My younger son's new 12.5 arrived last week and I've already been busy with tweaks:
- replaced the standard fat grips with Renthals trials grips, using Renthals grip glue (and a compressor to remove originals)
- replaced both brake cables with Teflon coated ones - much smoother
- removed rear brake second spring
- changed the spring position on front v-brake to softest return
- retorqued the swingarm bolts - as noted elsewhere, you could remove the shock and the swingarm still wouldn't budge!
- ordered several sets of replacement springs for forks from springmasters in the uk to see what works best. Standard springs are way too stiff. Will repost once I've found best setup for my three-year-old.
I think the grip and brake changes are essential fir younger riders with small hands.