Wide range 1x drivetrains found on modern mountain bikes are pushing the capabilities of what can be achieved using current chains and chainring designs, and thus different manufacturers have begun to incorporate a variety of proprietary features into their chains, chainrings and sprockets. e*thirteen Helix Cassettes are designed to bridge these differences and provide great shifting performance regardless of the chain, derailleur, and chainring in a given setup.
Regarding backpedal, our goal is to get at minimum a full backward-rotation of the cranks without the chain derailing. Still, since we are also prioritizing cross-compatible shifting, there are locations where features that are necessary to produce great shifts with one brand of chain may actually hurt backpedal with another brand of chain.. so we do our best to find a compromise that will work!
Since we can't test every setup and every combination of parts and frames, we have done our best to ensure great backpedal performance in the 3 largest sprockets of the cassette using the most common chains, namely SRAM, Shimano and KMC. In spite of this, any given setup may not have perfect performance in every sprocket.
As you might imagine, many variables therefore effect chain retention on cassettes while backpedaling - chainline, chainring size, chain flex and wear, frame alignment, and the individual component tolerances (variations from manufacturing) can all impact likelihood that your chain derails during backpedaling.
In real-world on-trail use, you would generally never need to backpedal more than 1/2 to 3/4 of a pedal stroke during a sudden backpedal for ground clearance reasons on a technical climb. Because of this, most riders discover this "issue" not while riding, but when the bike is on the stand or when lubing their chain.
Another thing to remember is that backpedal performance almost always improves over time, so even if you're experiencing a backpedal derailment with your new setup on the stand, it may very well solve itself after the chain has a chance to wear into the cassette over the first few rides.
Here are a few steps to take to optimize backpedal performance:
- Verify you are running the correct chainring offset designed for the chainline intended to be used on your frame.
- Verify your derailleur is adjusted correctly, particularly the B-Tension adjustment.
- Some BB/crank/chainrings have options for adjusting chainline. If your setup offers the option to move the chainline inboard, making this adjustment can improve the chainline in the larger gears. However, this makes the chainline worse in smaller gears and could impact backpedal performance in some of the smaller cogs.