We get lots of questions about why Wolf Tooth’s Drop-Stop (TM) chainrings are so much better at preventing chain drops than conventional single speed or shifting front chainrings. The answer is that chainrings with alternating wide and narrow teeth are much better at guiding a bouncing chain to mesh with the teeth as it falls into position.
The picture below shows a conventional single speed front chainring with the chain intentionally pushed off center to simulate a position a bouncing chain might temporarily be in while riding on rough terrain. The tooth on the right that is engaged with the narrow link of the chain does a good job centering the chain so the next tooth will fit between the wide link of the chain. The next tooth over allows the chain to move a lot off of center before it contacts the chain plate. Because it is so far off center there is a good chance that the next narrow chain link won’t mesh with the tooth which causes the chain to fall off the chainring.
The next picture below shows the same scenario but with a Drop-Stop chainring instead of a conventional single speed chainring. Just like before, the tooth on the right that is engaged with the narrow link of the chain does a good job centering the chain so the next tooth will fit between the wide link of the chain. But now the next tooth is wide so it does just as good of job aligning the wide link of the chain to the chainring as the narrow tooth did aligning the narrow link of the chain to the chainring. This improved alignment is enough to ensure the next tooth meshes with the chain and prevents it from falling off. It is important to point out that not all wide narrow chainrings on the market are created equal. Our extensive testing and engineering has led to our Drop-Stop (TM) design that assures the ultimate chain retention!
Want additional chain security?
Drop-Stop chainrings do a great job preventing chain drops but for added security we highly recommend using a rear derailleur with a clutch. The clutch resists derailleur movement and greatly reduces how much your chain bounces around when riding on rough terrain. Less chain bounce = less opportunity for the chain to pop off the chainring teeth. Plus they have the added benefits of virtually eliminating the annoying sound of the chain slapping against your frame and reducing mud induced chain suck. Both SRAM and Shimano offer 10 and 11 speed rear derailleurs with a clutch. SRAM labels the clutched version of their derailleurs “Type 2”. Shimano calls theirs “Shadow Plus”.
Seeing is believing
The detailed description above explains the science behind how Drop-Stop chainrings prevent dropped chains. But the best way to convince yourself that it really works is to see it in action. This Italian E-magazine has some great video of Drop-Stop vs. conventional front chainrings being put to the test on the trail.