I am going considering several ideas about lowering the basic height of bike for my 13yr .
1. how much can i cut off seat cushion and still be ok .1/2 " to 1" ? Is there a preferred way to do this? do i cut across the length or just close to tank ?
2. shock adjustments? Man i will need some advice on that.
thanks guys for any advice you can offer
Suspension shops offer that kind of service but it is complicated because they place a spacer between the seal head and the top out plate. I would worry about it changing the geometry and overall handling. First I would find the proper springs for his weight, then shave off some foam and perhaps shorten the sub frame. You can safely remove up to 5mm from the subframe and reweld it back together. Even Ricky Carmichael has the subframe cut shorter.
I had my suspension lowered one inch internally, forks and shock, with no noticeable difference in handling. I recommend this method over any other lowering tricks. The best part is it's reversible if needed. Taking one inch out of the suspension gives about a additional two inches leg room. It also doesn't affect the way the suspension works. I'm really surprised that more people don't have it done to their bikes.
If you go the seat shaving route after using the electric knife use a angle grinder to smooth the rough edges. depending if you go as much as freestlyers do you will need to modify the seat cover by adding a little more material (vynl) at the front of the seat only about 1" on both sides. Try lowering the sub frame will gain a small amount of in seam hight also. This obviously is the cheaper route rather than the internal suspention mods.