Having watch her ride her bike this weekend, I've concluded that LittleKnees will be too big for her current bike after what seems like the annual summer growth spurt. I hadn't realised kids bikes are generally sized by the wheels - perhaps it wasn't that way when I was a kid? - anyway, she currently has a 20" wheel bike, and as I understand it the next step up is a 24" wheel bike. She's quite taken with one in Decathlon with mudguards. However, it weighs 14.9kg according to Decathlon, which is a preposterous amount for her to haul about. Her current bike weighs about 13kg I think - it's about the same as my utility bike anyway, so it's no surprise she gets tired going uphill. Last year I built up a bike for me by buying a frame and then picking up bits here there and everywhere. She was fascinated by the project, and I wondered if I could replicate it to make her next bike, and perhaps get her a lighter bike, for less money, and in the process she could learn a bit about how bikes fit together, which she seems interested in. My thought process was to buy an older 'quality' frame (probably a 'ladies' one as she likes the low cross bar on her current bike) and work from there - as long as it takes decent width tyres and mudguards it will do I guess - I was thinking a late 80s / early 90s 'womens' rigid MTB would be ideal if they are small enough - so we finally get to the question - would a very small 26" MTB frame be ok for someone about 135cm (4ft 6-ish) or would I need to find a 24" version do you reckon? Cheers.