the teeth, and keeps the roller resting on the load-bearing portion of the tooth rather than bottom out and not fully engaging.
Now, they’re adding mountain bike-sized Drop-Stop B chainrings with the SRAM 8-bolt direct mount pattern, which will have the proper 3mm and 0mm offsets…
Which chainring offset do you need?
SRAM’s DUB WIDE spindles are what come with the new Transmission groups, which use a 3mm offset chainring to achieve a 55mm offset. For most riders, that means you’ll buy the 3mm offset chainring to match things up. But just in case you’re using a different crankset, use the chart above to check what you need…because there’s a narrower 52mm chainline XX SL spindle for racers that would use a 0mm offset to achieve the desired 55mm chainline.
Confused yet? It’s not Wolf Tooth’s fault, it’s the way the bike industry has named the standard. The chain LINE offset is measured from the center line of the bike out to the chain line. The chain RING offset is actually a negative offset, bringing the chain line back in closer to the center line of the bike.
What about other cranks?
These new “B” chainrings are backward compatible and will eventually replace the Drop-Stop A versions, so you can just order Drop-Stop B chainrings for any 9, 10, 11, or 12-speed chain. The chainrings are machined from 7075-T6 aluminum and come with eight stainless steel bolts. Weights from 65g to 77g, prices from $79.95 to 84.95, available in 30/32/34/36 tooth counts.
They’re also working on 104BCD and Race Face CINCH versions of the Drop-Stop B chainrings with the proper offsets and tooth counts for mountain bikes, so you’ll be able to run other cranksets with a SRAM Transmission group, including the original SRAM 3-bolt direct-mount cranks.