Solo DS Narrow-Wide Chainring

Shimano's direct mount cranksets: M9100, M8100, M7100 and M6100. The ring attaches straight to the crank arm rather than to a spider, so there is no bolt circle to measure — either your crank takes a Shimano direct mount ring or it does not. SRAM's three-bolt direct mount is a different shape and needs the Solo DX, while SRAM's T-Type cranks — the ones that come with an Eagle Transmission groupset — take neither, because they use their own eight-bolt interface. Cranks with a four-bolt spider need the Solo or Solo 96.

28T, 30T, 32T and 34T. The choice is gearing rather than fit — every size uses the same direct mount interface, so nothing about the installation changes with size. 32T is the usual trail choice on a wide-range cassette, 28T and 30T make steep climbing easier, and 34T suits flatter ground or a faster pace.

The teeth and the mounting interface are machined from a single piece of 7075 rather than a ring bolted to a separate carrier. That removes the bolted joint, which is the part that flexes under load and works loose over time, and it lets the whole thing be lighter for the same strength. It also means there are no chainring bolts to re-torque — just the lockring that holds the ring to the crank.

Usually not. The alternating narrow and wide teeth fill the chain's inner and outer links so it grips the ring rather than bouncing off it, and with a clutch derailleur most trail riders never drop a chain. Downhill, bike park and racing are where a guide still earns its place, because there a single dropped chain ends the run — the Zippa Lite ISCG05 adds that for 30g if your frame has the tabs.

Only if it uses the same direct mount interface. This ring is made for the M9100, M8100, M7100 and M6100 generation; earlier Shimano cranks carried the chainring on a four-bolt spider, and those take the Solo 96 if the bolts are unevenly spaced, or the Solo if they sit evenly on a 104mm circle. Check what your current ring attaches to before ordering — that is the whole decision.