i know theyre stronger, but what makes them so strong. whats the difference other than a different shape to slide the cranks onto
different materials, different designs, more materials, etc…
The splines create a larger surface for the hub and cranks to touch. Same force, more area, equals less pressure. The axle of a splined hub is stronger because of they are made from stonger materials. This is because there is no reason of having a good quality and strong bond between the axle and the cranks if the axle is weak.
standard hubs (which are square-tapered) :
imagine the axle having a [ ] shape, and the crank having the same [ ] shape to fit over it, and then the crank is held in place over the axle with a 14mm bolt.
the splined hubs:
imagine the axle having almost a * shape, and the crank having the same * shape to fit over it. there is a lot more surface area, more area to spread the load, on a * than on a [ ].
unicycles require stronger hubs and rims than a bike normally does, because instead of spreading the weight between two wheels, it is all forced down on one.
I thought it had a little more to do with having a larger diameter axle. If you put splines on it then you can take advantage of almost the entire width of the axle, and thus have a larger diameter chunk of metal (which is harder to break).
The splines also, as you said, increase the contact surface between the crank and hub. But I would guess that that is more to prevent the interface from wearing out as quickly.
That’s What I think, anyway. Someone else will come along shortly and correct me.
i understand, its all making sense now, thanks