Frame size help for a smaller person

[ishaw]

My youngest son, 13 in October has recently got into mountain biking.

I built him up a very well equipped bike (slx 1x11, hope brakes, fox forks, e-thirteen cranks, Mavic cross trail wheels etc). He goes out riding quite a lot and there are some local trails he's getting good use from.

Today he told me his friends think I'm the coolest dad ever as I built him the bike they are all jealous of.

The riding he does includes jumps and he wants to get a full susser.

Being only 12, and not tall for his age, I stuck with a 26er. 15 inch frame c2t though it does have massive tyres, magic Mary iirc.

He wants a full susser, and keen on larger wheel size (29er is king according to YouTube in his eyes). Also wants a dropper.

Being small-ish, can a larger wheel size be suitable? If so , how does sizing compare to a 26er frame for example?

Id expect a larger wheel makes the frame larger, but a recent acquisition (transition patrol) insrge seems quite small (27.5er) in hand, not got wheels yet.

In short, should I be aiming for a small 27.5 or 29er and it will be comparable to the 26er equivalent or am I needing something even smaller?

I'd be looking to buy a used frame and swap parts probably, so don't want to get this wrong.

 

[CassidyAce]

If a 15" 26-er is a good fit, then a 15" 29-er should be fine too. At the risk of stating the completely obvious, regardless of wheel size, they're designed for the same length of leg; and because the proportions of people haven't changed much between the 26-er era and the 29-er era, the frames are designed for pretty much the same lengths of torsos and arms too. In other words, a small 29-er is designed for the same people that small 26-ers were. If you're mainly concerned about stand-over height though, you're best off looking at the sizing guides and exact geometry on the relevant brands' websites; details of previous years' models are often still available. After all, some things are even more important than wheel size.

 

[ishaw]

Hi, thanks for the reply, you got the gist of my dilemma. It's the stand over and reach that I was concerned about, I was thinking bigger wheels need a longer wheelbase so how that would compare and work for a smaller chap.

Obvious when you say look at geo charts, I can at least compare with the 26er which he's enjoying thrashing and fits nicely.

 

[novocaine]

If he's doing jumps down the park I'd have thought 26" would still be king. If he's heading out to the hills to ride down fast then a 29" would indeed win out. I'd say split the difference, but it looks like 650b is already dead in the water.

oh the trials and tribulations of being a dad. post what you wind up doing, I'm looking at the same conundrum for my young man.