Retro vs modern sizing, and teen bikes

Firstly, apologies if this is covered elsewhere or there is a sticky covering it. I could equally have posted in MTB wanted!

I am after a bike for my son (daughter as well possibly). I am in the odd situation of having wife and three children all exactly the same height right now of between 5 ft and 5' 1". My wife and I both ride - a mix of road and XC. She on a 15inch specialized myka hardtail (triggers broom...).

We have previously bought Islabikes for them, no suspension and pretty light weight. But they are now getting to the size of adult bikes.

I made the mistake of a hasty purchase of a halfrauds special used off an auction site in lockdown - the trouble it is simply too big and heavy. in hindsight the wrong thing to buy.

So now I am thinking of something like an older non-suspension mtb or a small hybrid - like a 90's specialized hardrock or the like? it is going to be lighter and easier to ride, and perfectly fine for the mix of road and bridleway we might do round here.

What advice do yo have on a good thing to look for?

I'm not sure on sizing either.

Finding a 15 inch older specialized hardrock is proving much harder than larger sizes! I'm assuming that is the right size to look for based on the sizing of the newer specialized. Am I looking for a 15 inch older frame? would I get away with a 17? Finding sizing information for older stuff seems really hard!

thanks in advance.

Re:

17 would be too big for someone 5.1.

I’ve just sold a cheap 14.5 backwoods and it sold quickly to someone with same story. Needing bike for kids but Halfords stuff is crap etc.

Thanks.

So I am looking for something like 14 or 15 inch size then...

and am I right in thinking the backwoods you sold, or a late 90s specialized rockhopper would be bang on? I look at the islabikes then look at them and see lots of similarity!

bad mtb and I am looking at 14-15kg. which is about 4-5kg too heavy. if I can get a bike down to 10-11kg I might actually get some hills out of them...

Re:

Yeh something that sort of size.

Older bikes tend to be lighter if they of decent spec. I bet you can pick something decent up for sub 150£

If you mention your location maybe a local member has something for you

location... (face palm) of course.

in Herts, St.Albans, just north of London near the M1.

Lovely looking 15 inch rockhopper went on that auction site today. very clean. Its the sort of thing I need to pick up I think. Must have patience!

Left field, but a Brompton or similar rugged folder might do the job if the bridleways aren't too rough (although I've taken mine down some pretty rough stuff). Missus is 5 ft 2 and likes the low step over on mine. Plus they have fantastic re-sale value/room to grow.

Maybe look for one of the larger Isla bikes?
They do adult and "tween" size bikes as well.....

Re:

you can join the long list of people with 14" Kona frames, ctt, which seem to work, my Mrs and daughter both 5ft ish but daughter has longer legs and fits a 14" Orange Prestige that is too big for the Mrs (standover height being issue). Mrs also has a more modern 14" Trek, and the daughter a new Frog 73 that is also good.

Re:

I went the way of a Kona for my 11 year old that had out grown the Isla Beinn 26s - we're in Harpenden so you might see us around!

There's some good advice here thanks all.

That Kona next to the islabike tells a story - looks like slightly longer reach and standover height on the Kona. either that or a perspective artifact! Wife and I get out into Heartwood and Symondshyde regularly. IfI want longer I tend to go out towards the Ayots.

I have no knowledge of Kona at all.
I can see for sale right now a few examples sort of near me
Two Kona hahanna
https://www.ebay.co.uk/itm/Kona-Hahanna ... SwIVNfChJD
https://www.ebay.co.uk/itm/Kona-Hahanna ... SwtjdfL6n5


and one Kona explosif -
https://www.ebay.co.uk/itm/Kona-Explosi ... SwOOFfMSKO

Looks like the three above are steel frame.


and a kona caldera bare frame:
https://www.ebay.co.uk/itm/Kona-Caldera ... Sw8WZfLFIJ
(edit. damn and the kona gone!) someone on here?

and a trek down in guildford that looks interesting
https://www.ebay.co.uk/itm/Treck-Single ... 3682687721

or a specialized again down in Surrey
https://www.ebay.co.uk/itm/SPECIALIZED- ... 3671686626

I think perhaps on the right track with those examples?

Interesting comment on the choice of a brompton - if I did manage to get one of those in the house it would get "requisitioned" by my wife straight away for the commute!