thms

Hi,
Currently I'm looking for an old rigid MTB from the 90s. The bike wouldn't be for actual mountain biking but mainly for commuting and city rides.

What I'm wondering about is the proper frame size. If I was searching for a road bike I would just look for frames that are 57 or 58 cm (~22") because I'm 182cm (6 feet) tall with an inseam of 87cm (34").

But in regards of MTBs I'm not sure. The geometry of 1990s MTBs is way more similar to hybrid or even road bikes so can I just go with the size I mentioned above? Or should I follow recent guides that say that one with my size should take a frame from 18.5 to 20" (47-51cm)?

Thanks!

fietsbob

off road when you have to jump off, it has to be far enough, that a foot on the down hill slope

wont hurt too much hitting your crotch the top bar

straddle the bike flat footed one hand on the saddle one hand on the bars/stem lift it straight up ,
how far off the ground are the wheels?


if a street use bike you can use a bigger one than if going off road on singletrack. NB the BB is higher than a road bike. 57-58 would be too big..
my 700c touring bike is a 57..

a sloping top tube measures shorter... 'size' being the seat tube length .. BB axis upward ...

maybe a 54? I have a level top tube Koga Trekking bike..

and an old stumpjumper it's an 18" 46cm (sloping top tube) pre suspension fork geometry..








/....

Colnago Mixte

I'm 5-10", with a 32" inseam, and have found 18" MTB frames on my 90's steel Treks to be slightly too small. Way too much seat post sticking out for my tastes, close to a foot! I think with a 34" inseam, you should be looking at frames that are 19 1/2" and larger. Here is my 18" 1997 Trek Singletrack set up for me to ride:

Bennesota

I'm in a similar situation, a lanky 6'-6'1"" with a 34" inseam, and I like to stretch out my arms and lean forward. I found an 89" GT avalanche 24" that I want to convert to a town cruiser/gravel, but I'm a bike newbie and unsure of the move.

Moisture

Should be fine, but 24" seat tube is about the tallest you'd want to go. Standover could be an issue. I am 6ft3 with a 34.4" inseam and 24" for a mountain bike is about the tallest I would want to go considering that the bottom bracket on mountain bikes is higher up which therefore will impact standover clearance.

A mountain bike is an alright choice for city commuting, but should be fine for gravel depending on which tires and stem you use. I have a 21" GT Zaskar LE from 1998, that is a great bike. I was not aware that GT made anything taller than 23" for the seat tube on the xl's.