A hyperthetical plan at the moment but would this work and is it worth it in terms of ride and weight?

Getting my son a second hand 24″ bike and so assuming it has a 1 1/8 headset thought I’d try and pick up some bargain second hand air forks eg fox rl80 and take out the rst/suntour things that come on them.

That would mean swapping rim brake but I have a spare disk front brake in the parts bin currently.

So would that just leave the need for a new wheel that is disk compatible wouldn’t it.

Have I missed anything? Hoping to do it without spending much. Are there other fork options that would be worth a look?

Air Tora, put one on my boy’s Kona Shred 24.
Has spacers to adjust travel from 80 to 120mm, and the big benefit I guess you’ve already thought of is the ability to set pressure for his weight as he grows.
It’s done him fine from XC rides around Delamere to full on DH in Leogang.

Front brake, disc wheel and a fork. If you were looking to really save, get some old marzocchi air forks with v brake stubs and then you wont need a new wheel.

Got a shred 24 as well, rebas and discs for my lad. Decent bike. The Voltage 24 is a good option as well.

Cheers for that.
What model marz should I be looking for?

Done this recently , put a pair of SIDS on my sons Carrera Blast together with CRC Deore hydraulics.
He really is having a Blast now !!

got an 06 Marzo Z1 SL on my eldest’s Stinky 2-4. You can adjust the negative air to drop the travel, just the job

I went through the whole decent fork for a 24 wheel bike with my lads a few years back. Problem is the v break bosses on most forks are fixed and suit 26″ wheel therefore are not compatible with a 24″ bike.

Some of the old carbon Pace forks had the rim brake bosses clamped on and could be slackened off and slid down the fork leg to suite a 24″ wheel. It worked fine with my sons Scott Nitreous 24.

Picture here: http://www.flickr.com/photos/seb1000/5812658833/in/set-72157626917788880

not trying to put the OP off but as griffiths1000 has said fitting v brakes may be difficult as the fork will no doubt be a 26″ and the wheels would be 24″ so the brakes will never line up to work on the rim…the way around this would be to run a 26″ front wheel but with a 24″ on the back it would most likely mess up the geometry and handling of the bike…
having said that running 24″ rims with a 26″ fork wont be too much of an issue…like you said your only option would be to run a disc on the front…but you’ll need a disc hub built onto the 24″ rim which may increase your cost unless you find a cheap one already built on ebay…but be mindful of the fact that a lot of these will be burly jump wheels…

just remembered i have an atomlab trailpimp front hub for sale if you want..its 32 hole and is disc ready….can be used with a qr or the bolts that come with the hub…i upgraded to 20mm 6 months after i bought the wheelset and havent used it since….the hub is about 8 years old but the bearings are in perfect working order and the hub is like new

I put a set of 02 Marz MX4 on a Kona Shred 2-4 for my other boy. It already had disc wheels so not a problem. The Kona’s are quite high at the front end anyway so the Marz fork didn’t change the geometry from the original cheap & nasty one that was fitted.

I would recomend the shred 2-4 if you don’t alredy have a bike for him. They aren’t the lightest but as colp said they will handle anything from xc to DH. It has been through all three of my kids, ridded hard and still going strong.