You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
I want to build up two complete bikes for my 10 year old nieces - Ideally disc compatible (hate adjusting rim brakes) - As the overall build cost is for the two bikes value is a priority. Not necessarily the cheapest but a good deal - Anybody else built up some decent custom kids bikes? What frameset did you go for ? I'm thinking 24 inch wheels and maybe a longer frame as they're quite tall .. As per title rigid only .. Haven't started looking yet so ideas greatly appreciated- Enjoy your bank holidays : )
If they're big enough you could consider a 26" frame. My 11 yo uses a small 26" frame.
I built up a 13 inch Specialized Hardrock (used, off eBay) for my eldest. He was 8 at the time and I used 24” wheels. He’s 11 now, on 26” wheels. And he’s almost outgrown it.
Great little frame - will use it for my littlest when he outgrows his current bike.

Do you mean buying a cheap bike and upgrading the components? If not I'm not sure you can buy any frames that small. My son has an Orbea mx24 with rigid forks, I can recommend that if that's the route you're after.
Any excuse:

My eldest's cooker 24, built mostly with spares bin kit, the frame and fork cost me £50 from fleabay...
Before I spotted it I was eying up specialized hotrocks (she had a 20" hotrock before) and carrera blast/Luna's, Hoys basically anything you can think of...
If you want cheapish and can budge on the disc requirement I reckon the carrera saruna is an often overlooked option for a kids hybrid type bike (comes in 24 and 26 flavours). That assumes you're more after a pair of decent 'isla like' rigid bikes rather than full blown MTBs...
I think I've neglected looking at small 26er frames - thanks for mentioning - As im building the two bikes I'd like the same frames thus second hand Ebay options could be limited.. Didn't realise there was so little choice out there - Everything is complete bikes for kids with horrible components . .