Direct Mount Chainrings for SRAM 3-bolt Cranks
SDM28-BST-B
Pairs well with
Direct Mount Chainrings for SRAM 3-bolt Cranks
Wolf Tooth is committed to provide the most precision components possible and has three different tooth profiles for optimal performance based on your chain type.
| Tooth Profile | |||
|---|---|---|---|
Tooth Profile |
Drop-Stop® B |
Drop-Stop® A |
Drop-Stop® ST |
| Chain Compatibility | |||
Chain Compatibility |
All 9s, 10s, and 11s Chains 12s Chains:
Not compatible with 12s Shimano HG+, 12s KMC, or 13s Campagnolo chains |
All 9s, 10s, and 11s Chains 12s Chains:
You can use Drop-Stop B when Drop-Stop A is not available* Not compatible with 12s SRAM Transmission (T-Type) and Road Flattop, 12s Shimano HG+, 12s KMC, 12s Campagnolo, or 13s Campagnolo chains |
12s Chains:
Not compatible with all other chains |
| Details | |||
Details |
 Tooth shape is nearly identical to Drop-Stop A, but has narrower teeth. Valley between teeth is deeper to accommodate larger rollers on Flattop chain. Outside faces of narrow and wide teeth touch chain to guide alignment. Drop-Stop B Chainrings |
 The original Drop-Stop tooth profile. The wide teeth are wider than Drop-Stop B. Outside faces of narrow and wide teeth guide chain alignment. Drop-Stop A Chainrings |
 Narrower teeth than Drop-Stop A. Wide teeth use Symmetric Trapezoidal (ST) profile to match extended inner edge on chain to create alignment (outside faces of wide teeth do not touch). Interaction of narrow teeth and chain are similar to Drop-Stop A and B. Drop-Stop ST Chainrings |
*We are in the process of migrating most Drop-Stop A to Drop-Stop B to make them compatible with SRAM Road and Transmission (T-type) Flattop chains.
The direct mount chainrings for SRAM cranksets replace your existing spider and chainring with one clean looking, lightweight, and stiff piece of machined billet. They are available in 3 different offsets: 6mm offset for 49mm chainline, 3mm offset for 52mm chainline, and 0mm offset for 55mm chainline and SRAM Transmission optimization. They are available in various tooth profiles to suit your drivetrain, including Drop-Stop B, which is optimized for SRAM T-Type Transmission and compatible with many other chains. Crankset and chainring compatibility questions? Check out our helpful guide here.
Compatibility
- These direct mount chainrings will replace your existing chainring and spider or replace the direct mount ring on SRAM cranksets including the DUB cranks. The ring is attached via 3 bolts on the back side of the spider near the spindle. Note that these chainrings are NOT compatible with SRAM 8-bolt direct mount cranksets.
- Also compatible with Cane Creek eeWings cranksets
- Wolf Tooth’s patented Drop-Stop® wide/narrow tooth profile for the ultimate chain retention and mud shedding ability
- There are 3 offsets:
- Boost: 0mm offset for 55mm chainline required for SRAM Transmission
- Boost: 3mm offset for 52mm chainline or Transmission compatibility with Super Boost bikes
- BB30: 0mm offset for BB30 short spindle cranks for 49mm chainline
- Standard MTB: 6mm offset for non-Boost mountain bikes, GXP and long spindle BB30 cranks for 49mm chainline
- Fat bikes: If your fat bike has a 170/177 rear hub spacing, use the standard 6mm offset
- Praxis Works Road/CX cranks use the 6mm offset. Praxis Works mountain cranks use the 3mm offset for their DM-A and 0mm offset for their DM-B chainrings.
- If you have a BB30 crankset (30mm diameter aluminum spindle) this measurement will determine whether it is a long or short spindle:
- If using a 9-speed drivetrain use a 10-speed chain (shifts and works well on a 9-speed drivetrain and fits the ring tighter for better chain retention).
Recommendations
- Recommend the use of a clutch style rear derailleur for the best chain security.
- An L-wrench works best since the crank spindle may contact a socket adapter and prevent it from engaging properly.
- Use the same 3 bolts to attach the Wolf Tooth ring or we carry replacement bolts
Related Products
- For a longer lasting and more durable option check out the CAMO System that offers stainless steel chainrings.
- We recommend using a T25 L-Wrench or similar for removal and installation of the bolts.
- The stock bolts are easily damaged when removing them to install a direct mount chainring. We have replacement bolts if you need them.
Tech Specs
Material: 7075-T6 aluminum
Made in the USA
WARNING Handling this product will expose you to chemicals, including lead, known to the State of California to cause cancer and birth defects or other reproductive harm. Wash hands after handling. For further information go to www.P65Warnings.ca.gov.
Tooth Profiles
Drop-Stop® B |
Drop-Stop® A |
Drop-Stop® ST |
|---|---|---|
All 9s, 10s, and 11s Chains 12s Chains:
Not compatible with 12s Shimano HG+, 12s KMC, or 13s Campagnolo chains |
All 9s, 10s, and 11s Chains 12s Chains:
You can use Drop-Stop B when Drop-Stop A is not available* Not compatible with 12s SRAM Transmission (T-Type) and Road Flattop, 12s Shimano HG+, 12s KMC, or 13s Campagnolo chains |
12s Chains:
Not compatible with all other chains |