Sizing for mountain bikes can be hard and while most of us don’t think of it as not so important in the long term it may become annoying as proper sizing and choosing something that fits your body can be more comfortable and it may as well be the reason holding you back.
However, sizing can be a little bit difficult sometimes since most beginners like I was don’t know what they actually like and what kind of trails they will actually be riding on and how the simple geometry term can turn into something that holds you back, That being said I did a lot of research to try to get close to the numbers according to your heights as I could, but nothing is a given let me explain how.
Frame size and Wheel size for heights 4-4.6 :
| height (feet) | frame size(inches) | wheel size(inches) |
|---|---|---|
| 4-4.3 | 13″ | 24″ |
| 4.3-4.6″ | 13″ | 24″ |
I did some research into kids average heights and collected data from many sources including my own personal research to come close to the exact number that I could but as I said nothing is a given it is as close as I could get but these numbers are based on the average heights of kids and I tried to research to get to the exact number rather than give you a formula and be off with that.
The tables cover the average height of a person average frame sizes that the manufacturers make and the average wheel sizes they offer as well.
But this data is not written on the stone there are many other things that play a major role in choosing the right frame size, for example, if your kid is 4 or 4.3 it could be that his legs are a little bit longer, in that case, the frame height that I mentioned maybe a fit but not suitable for him/her.
But as far as general sizing goes I tried my best to at least cover what you should be getting, but as parents, I think you know your kids more than I do and you know their riding styles better than I do, but this is data for reference so people who don’t know anything about geometry can understand it a little bit better and get what are the most important things to look for.
Frame size and Wheel size for heights 4.7-4.11:
| height (feet) | frame size(inches) | wheel size(inches) |
|---|---|---|
| 4.7-4.8″ | 13-14″ | 24″ |
| 4.10-4.11″ | 13-14″ | 24″ |
Frame size and Wheel size for heights 5-5.7 :
| height (feet) | frame size(inches) | wheel size(inches) |
|---|---|---|
| 5-5.4″ | 15- 16″ | 24-26″ |
| 5.5-5.7″ | 15″-16″ | 26″ |
Frame size and Wheel size for heights 5.6-5.8 :
| height (feet) | frame size(inches) | wheel size(inches) |
|---|---|---|
| 5.6-5.8″ | 17-18″ | 27.5-29″ |
| 5.8-5.10 | 18- 19″ | 26-29″ |
Frame size and Wheel size for heights 6-6.5-7 :
| height (feet) | frame size(inches) | wheel size(inches) |
|---|---|---|
| 6-6.5 | 20-22″ | 29″ |
| 7 | 23-24-25″ | 29″ |
Reach and Stand over Heights for ALL ages and heights :
REACH :
Reach is an important factor when it comes to mountain bike sizing and it plays a major role in the comfort and your overall riding style,
Reach is the distance from the handlebar to the seat post and to the middle of the bottom bracket or your gear cassette mid if you don’t know what the bottom bracket is.
In really simple words reach is the distance between your handlebar and you when you sit on your bike it is the area that allows you to maintain the weight on the handlebars while providing you enough room to move around.
the bottom bracket height mentioned is to help you visualize where their feet would be while jumping or bunny hopping or simply skating or performing other tasks.
A good reach provides total control of the rider on his/her bike rather than the opposite and in mountain biking, it becomes more crucial that you have control over your bike rather than the opposite.
if you still don’t understand what I am trying to say then “it’s the feel” if you get the chance to ride on some bikes for some you feel like you could do anything with them but on some bikes everything is alright but you are not quite sure about it so it’s all about “the feel”.
I already did some research to get the most optimal number that could fit you but still, as I say everything is not a given and it’s probably best you try the measurements yourself or try a local shop to do it for you.
Reach varies for men women and kids your height doesn’t count when you are calculating your reach because in most cases you may be taller or shorter but your hands can be shorter or longer irrespective of your height that is why almost all the size calculators for mountain bikes measurement or any bike measurement cannot give you the exact number based on your height only.
| height (feet) | Reach(mm) | stand over height/inseam(inches) |
|---|---|---|
| 4-4.3” | 298-321 | 20-23″ |
| 4.4-4.6″ | 328-343 | 23-25″ |
| height (feet) | Reach(mm) | stand over height/inseam(inches) |
|---|---|---|
| 4.7-4.8″ | 350-358 | 25-27.9 |
| 4.9-4.11″ | 366-367 | 27.9-30.9 |
Stand over height/Inseam :
You may or may not have seen the stand over or inseam on many bikes manufacturers sites, inseam or standover height refers to how comfortably you can stand over your bike see the picture for reference.
still not clear enough, in the most simple terms when you get off of your seat how well can you place your foot on the ground if the top tube isn’t very close to your crown jewels, you may now have a pretty good idea of whats the inseam.
| height (feet) | Reach(mm) | stand over height/inseam(inches) |
|---|---|---|
| 5-5.4″ | 373-403 | 31-32.9″ |
| 5.5-5.7″ | 410-425 | 31-33″ |
Correct inseam and reach are the two main important things in a bike geometry that you should look at when you are deciding to buy a new bike these are the two main factors that decide if the bike would be comfortable for you to ride or not and this is mainly ignored by beginners which lead to the wrong bike which could cost you a lot, these are the things that I look for when I choose a bike for myself as well and I always advise others to do the same.
| height (feet) | Reach(mm) | stand over height/inseam(inches) |
|---|---|---|
| 5.6-5.8″ | 418-433 | 33-33.9″ |
| 5.9-5.11 | 440-445 | 33.9-34.4″ |
| height (feet) | Reach(mm) | stand over height/inseam(inches) |
|---|---|---|
| 6-6.5 | 448-485 | 35.35.9″ |
| 7 | 522 | 36-38″ |
I have already given you a rough number on what the inseam and reach of your bike should be but these numbers are not perfect they are based on the average heights of the people’s inseam or stand-over height may decrease or increase depending on your legs size, not your height.
Your height does not count in your inseam/stand-over height it’s best to keep that in mind, Leg sizes vary between men women, and kids that is a key factor that there is no exact number on what is your inseam height many manufacturers do tend to ask for your leg size when you try measuring yourself through them so its best that you do that.
Also, these numbers are not perfect they can give you the closest number because these numbers are based on the average heights of the people.
How to Calculate the Reach :
For my calculations, I used the following formula.
Your height in cm × 2.45 = convert the answer to mm(millimeter)
this is the formula that I used it worked for me but it may not work for you, Logic behind the formula? not really for me it worked that’s why I considered it worth mentioning but that is all it’s just worth trying not trusting.
I may add that I did go out to get myself measured and bought my bike according to those measurements I will encourage you to do the same.
why not to take measurements yourself :
To begin with, taking measurements is not what you suppose it is measurements for clothes and body are different than measurements taken for bike different aspects go into measurements for bikes.
for example, inseam or standover height now if you take your leg measurements yourself they may fall short of the exact number or vary for some inches that may not look like much but it will turn out to be very uncomfortable when you try riding your bike.
the same goes for the reach you may measure your shoulders and arm length but when you bend down on the bike your posture is different some of your body length counts in there so you may think that those measurements are correct when in fact they are not.
Go to a local shop or if it’s far from you decide a day to go out in the city to get those measurements that’s the best way.
Final Conclusion :
All the online calculators and the static are correct but to the extent that they give a generic or an average number including me, Also not everything depends on the numbers try riding some bikes if some may hit you as comfortable or you can feel yourself those are your numbers, but in most cases, measurements are the way to go most of the people love including my self and they really do work fine.
I hope this article helps you understand geometry a little bit better and what are the most important things to keep in mind or to look for when you are buying a mountain bike.
Stay safe ride Safe
Good luck!