MTB Frame sizing??

[Harrison]

Good evening all


I'm pretty new to MTB's, Road bikes and BMX's are my usual bag...

Anyway, how do you size your MTB's?


I'm 6'1 with a 33 inside leg. My road frames are 23", what sort of MTB size would be about right for me? I don't do new stuff so it'll be retro MTB's, and I know sizing is different between old and new...and also between manufacturers.


Cheers
H

 

[Pyro Tim]

I'm not sure of the rule of thumb, but I'm the same height as you, but with longer inside leg, and I ride anything from 17-19"

 

[Harrison]

Cheers

 

[We_are_Stevo]

I'm not sure of the rule of thumb, but I'm the same height as you, but with longer inside leg, and I ride anything from 17-19"

Ditto...

 

[peguinpower]

we are on opposite sides of the spectrum. i am 5'6".

imho, sizing a frame right is more about the saddle to bar distance more than anything else. you can always adjust the saddle height, but reach not so easy on the trail.

my main benchmark in fitting a bike is getting the distance between the tip of the saddle and the center of the handlebar to my ideal length.

i can ride a 21 inch virtual top tube with a 120ish stem. my main modern ride, a trek remedy, has a 17.5 st, 23.25 tt and a 70 mm stem. it fits me very well, no back aches on 4 plus hour rides.

hope that makes sense.

 

[Loki]

At 6'1" I would say 19-20 with TT around 22.5"- 23" unless you want a compact cockpit. Find a frame where you can use the right length stem for which the bike was designed. That means 125-150 for retro stuff and less than 125 for modern IMO. I am 5'10" but have a 33.75" inseam and like to stretch out more than most and ride a 18-20 depending on manufacturer.

 

[02gf74]

rough rule for road is 1/3 your height, then subtract 5 inches for mtb frame

i'm about same dimensions as you and ride 19/20 in mtb frames - 17 in is too small.

top tube length 590 ish mm

 

[drcarlos]

Standover height is key as it's the one thing you can't change.
A 17" frame with a high BB will give a height that will be too high for some. Baz77's MTrax 350 is a good example of this it's a 17" frame C-C but as it has a high BB comes up like a 19" in standover height and is just too big for me as I need an 18" size with most other makers. A seatpost can be changed from layback to inline and vice versa to change saddle to bar reach and so can the stem but you are stuck with 26" wheels and toptube/BB height.
The M-Trax is more the exception than the rule as you'd usually need a 19" like others have said but it's worth actually getting on the thing just to be sure.

Carl.

 

[Harrison]

Excellent info chaps


I have a good idea of what to look for now. I've got a 19" Ozark i'm putting together for a winter bike. But I'd like to build something a bit more special for the summer to go with my BMX & road bike

 

[24pouces]

I have never understood why we only consider the seat tube length and the standover for sizing a frame. It's changing if it's sloping or not, high BB…Quite or more important is the length of the horizontal tube.
For example, the SM800 Beast of the East : sloping frame, high BB, and the smaller size seems to be a small 15". But if you consider the length of the top tube, it's a medium 18"