My Dad is several states away, getting three months of intensive multiple myleoma related chemo, t-cell harvesting, etc. Assuming the treatment doesn't kill him (it happens), how safe is it for him to get back on a bike? So far, his bone density is normal (apparently taking core samples is not real pleasant). I don't know how long it takes for this disease to progress to the point where bones are snapping like twigs, but apparently it doesn't really kill anyone anymore (hopefully). He's 66, 220, and up to this point, tough as hell. Too inflexible to get on a tall bike without falling over, and not as interested in going that fast or trying to jump stuff anymore, so he'll probably get a relatively small dual sport and just ride around fields and the occasional trail. Low risk, but he doesn't react real quick anymore, so he still crashes with some regularity.