While I can appreciate concerns of long term damage to growing limbs, I must admit that my son has been using spd’s for racing cross, xc,and road since around 9 or 10. If carefully set up, and bearing in mind the limited time actually wearing them, I thought it was worth the risk as the performance benefit is noticeable. All based on totally non-scientific assumptions of course! He also rides bmx, fixie, and general riding in flatties as they’re cool, to redress the balance.
His first pair of race spd’s were ladies, but the Sidi logo more than compensated for this slight indesretion.
Might have a rummage in the roof tonight and pop them in the classifieds.