We do not handle that many children's bikes... we partner with another local charity that takes the ones that are donated and gives us vintage bicycles that they do not need for a child oriented program that donates 1000's of bicycles to needy children along with other sporting gear.
I used to volunteer for this other charity as well and the best part of the day was when you could roll out a bicycle for a child, or children who not otherwise afford one... seeing the joy in their eyes is like nothing else and many have been brought to tears, along with their parents.
Sometimes we have wee little bairns in our shop and it is really enjoyable to work with them as because we are a teaching shop, they get to get their hands dirty and learn all about their bicycles.
We also run a program for inner city you that are at risk, it has been very successful and the kids in the program get to keep the bikes they build which teaches skills, puts more value into the bike they have, and develops community between them and the volunteers that help.
I think that more than just being about bicycles, it is about that community and building a stronger one.