Hello everyone! I’m 5’1″ tall and I’m confused about the mountain bike sizes. Which size should I pick – 14″ frame MTB or kid’s 26″ wheel bike? Need your suggestions. Thanks!

According to the size guide for Santa Cruz bikes, you’re on the borderline between their XS and Small sizes, so not on a kid’s bike yet. What kind d of bike/budget had you in mind?

https://www.santacruzbicycles.com/en-GB/bikes/5010

My 150cm daughter does well on 27.5, and I’m 172cm on a medium 29er. I think you’d do well on 27.5, and that would be more betterer and more compatibler.

Mountain bike. I’m a newbie and I don’t want to spend much. So, budget is probably around 1000. And Santa cruz is really expensive for me. I’ll look for XS sizes then. Thanks for your reply.

You might fit a small if you have proportionally long limbs. A size S Nukeproof scout 275 or Vitus Sentier starts at 5’2”-5’3” which isn’t far off, and have 380mm seat tubes. They look good value around the £1000 mark.

I’ve recently been looking for a similar sized bike, bang on an extra small for specialized. Usually some healthy discounts around for that size too – Rockhopper no idea if any good, just an example.

I’m 5’1″ tall

So is mrs_oab.

She currently rides an xs Liv Lust.

And xs Liv Invite.

She used to ride a 13.5″ Trek Superlight.
And before that a Cannondale F900SL.
Seen here together.

In our experience, many small or XS frames really are not that small. Many still fit long cranks. And a few mm’s is more important the shorter you are.

There’s a good few Liv or Giant xs full suspension and hardtail for under £1k on eBay at present.

Recommending liv or Giant, Nnnnnoooooo.😀

Isabeau courdurier is your size if not smaller and rides small lapierre mullet, Katy Winton is about the same and has rode small Nukeproof mullet and now small GT mullet, even small 29er when she rode for trek.
Your inside leg and arm length is gonna determine if you need XS or S

Shortyman – are you looking at hardtails or full suspension bikes? If full suspension, there are defo some designs that better accommodate smaller riders. It’s all about standover init.

Liv bikes are great. Son2 had one at your height; Giant Talon 1W. Was a fabulous bike in XS. I sold it to a work colleague who is your height as a first mtb and she absolutely loves it.

I will say that XS frames are hard to source because they don’t make many and they sell very fast. But a well-fitting bike will just feel right.

My daughter has a Whyte 604 which is great, 27.5 and it looks awesome in XS.

Hi, 5ft 0 fella here, and have spent far too long nerding out on bike geo and sizing. Message me if you want a detailed chat, but I’ve found that seat tube (and seat tube insertion) is the biggest limiting factor. Reach is just a preference thing. I can get away with bike with 380mm seat tube (with a decent insertion length), to get a 100mm dropper. Obviously depends on ape index proportions etc, but that’s a rough guide. Ideally you could squeeze a 125mm dropper or even longer with something like a One Up or other low stack post. I went for a S Transition Scout over an XS as I wanted a bit more reach – 425mm. Wouldn’t want less than that personally.

Should be more options these days with shorter seat tubes becoming the norm, it used to be a pain with a lot of brands having long seat tubes.

Wheel size wise, it’s already been mentioned that some short female racers are using mullets. Personally I’ve tried my wife’s full 29er (120mm full suss trail bike), and it’s great on mellow trail centre terrain but a soon as anything pointed properly downhill, my ass was being buzzed a lot. It really limited my movement on the bike, and that’s on a LLS bike where in theory you can stay central. So 27.5 rear wheel is a must for me personally. I’m currently on full 27.5 and happy, but I can see 29 front possibly working but I’m really not sure I could get my bars low enough. I may try it at some point (will “borrow” my wife’s 29er fork and front wheel), but actually I’m not sure I can be bothered!

As Littleton says seat posts can be a problem if there’s bottle bosses on the seat tube. This can stop the seat post going all the way down and may require some cutting to get the saddle at the right height. I suspect that this may be on older frames as newer ones should have provision for a dropper and nothing fouling the internals of seat tube.
A long-winded way of saying droppers may not work for you on older secondhand frames if there’s a bottle boss pair on the seat tube.

Nukeproof size small and Scott size small 29’ers are absolutely fine for my 4’10” 10 yr old

If you’re interested, my missus is selling a small Juliana Joplin (Tallboy). High spec and short seat tube, it’s in the classifieds (shameless plug over).

But for context, my missus is an average proportion 5’2″ and she had a 150mm reverb on it. She’s never had any bike that allowed her to do that. There’s a 100mm Reverb AXS on it now, so I reckon it has a lot of adjustment.

The insertion depth is decent too as the 150mm went in all they way to the collar.

As we’ve also found out, the biggest challenge with small bikes seems to always be the seat tube. I have a similar problem on the other end of the spectrum!

The standard answer is go and sit on a bike before buying, but even at 5ft 6 I know this is near on impossible as no one ever has stock of smaller sized bikes. So feel for you making a decision !

I have short legs and long torso. So to get a bike that I can easily stand over I normally have to go smaller, but then the reach is a bit short

Recommending liv or Giant, Nnnnnoooooo

@noeffsgiven – can I ask why?

I’m guessing it is the Giant not honouring warranty thread.

Based on my kids (sorry) experiences riding and my experiences sourcing parts etc for riders at that sort of height…

Defo 27.5, you’d be daft to go 26 as tyres, wheels etc are increasingly problematic.  Also 27.5 frankly rides better!

XS 27.5 hardtails seemed to be bang on for that sort of height.

Slight stealth ad but I have an XS Ragley Blue Pig frame plus wheels and forks to suit if you’re interested as my kids are now on medium frames.  Drop me a PM if you’re interested.

I’m guessing it is the Giant not honouring warranty thread.

I would place a decent bet on every manufacturer having issues over this, and they are not the only ones who haven’t honoured warranties when it seems obvious they should. My Marin included.

Each to their own – personally (and only having bought second hand) I find Giant well equipped and well made – mrs_oab’s wee full suspension is the straightest FS bike we have owned.

Matt, Glad you’re now up to speed 😁