What size frame is a 22.5" MTB these days?

[Manc33]

My MTB has a sloping top tube, so I got a spirit level and put the corner of it at the center of the head tube, then marked a line on the seatpost where it was level with it.

I measured from the center of the BB to that line and it came to 22.5" (57cm). The effective top tube (measuring again to that same line from the same place on the head tube) is 590mm.

I'm only about 5'10" and yet, despite sounding like a large frame, I could do with a bit more reach than I have and also, quite a lot of the seatpost is poking out of the seat tube, so I am pretty sure it's slightly too small for me if anything, although it's not by much, I am OK on this bike.

Why is my bike a 22.5" (isn't that L or even XL?) when I'm 5'10"?

The actual height of the seat tube is 19" from BB to collar and I am sure this bike was sold as a medium. Another MTB frame I have got is the same size (22.5") and that's also labelled as a medium.

Maybe I'm just harking back to being a kid when an 18" frame fit me.

[rogerzilla]

The sizes are meaningless as each manufacturer has its own system, and Kona changed theirs at least once. You need to look up the geometry ofvthat particular model and size.

[Jamesh]

22" sounds like a reasonable size for a 5'10" chap.

You don't say what sized wheels you use as that will have a bearing on it.

Cheers James

[mattsccm]

Almost pointless exercise, buying bike by size. Exactly the same as clothes and shoes. All the size does is tell you how big it in relationship to other in that makers range. It will change over the years and with styles. Once you know what you need it's easy until they makers change something. Cross referencing different makes is impossible. You don't assume a medium will always fir and bikes are the same.
Sadly

[Manc33]

One takes 26" wheels, the other 27.5" but I have only ever used 26" on both. One feels a better fit than the other. I could easily be 1cm out measuring them. The one I measured to have a 580mm top tube is 590mm on the spec sheet (this is the comfy/perfect fit) and the other one I measured at 590mm on the top tube is 580mm in reality. You need three hands to measure it

The actual seat tube on the one with a 590mm top tube, is 18". The seat tube on the one with the 580mm top tube, is 19". So the one with the shorter seat tube actually has 1cm more reach. Well I say reach but I just mean the effective top tube. I guess that means the top tube slopes a bit more on the 18".

[iandusud]

The most important measurement with regard to frame sizing it the effective top tube length. There is so much available adjustment for the saddle height that the length of the seat tube is almost irrelevant (within reason). There is only limited scope for adjusting the reach by changing stem length, and even this has it's limits as it will affect the steering if taken to excess. So once you have established the reach that suits you base your frame size decision on this. After that I consider the next most important factor to be the height of the front end which will depend upon your flexibility and how aggressively or not you ride. These are often expressed these days as Reach and Stack. Gone are the days when you simply measured the seat tube and the (horizontal) top tube was more or less the same length (what was referred to as a "square frame").

[Zanda]

If you need more reach, you could fit a longer stem. A 22.5" effective top tube on a MTB sounds about right for someone 5' 10"

[Manc33]

If you need more reach, you could fit a longer stem. A 22.5" effective top tube on a MTB sounds about right for someone 5' 10"

That 22.5" is the effective seat tube (if there's an imaginary horizontal line coming from the center of the head tube at the upper bearing).

But if it was the (effective) top tube that's 570mm which is workable but really it's 2cm or 3cm too short for me personally.

I think I must be built like an orangutan (long arms in relation to legs)

[Zanda]

What length stem are you using? And what is the make and model of bike?