Isis drive

Could someone please explain to me what the “isis” hub is and why unicyclists think they’re so great?


Industry standard for the specs of the splines on the hub and cranks. In theroy It would allow you to be able to put any ISIS cranks on any ISIS hub.

its a type of splined. I dont know why people think they are so great but I like mine. ISIS splineds have a bigger axle for the crank to fit onto, and they only have 10 splined, compared to like 36…

well thats what im pretty sure they are. :slight_smile:

Any splined interface–ISIS is just the most common in the cycling world–between the crank arms and the hub will result in a more solid interface between those two components. Splines make the hub look like it has teeth in it–like a gear (see picture below)–so it reduces the chance of the crank unexpectedly rotating on the hub.

A traditional hub has a square interface between crank and hub, and because there are fewer sides (just four; see picture below) that intersect, it’s more prone to being torqued and deformed.

That said, it’s really only in more extreme circumstances that the splined interface is a necessity–trials, street, and muni, mostly. Square taper hubs are generally fine for freestyle, road, distance, etc.

pkittle explained the difference between splined and traditional cotterless. The reason we favor the ISIS standard is because it’s a standard (assuming people adhere to it). Before unicycle makers started using ISIS, we had incompatible hubs & cranks for DM, Profile, KH, Qu-Ax and others. One or more of those may have fit each other; I’m not sure. Now you can buy a pair of cranks and have it fit more than one of your unicycles.