Originally Posted by Chandne

Yes, running does but mostly leg bones. I am not looking to optimize solely for cycling...too old and slow for that. In addition to becoming a stronger cyclist though, I'm looking to gain bone density in my upper body too...arms, shoulder, collar bones, etc. Not doing it to look good from a vanity standpoint though I do look more balanced and feel much stronger when doing everyday things. I keep reading that lifting heavy weights (I go heavy for me, once a week) actually bends the bones a minuscule amount and that is what causes them to gain density. Running does the same thing but the "weight" comes from landing and putting pressure that cause the bones to deform or bend slightly. I'll take up swimming this Autumn.